I need help with some LEDs. I bought this Clarion dash-mount EQ on Ebay and
the blue LED's that illuminate all the dials were dead. I went to Radio
Shack and bought five 12 volt LED's and installed them into the unit. They
are NOT wired to any of the EQ wiring. They have their own positive and
negative leads coming out of the EQ (obviously, this is something I did, not
Clarion). Now this worked GREAT on my 13.5 volt bench power supply. But in
my car hooked up to my ignition voltage, it SUCKS. It is CONSTANTLY
changing brightness with engine voltage going from nearly off when the car
is idling to VERY BRIGHT when the car is at a high RPM. I KNOW there must
be a way to even-out this voltage, so it maintains a CONSTANT 13 volts (it
uses hardly any amperage, of course), but I don't know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want to as
that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Thanks,

MOSFET

Also, I should add that I wired them in series. Should I have wired them in
parallel? Is that my problem?

Thanks,

MOSFET

"MOSFET" wrote in message
...
I need help with some LEDs. I bought this Clarion dash-mount EQ on Ebay
and the blue LED's that illuminate all the dials were dead. I went to
Radio Shack and bought five 12 volt LED's and installed them into the unit.
They are NOT wired to any of the EQ wiring. They have their own positive
and negative leads coming out of the EQ (obviously, this is something I
did, not Clarion). Now this worked GREAT on my 13.5 volt bench power
supply. But in my car hooked up to my ignition voltage, it SUCKS. It is
CONSTANTLY changing brightness with engine voltage going from nearly off
when the car is idling to VERY BRIGHT when the car is at a high RPM. I
KNOW there must be a way to even-out this voltage, so it maintains a
CONSTANT 13 volts (it uses hardly any amperage, of course), but I don't
know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want to
as that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Thanks,

MOSFET

Geez, I'm losing it. They were not 12 volt LED's. They were 3 volt.
That's why I wired 5 in series. I thought that would be about right (I
know, that's 15 volts, that's part of my problem I guess). Anyway, my
question still applies, I need a CONSTANT 13-15 volts.

MOSFET
"MOSFET" wrote in message
...
I need help with some LEDs. I bought this Clarion dash-mount EQ on Ebay
and the blue LED's that illuminate all the dials were dead. I went to
Radio Shack and bought five 12 volt LED's and installed them into the unit.
They are NOT wired to any of the EQ wiring. They have their own positive
and negative leads coming out of the EQ (obviously, this is something I
did, not Clarion). Now this worked GREAT on my 13.5 volt bench power
supply. But in my car hooked up to my ignition voltage, it SUCKS. It is
CONSTANTLY changing brightness with engine voltage going from nearly off
when the car is idling to VERY BRIGHT when the car is at a high RPM. I
KNOW there must be a way to even-out this voltage, so it maintains a
CONSTANT 13 volts (it uses hardly any amperage, of course), but I don't
know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want to
as that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Thanks,

MOSFET

Hook them up in parallel with a 620ohm or 680ohm 1 watt resistor.



In article , "MOSFET"
wrote:
Geez, I'm losing it. They were not 12 volt LED's. They were 3 volt.
That's why I wired 5 in series. I thought that would be about right (I
know, that's 15 volts, that's part of my problem I guess). Anyway, my
question still applies, I need a CONSTANT 13-15 volts.

MOSFET
"MOSFET" wrote in message
...
I need help with some LEDs. I bought this Clarion dash-mount EQ on Ebay
and the blue LED's that illuminate all the dials were dead. I went to
Radio Shack and bought five 12 volt LED's and installed them into the unit.
They are NOT wired to any of the EQ wiring. They have their own positive
and negative leads coming out of the EQ (obviously, this is something I
did, not Clarion). Now this worked GREAT on my 13.5 volt bench power
supply. But in my car hooked up to my ignition voltage, it SUCKS. It is
CONSTANTLY changing brightness with engine voltage going from nearly off
when the car is idling to VERY BRIGHT when the car is at a high RPM. I
KNOW there must be a way to even-out this voltage, so it maintains a
CONSTANT 13 volts (it uses hardly any amperage, of course), but I don't
know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want to
as that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Thanks,

MOSFET

There is no such thing as a 12volt LED or a 3volt LED or an X, Y or Z
volt LED.

I am DEFINITELY no LED expert. But the package the Radio Shack LED came in
said 3 volt LED on the front, so that's what I'm calling it.

MOSFET

"Captain Howdy" wrote in message
news

Hook them up in parallel with a 620ohm or 680ohm 1 watt resistor.

OK, I'll try this. I'm not going to fry my bench power source am I? I
mean, you were the one who said to try 1000 watts per tweeter.

MOSFET

"Captain Howdy" wrote in message
news

Hook them up in parallel with a 620ohm or 680ohm 1 watt resistor.

Cpt., should the resister be hooked up on the positive or negative lead? Or
does it matter?

And I've been meaning to ask, is the handle Captain Howdy from that movie
where the kid has an imaginary (murdering) friend (the name escapes me)?

MOSFET

Oh, wait a sec., you mean that the resister should be in parallel with the
other LED's, right? I'm pretty sure that's what you meant (it's early, I
haven't had my coffee yet).

MOSFET

"MOSFET" wrote in message
...

"Captain Howdy" wrote in message
news

Hook them up in parallel with a 620ohm or 680ohm 1 watt resistor.

Cpt., should the resister be hooked up on the positive or negative lead?
Or does it matter?

And I've been meaning to ask, is the handle Captain Howdy from that movie
where the kid has an imaginary (murdering) friend (the name escapes me)?

MOSFET

"MOSFET" wrote in message
m...
There is no such thing as a 12volt LED or a 3volt LED or an X, Y or Z
volt LED.

I am DEFINITELY no LED expert. But the package the Radio Shack LED came
in said 3 volt LED on the front, so that's what I'm calling it.


Go back to Radio shack and ask for a voltage regulator. It's a small device
that will maintain voltage. You'll probably need that resistor as well. As
the guys at Radio Shack (find the nerd) about it -- this is basic and at
least one of them should know it. Catalog price is $1.59 and it will
provide a constant five volts at up to 1 Amp in current. There are other
sizes/voltages available, but I think this one will do you fine. Here's the
URL for the Radio Shack Catalog:

http://www.radioshack.com/product/in...entPage=family

PD

That's PERFECT! THANK YOU SO MUCH! It has three leads, how do I hook it up?

MOSFET

"Phonedude" wrote in message
news:lTDOf.3755$CT.2148@trnddc04...

"MOSFET" wrote in message
m...
There is no such thing as a 12volt LED or a 3volt LED or an X, Y or Z
volt LED.

I am DEFINITELY no LED expert. But the package the Radio Shack LED came
in said 3 volt LED on the front, so that's what I'm calling it.


Go back to Radio shack and ask for a voltage regulator. It's a small
device that will maintain voltage. You'll probably need that resistor as
well. As the guys at Radio Shack (find the nerd) about it -- this is
basic and at least one of them should know it. Catalog price is $1.59 and
it will provide a constant five volts at up to 1 Amp in current. There
are other sizes/voltages available, but I think this one will do you fine.
Here's the URL for the Radio Shack Catalog:

http://www.radioshack.com/product/in...entPage=family

PD

Also, will I really still need the resistor? If I wire all five LED's in
parallel is five volts too much? I would think a 3 volt LED could handle 5
volts.
MOSFET


"Phonedude" wrote in message
news:lTDOf.3755$CT.2148@trnddc04...

"MOSFET" wrote in message
m...
There is no such thing as a 12volt LED or a 3volt LED or an X, Y or Z
volt LED.

I am DEFINITELY no LED expert. But the package the Radio Shack LED came
in said 3 volt LED on the front, so that's what I'm calling it.


Go back to Radio shack and ask for a voltage regulator. It's a small
device that will maintain voltage. You'll probably need that resistor as
well. As the guys at Radio Shack (find the nerd) about it -- this is
basic and at least one of them should know it. Catalog price is $1.59 and
it will provide a constant five volts at up to 1 Amp in current. There
are other sizes/voltages available, but I think this one will do you fine.
Here's the URL for the Radio Shack Catalog:

http://www.radioshack.com/product/in...entPage=family

PD

Great! Just what I wanted to hear. And how can I check that the subs are
still good without connecting another amp to it????? Thanks again.

"MOSFET" wrote in message
...
I need help with some LEDs. I bought this Clarion dash-mount EQ on Ebay
and the blue LED's that illuminate all the dials were dead. I went to
Radio Shack and bought five 12 volt LED's and installed them into the unit.
They are NOT wired to any of the EQ wiring. They have their own positive
and negative leads coming out of the EQ (obviously, this is something I
did, not Clarion). Now this worked GREAT on my 13.5 volt bench power
supply. But in my car hooked up to my ignition voltage, it SUCKS. It is
CONSTANTLY changing brightness with engine voltage going from nearly off
when the car is idling to VERY BRIGHT when the car is at a high RPM. I
KNOW there must be a way to even-out this voltage, so it maintains a
CONSTANT 13 volts (it uses hardly any amperage, of course), but I don't
know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want to
as that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Thanks,

MOSFET

As for a LED handling 5V, that is all relevant to the diode themselves. At
certain voltages a diode will reach what is called the avalanche point where
the resistance in the diode becomes very very low and current rushes through
and the diode will breakdown thermally.

--
- AUSTIN BECKER
"MOSFET" wrote in message
m...
Also, will I really still need the resistor? If I wire all five LED's in
parallel is five volts too much? I would think a 3 volt LED could handle
5
volts.
MOSFET


"Phonedude" wrote in message
news:lTDOf.3755$CT.2148@trnddc04...

"MOSFET" wrote in message
m...
There is no such thing as a 12volt LED or a 3volt LED or an X, Y or Z
volt LED.

I am DEFINITELY no LED expert. But the package the Radio Shack LED
came
in said 3 volt LED on the front, so that's what I'm calling it.


Go back to Radio shack and ask for a voltage regulator. It's a small
device that will maintain voltage. You'll probably need that resistor
as
well. As the guys at Radio Shack (find the nerd) about it -- this is
basic and at least one of them should know it. Catalog price is $1.59
and
it will provide a constant five volts at up to 1 Amp in current. There
are other sizes/voltages available, but I think this one will do you
fine.
Here's the URL for the Radio Shack Catalog:


http://www.radioshack.com/product/in...entPage=family

PD

It wont burn out your bench power source, unless its rated at less then an
amp. That rating is good for a 14- 15 volt source. What's wrong with a 1000
watts a tweeter anyways.lol


In article , "MOSFET"
wrote:

"Captain Howdy" wrote in message
news

Hook them up in parallel with a 620ohm or 680ohm 1 watt resistor.

OK, I'll try this. I'm not going to fry my bench power source am I? I
mean, you were the one who said to try 1000 watts per tweeter.

MOSFET

shouldnt matter, but I always use the positive lead.



In article , "MOSFET"
wrote:

"Captain Howdy" wrote in message
news

Hook them up in parallel with a 620ohm or 680ohm 1 watt resistor.

Cpt., should the resister be hooked up on the positive or negative lead? Or
does it matter?

And I've been meaning to ask, is the handle Captain Howdy from that movie
where the kid has an imaginary (murdering) friend (the name escapes me)?

MOSFET

yup, the resistor goes between the positive lead of the power supply and the
positive led string.


led's+ resistor power supply+

In article , "MOSFET"
wrote:
Oh, wait a sec., you mean that the resister should be in parallel with the
other LED's, right? I'm pretty sure that's what you meant (it's early, I
haven't had my coffee yet).

MOSFET

"MOSFET" wrote in message
...

"Captain Howdy" wrote in message
news

Hook them up in parallel with a 620ohm or 680ohm 1 watt resistor.

Cpt., should the resister be hooked up on the positive or negative lead?
Or does it matter?

And I've been meaning to ask, is the handle Captain Howdy from that movie
where the kid has an imaginary (murdering) friend (the name escapes me)?

MOSFET

Your alternator already has a 14.5 volt regulator, so adding a 5 volt
regulator plus as resistor has the advantage of what, other then using a lower
value of resistor? What is your point I'm all ears ? lol


In article lTDOf.3755$CT.2148@trnddc04, "Phonedude"
wrote:

"MOSFET" wrote in message
om...
There is no such thing as a 12volt LED or a 3volt LED or an X, Y or Z
volt LED.

I am DEFINITELY no LED expert. But the package the Radio Shack LED came
in said 3 volt LED on the front, so that's what I'm calling it.


Go back to Radio shack and ask for a voltage regulator. It's a small device
that will maintain voltage. You'll probably need that resistor as well. As
the guys at Radio Shack (find the nerd) about it -- this is basic and at
least one of them should know it. Catalog price is $1.59 and it will
provide a constant five volts at up to 1 Amp in current. There are other
sizes/voltages available, but I think this one will do you fine. Here's the
URL for the Radio Shack Catalog:

http://www.radioshack.com/product/in...2032058.203223
0.2032279&allCount=27&fbn=Type%2FIC-Analog&f=PAD%2FProduct+Type%2FIC-Analog&fbc
=1&parentPage=family

PD

most 3mm leds have a forward voltage of : 3.2-3.6v


In article QNFOf.595862$084.412017@attbi_s22, "Austin Becker"
wrote:
As for a LED handling 5V, that is all relevant to the diode themselves. At
certain voltages a diode will reach what is called the avalanche point where
the resistance in the diode becomes very very low and current rushes through
and the diode will breakdown thermally.

Use an ohm meter and see what reading you get on each coil. A good 4ohm coil
should have a reading of no less then 3.5 ohms


In article CGFOf.23794$kp3.7633@fed1read03, "ElGalanazo"
wrote:
Great! Just what I wanted to hear. And how can I check that the subs are
still good without connecting another amp to it????? Thanks again.

"MOSFET" wrote in message
...
I need help with some LEDs. I bought this Clarion dash-mount EQ on Ebay
and the blue LED's that illuminate all the dials were dead. I went to
Radio Shack and bought five 12 volt LED's and installed them into the unit.
They are NOT wired to any of the EQ wiring. They have their own positive
and negative leads coming out of the EQ (obviously, this is something I
did, not Clarion). Now this worked GREAT on my 13.5 volt bench power
supply. But in my car hooked up to my ignition voltage, it SUCKS. It is
CONSTANTLY changing brightness with engine voltage going from nearly off
when the car is idling to VERY BRIGHT when the car is at a high RPM. I
KNOW there must be a way to even-out this voltage, so it maintains a
CONSTANT 13 volts (it uses hardly any amperage, of course), but I don't
know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want to
as that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Thanks,

MOSFET

"MOSFET" wrote in message
...
That's PERFECT! THANK YOU SO MUCH! It has three leads, how do I hook it
up?


It should come with a diagram -- one lead in your 12v input, the center is
common, and the other lead is your 5v output. Don't take my word though,
please look at the diagram that comes with it. Also make sure you put a
resistor (1000 ohm recommend) across your output.

PD




MOSFET

"Phonedude" wrote in message
news:lTDOf.3755$CT.2148@trnddc04...

"MOSFET" wrote in message
m...
There is no such thing as a 12volt LED or a 3volt LED or an X, Y or Z
volt LED.

I am DEFINITELY no LED expert. But the package the Radio Shack LED came
in said 3 volt LED on the front, so that's what I'm calling it.


Go back to Radio shack and ask for a voltage regulator. It's a small
device that will maintain voltage. You'll probably need that resistor as
well. As the guys at Radio Shack (find the nerd) about it -- this is
basic and at least one of them should know it. Catalog price is $1.59
and it will provide a constant five volts at up to 1 Amp in current.
There are other sizes/voltages available, but I think this one will do
you fine. Here's the URL for the Radio Shack Catalog:

http://www.radioshack.com/product/in...entPage=family

PD

"Captain Howdy" wrote in message
...
Your alternator already has a 14.5 volt regulator, so adding a 5 volt
regulator plus as resistor has the advantage of what, other then using a
lower
value of resistor? What is your point I'm all ears ? lol

From your attitude I doubt you'll care what I say, but a solid state voltage
regulater is a very common device used to deliver a fixed voltage. It will
provide a solid 5 volts to the led array regardless of how much the
alternator voltage goes up and down as the rpm change and the load changes.
As long as the input is greater than 5 volts, of course. The orignal poster
complained of the brightness changing as the voltage from his alternator
changed. This will solve the problem efficiently and solidly. A simple
resistor will not.

PD




In article lTDOf.3755$CT.2148@trnddc04, "Phonedude"

wrote:

"MOSFET" wrote in message
news:zOKdnde3rIspnJbZnZ2dnUVZ_tKdnZ2d@wavecable. com...
There is no such thing as a 12volt LED or a 3volt LED or an X, Y or Z
volt LED.

I am DEFINITELY no LED expert. But the package the Radio Shack LED came
in said 3 volt LED on the front, so that's what I'm calling it.


Go back to Radio shack and ask for a voltage regulator. It's a small
device
that will maintain voltage. You'll probably need that resistor as well.
As
the guys at Radio Shack (find the nerd) about it -- this is basic and at
least one of them should know it. Catalog price is $1.59 and it will
provide a constant five volts at up to 1 Amp in current. There are other
sizes/voltages available, but I think this one will do you fine. Here's
the
URL for the Radio Shack Catalog:

http://www.radioshack.com/product/in...2032058.203223
0.2032279&allCount=27&fbn=Type%2FIC-Analog&f=PAD%2FProduct+Type%2FIC-Analog&fbc
=1&parentPage=family

PD

"Bill Payer" wrote in message
...
On Sun, 5 Mar 2006 08:35:45 -0800, "MOSFET"
wrote:

That's PERFECT! THANK YOU SO MUCH! It has three leads, how do I hook it
up?

This is a 7805 device , 78 donates a positive voltage device, as
opposed to the 79 series negative voltage device; the 05 shows it to
be a 5volt device , others types are 09, 12, etc.
You could use the LM713T which will let you set the output voltage
from 1.2 to 37 volts.

One lead is the Input (+15volts) one lead is the Output (+5volts) and
the 3rd lead is the common ground. Connect your current limiting
resistor to either the +ve or ground line, but the +ve is usually used
by convention.
Look here for a circuit showing how to wire up a 7805 ( the capacitors
are not needed to make it work and can be omitted if space is a
problem)
http://www.tkk.fi/Misc/Electronics/circuits/psu_5v.html

BP.

Excellent reference -- perhaps Captain Howdy should read it.

PD



Here's the URL for the Radio Shack Catalog:
http://www.radioshack.com/product/in...entPage=family

Sure his leds are dimming wired in series, Wired in parallel This should not
be an issue. You dont see led car bulbs dimming or tail lights on trucks and
buses dimming. The only problem with an 7805 is that it could be a fire
hazzard if not heatsinked. Taking the long way from point A to point B will
still get you there.

From your attitude I doubt you'll care what I say, but a solid state voltage
regulater is a very common device used to deliver a fixed voltage. It will
provide a solid 5 volts to the led array regardless of how much the
alternator voltage goes up and down as the rpm change and the load changes.
As long as the input is greater than 5 volts, of course. The orignal poster
complained of the brightness changing as the voltage from his alternator
changed. This will solve the problem efficiently and solidly. A simple
resistor will not.

MOSFET wrote:
I need help with some LEDs. I bought this Clarion dash-mount EQ on Ebay and
the blue LED's that illuminate all the dials were dead. I went to Radio
Shack and bought five 12 volt LED's and installed them into the unit. They
are NOT wired to any of the EQ wiring. They have their own positive and
negative leads coming out of the EQ (obviously, this is something I did, not
Clarion). Now this worked GREAT on my 13.5 volt bench power supply. But in
my car hooked up to my ignition voltage, it SUCKS. It is CONSTANTLY
changing brightness with engine voltage going from nearly off when the car
is idling to VERY BRIGHT when the car is at a high RPM. I KNOW there must
be a way to even-out this voltage, so it maintains a CONSTANT 13 volts (it
uses hardly any amperage, of course), but I don't know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want to as
that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Alright, there's a lot of speculation and half-assed information
floating around here; let's try to clear a few things up. Note: this is
based on the assumption that these are just straight-up LEDs with no
built-in resistors or other circuitry (what is the RS part number?)

First, a voltage regulator is overkill. The problem you're having with
fluctuating brightness is because wiring them in series is dropping the
voltage across individual LEDs to below each one's forward voltage.

Any diode will not begin conducting current until the voltage reaches a
certain level: for germanium diodes, it's typically about .7V; for
silicon diodes it's 1.4V; and for LEDs it's usually around 2-3V. Once
you reach that voltage level, it will begin conducting the full voltage
through with next to no resistance to the current. That means if you
just hook up an LED across your car battery, it will appear as pretty
much a dead short, and will glow very very brightly... for a few
milliseconds.

Now what you did in your orignal setup was to split the car's voltage
evenly across the five LEDs - if each one drops exacly 3V, then to run
them all, you need a solid 15V; any less, and the voltage per diode
drops. As it drops below the avalanche point, they'll stop conducting;
if ONE stops conducting, they ALL shut down.

So what you want to do is wire the LEDs in parallel, so each one gets
the full available voltage. Again, this will normally allow all
available current to flow through each one until they melt down, so you
need to limit the current with a resistor (or resistors). Most LEDs
require around 12-20mA, so using Ohm's Law, we can calculate, assuming
an average 14V and a median 16mA (check the package specs):
14 volts / 0.016 amps = 875 ohms.

So an 875-ohm resistor in series with EACH LED will give you a good
mid-level brightness; now the closest standard resisitance to that is
820 ohms, which will be a little brigher, but not noticeably so; assume
a 10% tolerance and it's well within range. Figure 14V*0.016A=.224W, so
a quarter-watt unit will be fine (1/4W, 10% resistors are about the most
commonly available, so it makes for easy shopping).

You could simplify things a bit by using one resistor to feed all five
in parallel. Since this would require 5*16mA, or 80mA, you need
14V/0.08A=175 ohms total (or just do 875/5). A 150 or 180 ohm resistor
will do, but keep in mind, the power draw will increase accordingly, to
about 1.25W, so you'll want a resistor that will handle at least 1W.

So your wiring would look like this:

820ohm LED
+----/\/\/\/--||----+
+----/\/\/\/--||----+
+12V--+----/\/\/\/--||----+--ground
+----/\/\/\/--||----+
+----/\/\/\/--||----+

Or

+--||----+
150ohm +--||----+
+12V---/\/\/\/--+--||----+--ground
+--||----+
+--||----+

(Use a fixed-width font or the diagrams will look nasty)

Brightness may vary a little with voltage variations, but shouldn't be
any more than the dash lights normally vary. If it's too much, you can
go to the voltage regulator (use the same setup, but put a 12V regulator
at the input of the whole thing, so you don't have to muck around with
changing all the resistor values), but I don't think that will be necessary.

Actually, I'd be very surprised if all five original LEDs in the EQ were
actually fried; I'd expect it's more liklely just a broken connection
feeding them, or at worst, whatever was feeding them (probably a
resistor, maybe a resistor/transistor setup for a constant-current
supply) was toasted. I'd give the EQ a good going-over for a broken
circuit trace or loose wire before going to all the effort of rigging up
a completely separate display.


---
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Virus Database (VPS): 0609-3, 03/03/2006
Tested on: 3/5/2006 1:22:02 PM
avast! - copyright (c) 1988-2005 ALWIL Software.
http://www.avast.com

Well said!

--
- AUSTIN BECKER
"Matt Ion" wrote in message
news:cEIOf.107123$sa3.93267@pd7tw1no...
MOSFET wrote:
I need help with some LEDs. I bought this Clarion dash-mount EQ on Ebay
and
the blue LED's that illuminate all the dials were dead. I went to Radio
Shack and bought five 12 volt LED's and installed them into the unit.
They
are NOT wired to any of the EQ wiring. They have their own positive and
negative leads coming out of the EQ (obviously, this is something I did,
not
Clarion). Now this worked GREAT on my 13.5 volt bench power supply.
But in
my car hooked up to my ignition voltage, it SUCKS. It is CONSTANTLY
changing brightness with engine voltage going from nearly off when the
car
is idling to VERY BRIGHT when the car is at a high RPM. I KNOW there
must
be a way to even-out this voltage, so it maintains a CONSTANT 13 volts
(it
uses hardly any amperage, of course), but I don't know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want to
as
that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Alright, there's a lot of speculation and half-assed information
floating around here; let's try to clear a few things up. Note: this is
based on the assumption that these are just straight-up LEDs with no
built-in resistors or other circuitry (what is the RS part number?)

First, a voltage regulator is overkill. The problem you're having with
fluctuating brightness is because wiring them in series is dropping the
voltage across individual LEDs to below each one's forward voltage.

Any diode will not begin conducting current until the voltage reaches a
certain level: for germanium diodes, it's typically about .7V; for
silicon diodes it's 1.4V; and for LEDs it's usually around 2-3V. Once
you reach that voltage level, it will begin conducting the full voltage
through with next to no resistance to the current. That means if you
just hook up an LED across your car battery, it will appear as pretty
much a dead short, and will glow very very brightly... for a few
milliseconds.

Now what you did in your orignal setup was to split the car's voltage
evenly across the five LEDs - if each one drops exacly 3V, then to run
them all, you need a solid 15V; any less, and the voltage per diode
drops. As it drops below the avalanche point, they'll stop conducting;
if ONE stops conducting, they ALL shut down.

So what you want to do is wire the LEDs in parallel, so each one gets
the full available voltage. Again, this will normally allow all
available current to flow through each one until they melt down, so you
need to limit the current with a resistor (or resistors). Most LEDs
require around 12-20mA, so using Ohm's Law, we can calculate, assuming
an average 14V and a median 16mA (check the package specs):
14 volts / 0.016 amps = 875 ohms.

So an 875-ohm resistor in series with EACH LED will give you a good
mid-level brightness; now the closest standard resisitance to that is
820 ohms, which will be a little brigher, but not noticeably so; assume
a 10% tolerance and it's well within range. Figure 14V*0.016A=.224W, so
a quarter-watt unit will be fine (1/4W, 10% resistors are about the most
commonly available, so it makes for easy shopping).

You could simplify things a bit by using one resistor to feed all five
in parallel. Since this would require 5*16mA, or 80mA, you need
14V/0.08A=175 ohms total (or just do 875/5). A 150 or 180 ohm resistor
will do, but keep in mind, the power draw will increase accordingly, to
about 1.25W, so you'll want a resistor that will handle at least 1W.

So your wiring would look like this:

820ohm LED
+----/\/\/\/--||----+
+----/\/\/\/--||----+
+12V--+----/\/\/\/--||----+--ground
+----/\/\/\/--||----+
+----/\/\/\/--||----+

Or

+--||----+
150ohm +--||----+
+12V---/\/\/\/--+--||----+--ground
+--||----+
+--||----+

(Use a fixed-width font or the diagrams will look nasty)

Brightness may vary a little with voltage variations, but shouldn't be
any more than the dash lights normally vary. If it's too much, you can
go to the voltage regulator (use the same setup, but put a 12V regulator
at the input of the whole thing, so you don't have to muck around with
changing all the resistor values), but I don't think that will be
necessary.

Actually, I'd be very surprised if all five original LEDs in the EQ were
actually fried; I'd expect it's more liklely just a broken connection
feeding them, or at worst, whatever was feeding them (probably a
resistor, maybe a resistor/transistor setup for a constant-current
supply) was toasted. I'd give the EQ a good going-over for a broken
circuit trace or loose wire before going to all the effort of rigging up
a completely separate display.


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I'm so confused. Stop fighting!

MOSFET

"Captain Howdy" wrote in message
...
Sure his leds are dimming wired in series, Wired in parallel This should
not
be an issue. You dont see led car bulbs dimming or tail lights on trucks
and
buses dimming. The only problem with an 7805 is that it could be a fire
hazzard if not heatsinked. Taking the long way from point A to point B
will
still get you there.

From your attitude I doubt you'll care what I say, but a solid state
voltage
regulater is a very common device used to deliver a fixed voltage. It
will
provide a solid 5 volts to the led array regardless of how much the
alternator voltage goes up and down as the rpm change and the load
changes.
As long as the input is greater than 5 volts, of course. The orignal
poster
complained of the brightness changing as the voltage from his alternator
changed. This will solve the problem efficiently and solidly. A simple
resistor will not.

THAT WAS GREAT. Thank you for taking the time to explain each option and
how everything worked. I think I will try the single resistor option first.
Just so I'm REALLY sure on this (because frankly I didn't understand the
diagrams, sorry), I will hook all five LED's in parallel and then parallel
in the 180 ohm resistor (hooked up like it was another LED). Is that right?

THANK YOU SO MUCH.

MOSFET


"Matt Ion" wrote in message
news:cEIOf.107123$sa3.93267@pd7tw1no...
MOSFET wrote:
I need help with some LEDs. I bought this Clarion dash-mount EQ on Ebay
and the blue LED's that illuminate all the dials were dead. I went to
Radio Shack and bought five 12 volt LED's and installed them into the
unit. They are NOT wired to any of the EQ wiring. They have their own
positive and negative leads coming out of the EQ (obviously, this is
something I did, not Clarion). Now this worked GREAT on my 13.5 volt
bench power supply. But in my car hooked up to my ignition voltage, it
SUCKS. It is CONSTANTLY changing brightness with engine voltage going
from nearly off when the car is idling to VERY BRIGHT when the car is at
a high RPM. I KNOW there must be a way to even-out this voltage, so it
maintains a CONSTANT 13 volts (it uses hardly any amperage, of course),
but I don't know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want to
as that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Alright, there's a lot of speculation and half-assed information floating
around here; let's try to clear a few things up. Note: this is based on
the assumption that these are just straight-up LEDs with no built-in
resistors or other circuitry (what is the RS part number?)

First, a voltage regulator is overkill. The problem you're having with
fluctuating brightness is because wiring them in series is dropping the
voltage across individual LEDs to below each one's forward voltage.

Any diode will not begin conducting current until the voltage reaches a
certain level: for germanium diodes, it's typically about .7V; for silicon
diodes it's 1.4V; and for LEDs it's usually around 2-3V. Once you reach
that voltage level, it will begin conducting the full voltage through with
next to no resistance to the current. That means if you just hook up an
LED across your car battery, it will appear as pretty much a dead short,
and will glow very very brightly... for a few milliseconds.

Now what you did in your orignal setup was to split the car's voltage
evenly across the five LEDs - if each one drops exacly 3V, then to run
them all, you need a solid 15V; any less, and the voltage per diode drops.
As it drops below the avalanche point, they'll stop conducting; if ONE
stops conducting, they ALL shut down.

So what you want to do is wire the LEDs in parallel, so each one gets the
full available voltage. Again, this will normally allow all available
current to flow through each one until they melt down, so you need to
limit the current with a resistor (or resistors). Most LEDs require
around 12-20mA, so using Ohm's Law, we can calculate, assuming an average
14V and a median 16mA (check the package specs):
14 volts / 0.016 amps = 875 ohms.

So an 875-ohm resistor in series with EACH LED will give you a good
mid-level brightness; now the closest standard resisitance to that is 820
ohms, which will be a little brigher, but not noticeably so; assume a 10%
tolerance and it's well within range. Figure 14V*0.016A=.224W, so a
quarter-watt unit will be fine (1/4W, 10% resistors are about the most
commonly available, so it makes for easy shopping).

You could simplify things a bit by using one resistor to feed all five in
parallel. Since this would require 5*16mA, or 80mA, you need
14V/0.08A=175 ohms total (or just do 875/5). A 150 or 180 ohm resistor
will do, but keep in mind, the power draw will increase accordingly, to
about 1.25W, so you'll want a resistor that will handle at least 1W.

So your wiring would look like this:

820ohm LED
+----/\/\/\/--||----+
+----/\/\/\/--||----+
+12V--+----/\/\/\/--||----+--ground
+----/\/\/\/--||----+
+----/\/\/\/--||----+

Or

+--||----+
150ohm +--||----+
+12V---/\/\/\/--+--||----+--ground
+--||----+
+--||----+

(Use a fixed-width font or the diagrams will look nasty)

Brightness may vary a little with voltage variations, but shouldn't be any
more than the dash lights normally vary. If it's too much, you can go to
the voltage regulator (use the same setup, but put a 12V regulator at the
input of the whole thing, so you don't have to muck around with changing
all the resistor values), but I don't think that will be necessary.

Actually, I'd be very surprised if all five original LEDs in the EQ were
actually fried; I'd expect it's more liklely just a broken connection
feeding them, or at worst, whatever was feeding them (probably a resistor,
maybe a resistor/transistor setup for a constant-current supply) was
toasted. I'd give the EQ a good going-over for a broken circuit trace or
loose wire before going to all the effort of rigging up a completely
separate display.


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Yes, well said. You guys are soooooo smart. I LOVE RAC!!!!

MOSFET



"Austin Becker" wrote in message
news:U4JOf.596553$084.292747@attbi_s22...
Well said!

--
- AUSTIN BECKER
"Matt Ion" wrote in message
news:cEIOf.107123$sa3.93267@pd7tw1no...
MOSFET wrote:
I need help with some LEDs. I bought this Clarion dash-mount EQ on
Ebay
and
the blue LED's that illuminate all the dials were dead. I went to
Radio
Shack and bought five 12 volt LED's and installed them into the unit.
They
are NOT wired to any of the EQ wiring. They have their own positive
and
negative leads coming out of the EQ (obviously, this is something I
did,
not
Clarion). Now this worked GREAT on my 13.5 volt bench power supply.
But in
my car hooked up to my ignition voltage, it SUCKS. It is CONSTANTLY
changing brightness with engine voltage going from nearly off when the
car
is idling to VERY BRIGHT when the car is at a high RPM. I KNOW there
must
be a way to even-out this voltage, so it maintains a CONSTANT 13 volts
(it
uses hardly any amperage, of course), but I don't know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want
to
as
that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Alright, there's a lot of speculation and half-assed information
floating around here; let's try to clear a few things up. Note: this is
based on the assumption that these are just straight-up LEDs with no
built-in resistors or other circuitry (what is the RS part number?)

First, a voltage regulator is overkill. The problem you're having with
fluctuating brightness is because wiring them in series is dropping the
voltage across individual LEDs to below each one's forward voltage.

Any diode will not begin conducting current until the voltage reaches a
certain level: for germanium diodes, it's typically about .7V; for
silicon diodes it's 1.4V; and for LEDs it's usually around 2-3V. Once
you reach that voltage level, it will begin conducting the full voltage
through with next to no resistance to the current. That means if you
just hook up an LED across your car battery, it will appear as pretty
much a dead short, and will glow very very brightly... for a few
milliseconds.

Now what you did in your orignal setup was to split the car's voltage
evenly across the five LEDs - if each one drops exacly 3V, then to run
them all, you need a solid 15V; any less, and the voltage per diode
drops. As it drops below the avalanche point, they'll stop conducting;
if ONE stops conducting, they ALL shut down.

So what you want to do is wire the LEDs in parallel, so each one gets
the full available voltage. Again, this will normally allow all
available current to flow through each one until they melt down, so you
need to limit the current with a resistor (or resistors). Most LEDs
require around 12-20mA, so using Ohm's Law, we can calculate, assuming
an average 14V and a median 16mA (check the package specs):
14 volts / 0.016 amps = 875 ohms.

So an 875-ohm resistor in series with EACH LED will give you a good
mid-level brightness; now the closest standard resisitance to that is
820 ohms, which will be a little brigher, but not noticeably so; assume
a 10% tolerance and it's well within range. Figure 14V*0.016A=.224W, so
a quarter-watt unit will be fine (1/4W, 10% resistors are about the most
commonly available, so it makes for easy shopping).

You could simplify things a bit by using one resistor to feed all five
in parallel. Since this would require 5*16mA, or 80mA, you need
14V/0.08A=175 ohms total (or just do 875/5). A 150 or 180 ohm resistor
will do, but keep in mind, the power draw will increase accordingly, to
about 1.25W, so you'll want a resistor that will handle at least 1W.

So your wiring would look like this:

820ohm LED
+----/\/\/\/--||----+
+----/\/\/\/--||----+
+12V--+----/\/\/\/--||----+--ground
+----/\/\/\/--||----+
+----/\/\/\/--||----+

Or

+--||----+
150ohm +--||----+
+12V---/\/\/\/--+--||----+--ground
+--||----+
+--||----+

(Use a fixed-width font or the diagrams will look nasty)

Brightness may vary a little with voltage variations, but shouldn't be
any more than the dash lights normally vary. If it's too much, you can
go to the voltage regulator (use the same setup, but put a 12V regulator
at the input of the whole thing, so you don't have to muck around with
changing all the resistor values), but I don't think that will be
necessary.

Actually, I'd be very surprised if all five original LEDs in the EQ were
actually fried; I'd expect it's more liklely just a broken connection
feeding them, or at worst, whatever was feeding them (probably a
resistor, maybe a resistor/transistor setup for a constant-current
supply) was toasted. I'd give the EQ a good going-over for a broken
circuit trace or loose wire before going to all the effort of rigging up
a completely separate display.


---
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Oh, wait. I think I get the diagram now. I hook up all the LED's in
parallel, but then I hook up the resistor IN SERIES with the 5 LED's.
RIGHT?

MOSFET

"Matt Ion" wrote in message
news:cEIOf.107123$sa3.93267@pd7tw1no...
MOSFET wrote:
I need help with some LEDs. I bought this Clarion dash-mount EQ on Ebay
and the blue LED's that illuminate all the dials were dead. I went to
Radio Shack and bought five 12 volt LED's and installed them into the
unit. They are NOT wired to any of the EQ wiring. They have their own
positive and negative leads coming out of the EQ (obviously, this is
something I did, not Clarion). Now this worked GREAT on my 13.5 volt
bench power supply. But in my car hooked up to my ignition voltage, it
SUCKS. It is CONSTANTLY changing brightness with engine voltage going
from nearly off when the car is idling to VERY BRIGHT when the car is at
a high RPM. I KNOW there must be a way to even-out this voltage, so it
maintains a CONSTANT 13 volts (it uses hardly any amperage, of course),
but I don't know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want to
as that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Alright, there's a lot of speculation and half-assed information floating
around here; let's try to clear a few things up. Note: this is based on
the assumption that these are just straight-up LEDs with no built-in
resistors or other circuitry (what is the RS part number?)

First, a voltage regulator is overkill. The problem you're having with
fluctuating brightness is because wiring them in series is dropping the
voltage across individual LEDs to below each one's forward voltage.

Any diode will not begin conducting current until the voltage reaches a
certain level: for germanium diodes, it's typically about .7V; for silicon
diodes it's 1.4V; and for LEDs it's usually around 2-3V. Once you reach
that voltage level, it will begin conducting the full voltage through with
next to no resistance to the current. That means if you just hook up an
LED across your car battery, it will appear as pretty much a dead short,
and will glow very very brightly... for a few milliseconds.

Now what you did in your orignal setup was to split the car's voltage
evenly across the five LEDs - if each one drops exacly 3V, then to run
them all, you need a solid 15V; any less, and the voltage per diode drops.
As it drops below the avalanche point, they'll stop conducting; if ONE
stops conducting, they ALL shut down.

So what you want to do is wire the LEDs in parallel, so each one gets the
full available voltage. Again, this will normally allow all available
current to flow through each one until they melt down, so you need to
limit the current with a resistor (or resistors). Most LEDs require
around 12-20mA, so using Ohm's Law, we can calculate, assuming an average
14V and a median 16mA (check the package specs):
14 volts / 0.016 amps = 875 ohms.

So an 875-ohm resistor in series with EACH LED will give you a good
mid-level brightness; now the closest standard resisitance to that is 820
ohms, which will be a little brigher, but not noticeably so; assume a 10%
tolerance and it's well within range. Figure 14V*0.016A=.224W, so a
quarter-watt unit will be fine (1/4W, 10% resistors are about the most
commonly available, so it makes for easy shopping).

You could simplify things a bit by using one resistor to feed all five in
parallel. Since this would require 5*16mA, or 80mA, you need
14V/0.08A=175 ohms total (or just do 875/5). A 150 or 180 ohm resistor
will do, but keep in mind, the power draw will increase accordingly, to
about 1.25W, so you'll want a resistor that will handle at least 1W.

So your wiring would look like this:

820ohm LED
+----/\/\/\/--||----+
+----/\/\/\/--||----+
+12V--+----/\/\/\/--||----+--ground
+----/\/\/\/--||----+
+----/\/\/\/--||----+

Or

+--||----+
150ohm +--||----+
+12V---/\/\/\/--+--||----+--ground
+--||----+
+--||----+

(Use a fixed-width font or the diagrams will look nasty)

Brightness may vary a little with voltage variations, but shouldn't be any
more than the dash lights normally vary. If it's too much, you can go to
the voltage regulator (use the same setup, but put a 12V regulator at the
input of the whole thing, so you don't have to muck around with changing
all the resistor values), but I don't think that will be necessary.

Actually, I'd be very surprised if all five original LEDs in the EQ were
actually fried; I'd expect it's more liklely just a broken connection
feeding them, or at worst, whatever was feeding them (probably a resistor,
maybe a resistor/transistor setup for a constant-current supply) was
toasted. I'd give the EQ a good going-over for a broken circuit trace or
loose wire before going to all the effort of rigging up a completely
separate display.


---
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LOL you're too much

In article , "MOSFET"
wrote:
Oh, wait. I think I get the diagram now. I hook up all the LED's in
parallel, but then I hook up the resistor IN SERIES with the 5 LED's.
RIGHT?

MOSFET

"Matt Ion" wrote in message
news:cEIOf.107123$sa3.93267@pd7tw1no...
MOSFET wrote:
I need help with some LEDs. I bought this Clarion dash-mount EQ on Ebay
and the blue LED's that illuminate all the dials were dead. I went to
Radio Shack and bought five 12 volt LED's and installed them into the
unit. They are NOT wired to any of the EQ wiring. They have their own
positive and negative leads coming out of the EQ (obviously, this is
something I did, not Clarion). Now this worked GREAT on my 13.5 volt
bench power supply. But in my car hooked up to my ignition voltage, it
SUCKS. It is CONSTANTLY changing brightness with engine voltage going
from nearly off when the car is idling to VERY BRIGHT when the car is at
a high RPM. I KNOW there must be a way to even-out this voltage, so it
maintains a CONSTANT 13 volts (it uses hardly any amperage, of course),
but I don't know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want to
as that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Alright, there's a lot of speculation and half-assed information floating
around here; let's try to clear a few things up. Note: this is based on
the assumption that these are just straight-up LEDs with no built-in
resistors or other circuitry (what is the RS part number?)

First, a voltage regulator is overkill. The problem you're having with
fluctuating brightness is because wiring them in series is dropping the
voltage across individual LEDs to below each one's forward voltage.

Any diode will not begin conducting current until the voltage reaches a
certain level: for germanium diodes, it's typically about .7V; for silicon
diodes it's 1.4V; and for LEDs it's usually around 2-3V. Once you reach
that voltage level, it will begin conducting the full voltage through with
next to no resistance to the current. That means if you just hook up an
LED across your car battery, it will appear as pretty much a dead short,
and will glow very very brightly... for a few milliseconds.

Now what you did in your orignal setup was to split the car's voltage
evenly across the five LEDs - if each one drops exacly 3V, then to run
them all, you need a solid 15V; any less, and the voltage per diode drops.
As it drops below the avalanche point, they'll stop conducting; if ONE
stops conducting, they ALL shut down.

So what you want to do is wire the LEDs in parallel, so each one gets the
full available voltage. Again, this will normally allow all available
current to flow through each one until they melt down, so you need to
limit the current with a resistor (or resistors). Most LEDs require
around 12-20mA, so using Ohm's Law, we can calculate, assuming an average
14V and a median 16mA (check the package specs):
14 volts / 0.016 amps = 875 ohms.

So an 875-ohm resistor in series with EACH LED will give you a good
mid-level brightness; now the closest standard resisitance to that is 820
ohms, which will be a little brigher, but not noticeably so; assume a 10%
tolerance and it's well within range. Figure 14V*0.016A=.224W, so a
quarter-watt unit will be fine (1/4W, 10% resistors are about the most
commonly available, so it makes for easy shopping).

You could simplify things a bit by using one resistor to feed all five in
parallel. Since this would require 5*16mA, or 80mA, you need
14V/0.08A=175 ohms total (or just do 875/5). A 150 or 180 ohm resistor
will do, but keep in mind, the power draw will increase accordingly, to
about 1.25W, so you'll want a resistor that will handle at least 1W.

So your wiring would look like this:

820ohm LED
+----/\/\/\/--||----+
+----/\/\/\/--||----+
+12V--+----/\/\/\/--||----+--ground
+----/\/\/\/--||----+
+----/\/\/\/--||----+

Or

+--||----+
150ohm +--||----+
+12V---/\/\/\/--+--||----+--ground
+--||----+
+--||----+

(Use a fixed-width font or the diagrams will look nasty)

Brightness may vary a little with voltage variations, but shouldn't be any
more than the dash lights normally vary. If it's too much, you can go to
the voltage regulator (use the same setup, but put a 12V regulator at the
input of the whole thing, so you don't have to muck around with changing
all the resistor values), but I don't think that will be necessary.

Actually, I'd be very surprised if all five original LEDs in the EQ were
actually fried; I'd expect it's more liklely just a broken connection
feeding them, or at worst, whatever was feeding them (probably a resistor,
maybe a resistor/transistor setup for a constant-current supply) was
toasted. I'd give the EQ a good going-over for a broken circuit trace or
loose wire before going to all the effort of rigging up a completely
separate display.


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http://www.avast.com

Like I said, you need to view using a non-proportional/fixed-width
font, like System or Courier, or the diagrams get all mucked up.

No Sweat! I'll just go to Non-Proportional/Fixed-Width-Fonts-R-US and pick
one up! Thanks!

MOSFET

"Matt Ion" wrote in message
news:j9SOf.109417$B94.86727@pd7tw3no...
MOSFET wrote:
Like I said, you need to view using a non-proportional/fixed-width
font, like System or Courier, or the diagrams get all mucked up.


No Sweat! I'll just go to Non-Proportional/Fixed-Width-Fonts-R-US and
pick one up! Thanks!

Those are fonts that have been included in every version of Windows ever
made, BTW. Just change the "Read message" font in Outlook Express. It's
not difficult.

Thanks. I was in a silly mood when I wrote that.

MOSFET

Wow. You're right, when I changed the font to "Fixed Width" it suddenly was
obvious how to wire it.

Thanks Matt. I REALLY appreciate all your help. You ROCK!

MOSFET

Thank you again!

MOSFET

"Matt Ion" wrote in message
news:17%Of.111381$B94.9246@pd7tw3no...
MOSFET wrote:
When I have the EQ opened up, I think I would like to add a sixth LED
(Radio Shack only had five on hand at the time), what value resistor
should I use for six LED's?

What value resistor did you actually use? You're probably okay with it as
is, it may dim all the LEDs slightly... if it's too dim, something about
20-30 ohms less should suffice.


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Matt Ion wrote:
Phonedude wrote:
"Captain Howdy" wrote in message
...

Your alternator already has a 14.5 volt regulator, so adding a 5 volt
regulator plus as resistor has the advantage of what, other then using a
lower
value of resistor? What is your point I'm all ears ? lol


From your attitude I doubt you'll care what I say, but a solid state voltage
regulater is a very common device used to deliver a fixed voltage. It will
provide a solid 5 volts to the led array regardless of how much the
alternator voltage goes up and down as the rpm change and the load changes.
As long as the input is greater than 5 volts, of course. The orignal poster
complained of the brightness changing as the voltage from his alternator
changed. This will solve the problem efficiently and solidly. A simple
resistor will not.

Umm, actually, it will... and already did, according to MOSFET. The
trick is in wiring the LEDs properly, which he didn't do in the first place.

Here's a simple reference explaining why it is better to use a
regulator.

http://www.theledlight.com/samplecircuits.html

You can usually jury rig anything to work, but for a couple of bucks
why not do it the best way you can?

PD

In article .com, "Phonedude" wrote:

Matt Ion wrote:
Phonedude wrote:
"Captain Howdy" wrote in message
...

Your alternator already has a 14.5 volt regulator, so adding a 5 volt
regulator plus as resistor has the advantage of what, other then using a
lower
value of resistor? What is your point I'm all ears ? lol


From your attitude I doubt you'll care what I say, but a solid state
voltage
regulater is a very common device used to deliver a fixed voltage. It will
provide a solid 5 volts to the led array regardless of how much the
alternator voltage goes up and down as the rpm change and the load changes.
As long as the input is greater than 5 volts, of course. The orignal
poster
complained of the brightness changing as the voltage from his alternator
changed. This will solve the problem efficiently and solidly. A simple
resistor will not.

Umm, actually, it will... and already did, according to MOSFET. The
trick is in wiring the LEDs properly, which he didn't do in the first place.

Here's a simple reference explaining why it is better to use a
regulator.

http://www.theledlight.com/samplecircuits.html

You can usually jury rig anything to work, but for a couple of bucks
why not do it the best way you can?

The reason for the big change in brightness was opperating too close to
the LED dropping voltage. If a parallel series system is wired with the resistors,
the brightness will change, but not that much.

By the way, I have 9 LED's witred series parallel within a 1 in square, doing an experiment.
The thing is, they are 5 watt LED's. Thats 45 watts!!!!! But I have special
cooling applied.

greg

"GregS" wrote in message
...
In article .com,
"Phonedude" wrote:

Matt Ion wrote:
Phonedude wrote:
"Captain Howdy" wrote in message
...

Your alternator already has a 14.5 volt regulator, so adding a 5 volt
regulator plus as resistor has the advantage of what, other then using
a
lower
value of resistor? What is your point I'm all ears ? lol


From your attitude I doubt you'll care what I say, but a solid state
voltage
regulater is a very common device used to deliver a fixed voltage. It
will
provide a solid 5 volts to the led array regardless of how much the
alternator voltage goes up and down as the rpm change and the load
changes.
As long as the input is greater than 5 volts, of course. The orignal
poster
complained of the brightness changing as the voltage from his
alternator
changed. This will solve the problem efficiently and solidly. A
simple
resistor will not.

Umm, actually, it will... and already did, according to MOSFET. The
trick is in wiring the LEDs properly, which he didn't do in the first
place.

Here's a simple reference explaining why it is better to use a
regulator.

http://www.theledlight.com/samplecircuits.html

You can usually jury rig anything to work, but for a couple of bucks
why not do it the best way you can?

The reason for the big change in brightness was opperating too close to
the LED dropping voltage. If a parallel series system is wired with the
resistors,
the brightness will change, but not that much.

By the way, I have 9 LED's witred series parallel within a 1 in square,
doing an experiment.
The thing is, they are 5 watt LED's. Thats 45 watts!!!!! But I have
special
cooling applied.

Yes the brightness would be ok, but there is more to it than that. A steady
12v will result in longer life for your LEDs and eliminate potential damage
from the spikes and such generated when you turn accessories such as your
air conditioner on and off. It's no big deal either way, but for and
expense of about $2.00 why not do it right in the first place? I originally
recommended a 5v regulator, but a 12v one makes more sense -- it will
generate very little heat because it is not dropping that much voltage.
Same cost, same application.

PD

In article JL%Pf.40838$%I.27033@trnddc03, "Phonedude" wrote:

"GregS" wrote in message
...
In article .com,
"Phonedude" wrote:

Matt Ion wrote:
Phonedude wrote:
"Captain Howdy" wrote in message
...

Your alternator already has a 14.5 volt regulator, so adding a 5 volt
regulator plus as resistor has the advantage of what, other then using
a
lower
value of resistor? What is your point I'm all ears ? lol


From your attitude I doubt you'll care what I say, but a solid state
voltage
regulater is a very common device used to deliver a fixed voltage. It
will
provide a solid 5 volts to the led array regardless of how much the
alternator voltage goes up and down as the rpm change and the load
changes.
As long as the input is greater than 5 volts, of course. The orignal
poster
complained of the brightness changing as the voltage from his
alternator
changed. This will solve the problem efficiently and solidly. A
simple
resistor will not.

Umm, actually, it will... and already did, according to MOSFET. The
trick is in wiring the LEDs properly, which he didn't do in the first
place.

Here's a simple reference explaining why it is better to use a
regulator.

http://www.theledlight.com/samplecircuits.html

You can usually jury rig anything to work, but for a couple of bucks
why not do it the best way you can?

The reason for the big change in brightness was opperating too close to
the LED dropping voltage. If a parallel series system is wired with the
resistors,
the brightness will change, but not that much.

By the way, I have 9 LED's witred series parallel within a 1 in square,
doing an experiment.
The thing is, they are 5 watt LED's. Thats 45 watts!!!!! But I have
special
cooling applied.

Yes the brightness would be ok, but there is more to it than that. A steady
12v will result in longer life for your LEDs and eliminate potential damage
from the spikes and such generated when you turn accessories such as your
air conditioner on and off. It's no big deal either way, but for and
expense of about $2.00 why not do it right in the first place? I originally
recommended a 5v regulator, but a 12v one makes more sense -- it will
generate very little heat because it is not dropping that much voltage.
Same cost, same application.

Should work OK. Use a low dropout regulator. It only starts to regulate
if you get a minimum voltage over 12. A low dropout regulator minimizes the
excess voltage needed for the thing to start regulating.
greg

That would be 0.3 Volts for Germanium, 0.5 or so for Silicon, 1 - 1.7 for
LED's to start conducting.
For the Radio shack LEDs I'd assume about 1.5 Volts. Doesn't really matter
much. 10 mA is a good current for 3mm's, not too low with 5mm's. In your
car, you have about 14.5 volts available. Subtract the 1.5 volts the diode
needs to start conducting, and you are at 13V. 10 mA requires a 1300 Ohm
resistor. If you have five LEDs, you need five resistors of 1300 Ohms or one
resistor of 260 Ohms. I suppose 220 Ohms will be pretty darn good. 150 Ohms
is OK too. About 59 mA will flow through this affair. That calculates out to
about .77 Watts. Take at least a 5 Watt resistor, unless you just like hot
stuff (who doesn't?). Now you have a resistor that will last, about 11 mA
per LED which will make them happy and last long. If you go with five 1300
Ohm resistors, take a 1 Watt resistor ea. All in parallel.


"Matt Ion" wrote in message
news:cEIOf.107123$sa3.93267@pd7tw1no...
MOSFET wrote:
I need help with some LEDs. I bought this Clarion dash-mount EQ on Ebay
and the blue LED's that illuminate all the dials were dead. I went to
Radio Shack and bought five 12 volt LED's and installed them into the
unit. They are NOT wired to any of the EQ wiring. They have their own
positive and negative leads coming out of the EQ (obviously, this is
something I did, not Clarion). Now this worked GREAT on my 13.5 volt
bench power supply. But in my car hooked up to my ignition voltage, it
SUCKS. It is CONSTANTLY changing brightness with engine voltage going
from nearly off when the car is idling to VERY BRIGHT when the car is at
a high RPM. I KNOW there must be a way to even-out this voltage, so it
maintains a CONSTANT 13 volts (it uses hardly any amperage, of course),
but I don't know how to do it.

Also, should I use the REM wire from the HU for power? I didn't want to
as that wire must already activate the EQ and four amps.

Any help would be GREATLY appreciated.

Alright, there's a lot of speculation and half-assed information floating
around here; let's try to clear a few things up. Note: this is based on
the assumption that these are just straight-up LEDs with no built-in
resistors or other circuitry (what is the RS part number?)

First, a voltage regulator is overkill. The problem you're having with
fluctuating brightness is because wiring them in series is dropping the
voltage across individual LEDs to below each one's forward voltage.

Any diode will not begin conducting current until the voltage reaches a
certain level: for germanium diodes, it's typically about .7V; for silicon
diodes it's 1.4V; and for LEDs it's usually around 2-3V. Once you reach
that voltage level, it will begin conducting the full voltage through with
next to no resistance to the current. That means if you just hook up an
LED across your car battery, it will appear as pretty much a dead short,
and will glow very very brightly... for a few milliseconds.

Now what you did in your orignal setup was to split the car's voltage
evenly across the five LEDs - if each one drops exacly 3V, then to run
them all, you need a solid 15V; any less, and the voltage per diode drops.
As it drops below the avalanche point, they'll stop conducting; if ONE
stops conducting, they ALL shut down.

So what you want to do is wire the LEDs in parallel, so each one gets the
full available voltage. Again, this will normally allow all available
current to flow through each one until they melt down, so you need to
limit the current with a resistor (or resistors). Most LEDs require
around 12-20mA, so using Ohm's Law, we can calculate, assuming an average
14V and a median 16mA (check the package specs):
14 volts / 0.016 amps = 875 ohms.

So an 875-ohm resistor in series with EACH LED will give you a good
mid-level brightness; now the closest standard resisitance to that is 820
ohms, which will be a little brigher, but not noticeably so; assume a 10%
tolerance and it's well within range. Figure 14V*0.016A=.224W, so a
quarter-watt unit will be fine (1/4W, 10% resistors are about the most
commonly available, so it makes for easy shopping).

You could simplify things a bit by using one resistor to feed all five in
parallel. Since this would require 5*16mA, or 80mA, you need
14V/0.08A=175 ohms total (or just do 875/5). A 150 or 180 ohm resistor
will do, but keep in mind, the power draw will increase accordingly, to
about 1.25W, so you'll want a resistor that will handle at least 1W.

So your wiring would look like this:

820ohm LED
+----/\/\/\/--||----+
+----/\/\/\/--||----+
+12V--+----/\/\/\/--||----+--ground
+----/\/\/\/--||----+
+----/\/\/\/--||----+

Or

+--||----+
150ohm +--||----+
+12V---/\/\/\/--+--||----+--ground
+--||----+
+--||----+

(Use a fixed-width font or the diagrams will look nasty)

Brightness may vary a little with voltage variations, but shouldn't be any
more than the dash lights normally vary. If it's too much, you can go to
the voltage regulator (use the same setup, but put a 12V regulator at the
input of the whole thing, so you don't have to muck around with changing
all the resistor values), but I don't think that will be necessary.

Actually, I'd be very surprised if all five original LEDs in the EQ were
actually fried; I'd expect it's more liklely just a broken connection
feeding them, or at worst, whatever was feeding them (probably a resistor,
maybe a resistor/transistor setup for a constant-current supply) was
toasted. I'd give the EQ a good going-over for a broken circuit trace or
loose wire before going to all the effort of rigging up a completely
separate display.


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