I am unsure how a diode is supposed to be connected across of a relay.
I have taken a picture of how I might do it, but I am not certain if
this is the correct way of doing it. Can someone take a look?

http://fstor486.i8.com/DiodeRelay1.jpg

Should the diode be connected (soldered) to the relay terminal holes or
what??

On the relay, wherever the + and - wires are connected to it, thats where
you solder the diode to. Solder the wire closest to the line on the diode to
the + wire and the other wire on the diode to the - wire.


"RJ" wrote in message
ups.com...
I am unsure how a diode is supposed to be connected across of a relay.
I have taken a picture of how I might do it, but I am not certain if
this is the correct way of doing it. Can someone take a look?

http://fstor486.i8.com/DiodeRelay1.jpg

Should the diode be connected (soldered) to the relay terminal holes or
what??

It should be soldered reverse biased across the coil leads of the relay. In
other words, the line drawn on the diode should be soldered to the part of
the coil where you attach the 12v lead, and the other side to the part of
the coil where you attach the ground.

But a more important question is: what are you using the relay for? The
picture looks like you're using a bosch type relay. Don't they usually come
with diodes already installed? Not sure what use Bosch relays are in car
audio. Are you doing an alarm or something?


"RJ" wrote in message
ups.com...
I am unsure how a diode is supposed to be connected across of a relay.
I have taken a picture of how I might do it, but I am not certain if
this is the correct way of doing it. Can someone take a look?

http://fstor486.i8.com/DiodeRelay1.jpg

Should the diode be connected (soldered) to the relay terminal holes or
what??

MZ wrote:
It should be soldered reverse biased across the coil leads of the
relay. In
other words, the line drawn on the diode should be soldered to the
part of
the coil where you attach the 12v lead, and the other side to the
part of
the coil where you attach the ground.

But a more important question is: what are you using the relay for?
The
picture looks like you're using a bosch type relay. Don't they
usually come
with diodes already installed? Not sure what use Bosch relays are in
car
audio. Are you doing an alarm or something?

The reason I am using a relay and a diode is because I need to turn on
2 amplifiers, and I read on this newsgroup that one should use a relay
(and a diode) to protect the headunit's remote turn on lead/circuit
from burning out due to EMF kickback. I really don't want to ruin my
headunit.

The reason I am using a relay and a diode is because I need to turn on
2 amplifiers, and I read on this newsgroup that one should use a relay
(and a diode) to protect the headunit's remote turn on lead/circuit
from burning out due to EMF kickback. I really don't want to ruin my
headunit.

Then you're going about things the wrong way. That type of relay probably
has something like a 50 ohm coil or less. Typical for most Bosch relays.
That means it's going to attempt to draw about 250 amps or more from the
head unit. That's the equivalent of having 5 or more amplifiers hooked up
to the remote terminal.

You don't need a relay for only 2 amplifiers anyway. But if you insist on
using one, get one of the little blue relays from Radio Shack. The small
ones have coils rated at a few hundred ohms I think.

That means it's going to attempt to draw about 250 amps or more from the
head unit.

Oops. That should read "milliamps"...

"MZ" wrote in message
news
The reason I am using a relay and a diode is because I need to turn on
2 amplifiers, and I read on this newsgroup that one should use a relay
(and a diode) to protect the headunit's remote turn on lead/circuit
from burning out due to EMF kickback. I really don't want to ruin my
headunit.

Then you're going about things the wrong way. That type of relay probably
has something like a 50 ohm coil or less. Typical for most Bosch relays.
That means it's going to attempt to draw about 250 amps or more from the
head unit. That's the equivalent of having 5 or more amplifiers hooked up
to the remote terminal.


Milliamps, I think you meant.

You don't need a relay for only 2 amplifiers anyway. But if you insist on
using one, get one of the little blue relays from Radio Shack. The small
ones have coils rated at a few hundred ohms I think.


I agree with MZ, you don't need a relay for 2 amps. Heck, I use to run 3
amps and a crossover off a remote lead. I finally went to a relay when I
was running 12V fans that came on when the system came on. They ran off the
switch power through a relay that was closed by the remote lead.

-Bruce

MZ wrote:
The reason I am using a relay and a diode is because I need to turn
on
2 amplifiers, and I read on this newsgroup that one should use a
relay
(and a diode) to protect the headunit's remote turn on lead/circuit
from burning out due to EMF kickback. I really don't want to ruin
my
headunit.

Then you're going about things the wrong way. That type of relay
probably
has something like a 50 ohm coil or less. Typical for most Bosch
relays.
That means it's going to attempt to draw about 250 amps or more from
the
head unit. That's the equivalent of having 5 or more amplifiers
hooked up
to the remote terminal.


Wha?? Are you saying that I could cause damage to the headunit using
the Bosch relay? Why is this type of relay suggested for use for remote
turn on leads on many car audio web sites? I think the RAC FAQ even
says it's ok to use this type of relay. This is the first time I've
heard otherwise...

You can't damage a head unit using a relay on the remote turn on lead as
long as you fuse it. The only way you'll damage the turn on lead is
that if you short it.


--
Vestax05pro


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Wha?? Are you saying that I could cause damage to the headunit using
the Bosch relay? Why is this type of relay suggested for use for remote
turn on leads on many car audio web sites? I think the RAC FAQ even
says it's ok to use this type of relay. This is the first time I've
heard otherwise...

You're using a relay because you don't want to draw too much current from
the remote lead of the head unit, correct? The problem with your strategy,
however, is that the relay you're using is drawing more current from the
head unit than five amplifiers would. Will it damage your head unit?
Probably not, but it's been known to happen.

I don't believe the Bosch relay is recommended in the RAC FAQ. If it is,
I'll be sure to contact Ian to get that removed. Anyway, I recommend
bcae1.com as the most comprehensive and technically accurate car audio
website on the net. In the author's relay section, he writes:

"It's been mentioned quite a few times that the Bosch relay's coil has a
fairly low resistance (~75 ohms). It has also been suggested that you could
use a different relay with significantly more coil resistance so that you
draw less current from the remote output of the head unit. The relay below
is from Radio Shack. Its stock number is 275-248. It has a coil resistance
of ~400 ohms which means that it will draw ~1/5 the amount of current of the
Bosch relay. In the following image, the red wire is the fused power source
(10A max - even less for small wire like I've used). The blue wire is the
remote from the head unit. The black wire goes to ground. The green wire
goes to the remote input of the amplifiers and to fans if you have them."

In article .com,
"RJ" wrote:

MZ wrote:
It should be soldered reverse biased across the coil leads of the
relay. In
other words, the line drawn on the diode should be soldered to the
part of
the coil where you attach the 12v lead, and the other side to the
part of
the coil where you attach the ground.

But a more important question is: what are you using the relay for?
The
picture looks like you're using a bosch type relay. Don't they
usually come
with diodes already installed? Not sure what use Bosch relays are in
car
audio. Are you doing an alarm or something?

The reason I am using a relay and a diode is because I need to turn on
2 amplifiers, and I read on this newsgroup that one should use a relay
(and a diode) to protect the headunit's remote turn on lead/circuit
from burning out due to EMF kickback. I really don't want to ruin my
headunit.

Most amplifiers draw just a few mA, and that's mostly to drain away
stray charges. An automotive relay draws at least 100mA.

"Kevin McMurtrie" wrote in message
...
In article .com,
"RJ" wrote:

MZ wrote:
It should be soldered reverse biased across the coil leads of the
relay. In
other words, the line drawn on the diode should be soldered to the
part of
the coil where you attach the 12v lead, and the other side to the
part of
the coil where you attach the ground.

But a more important question is: what are you using the relay for?
The
picture looks like you're using a bosch type relay. Don't they
usually come
with diodes already installed? Not sure what use Bosch relays are in
car
audio. Are you doing an alarm or something?

The reason I am using a relay and a diode is because I need to turn on
2 amplifiers, and I read on this newsgroup that one should use a relay
(and a diode) to protect the headunit's remote turn on lead/circuit
from burning out due to EMF kickback. I really don't want to ruin my
headunit.

Most amplifiers draw just a few mA, and that's mostly to drain away
stray charges. An automotive relay draws at least 100mA.

What he said, the only draw on the amp is the resistance of the dropping
resistor on the remote input. It would be nil without the resistor but
could "float" up and turn on the amp. Remember the remote turn on just
turns on a P-N junction on the amp in paralell to a dropping resistor to
ground.

The remote output of the head is usually only a small case darlington
output. If one wanted more current you could build a solid state relay from
larger case darlingtons like a TIP102 or several in tandem. These devices
can handle hella current in tandem.

Chad