I'm working on a project that has a power supply requirement very similar to
a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used, such as
a resistor shunted by a time-delay relay?

Robert Morein wrote:

I'm working on a project that has a power supply requirement very similar to
a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used, such as
a resistor shunted by a time-delay relay?



Answering the second question, I've done quite well with a thermistor in
the primary of a transformer for an audio amp where it is about 16 ohms
cold and 1 ohm hot. A relay would work but make sure it does not time
out before the caps charge or it's pointless.

You should be able to determine a suitable limit for the diode by
assuming it is feeding a short as that's what a very large uncharged cap
will look like. Probably use 50v divided by the resistance of the power
transformer secondary as the current requirement. Someone is sure to
correct me if I'm wrong about this.

Robert Morein wrote:

I'm working on a project that has a power supply requirement very similar to
a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used, such as
a resistor shunted by a time-delay relay?



Answering the second question, I've done quite well with a thermistor in
the primary of a transformer for an audio amp where it is about 16 ohms
cold and 1 ohm hot. A relay would work but make sure it does not time
out before the caps charge or it's pointless.

You should be able to determine a suitable limit for the diode by
assuming it is feeding a short as that's what a very large uncharged cap
will look like. Probably use 50v divided by the resistance of the power
transformer secondary as the current requirement. Someone is sure to
correct me if I'm wrong about this.

Robert Morein wrote:

I'm working on a project that has a power supply requirement very similar to
a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used, such as
a resistor shunted by a time-delay relay?



Answering the second question, I've done quite well with a thermistor in
the primary of a transformer for an audio amp where it is about 16 ohms
cold and 1 ohm hot. A relay would work but make sure it does not time
out before the caps charge or it's pointless.

You should be able to determine a suitable limit for the diode by
assuming it is feeding a short as that's what a very large uncharged cap
will look like. Probably use 50v divided by the resistance of the power
transformer secondary as the current requirement. Someone is sure to
correct me if I'm wrong about this.

Robert Morein wrote:

I'm working on a project that has a power supply requirement very similar to
a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used, such as
a resistor shunted by a time-delay relay?



Answering the second question, I've done quite well with a thermistor in
the primary of a transformer for an audio amp where it is about 16 ohms
cold and 1 ohm hot. A relay would work but make sure it does not time
out before the caps charge or it's pointless.

You should be able to determine a suitable limit for the diode by
assuming it is feeding a short as that's what a very large uncharged cap
will look like. Probably use 50v divided by the resistance of the power
transformer secondary as the current requirement. Someone is sure to
correct me if I'm wrong about this.

In , on 01/20/04
at 10:16 PM, "Robert Morein" said:

I'm working on a project that has a power supply requirement very
similar to a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used,
such as a resistor shunted by a time-delay relay?

At the instant power is supplied, the capacitor appears as a short
circuit (plus any internal capacitor resistance). Current through the
diode will be limited only by the transformer resistance, diode
resistance, and the circuit wiring resistance (including the
capacitor).

Obviously, you want to limit the average and initial charging currents
to something the diode is happy about, however, there is another sneaky
diode limit that you should be aware of. Current will flow to your
capacitor bank only when the supply voltage is higher than the
capacitor voltage (plus the diode voltage drop). This means that all of
the current necessary to replenish the charge (depleted each half cycle
of the the power line by the load circuit) must flow at the power line
peaks. Even though the average current could be quite reasonable, the
peak current could be too high. Check your design to make sure the
diode's "repetitive peak current" spec is met. (Anytime the diode
switches on, instantaneous current is essentially limited only by the
external circuit.)

You may have to go through several iterations on your design to make
sure that you can deliver the required average current, at the required
ripple, while respecting your diode's limits.

Zero ripple is not possible, very low ripple may not be practical or
required. Look at the "power line rejection" spec of your circuit. Many
circuits are not particularly sensitive to power supply ripple.

If you need extremely low ripple, consider adding an active regular, a
series inductor, or a secondary regulator for sections of the circuit
that are sensitive to ripple.

---

While a large capacitor makes one feel all warm and fuzzy (after all --
bigger is better *IS* the American way), but it is not always the best
idea. Years ago I ordered some CRT terminals that had a very impressive
looking power supply. Unfortunately, it exceeded the repetitive peak
diode current spec. It took a while for the company to figure it out.
It was warranty repair and it must have been expensive for them. The
first repair they just replaced the diode. The second repair they used
a *MUCH* larger, impressive looking diode. The third, and thankfully
final repair, they replaced the diode again and added a small series
resistor. These failures were not immediate, it took several weeks and
the larger diode survived somewhat longer.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

In , on 01/20/04
at 10:16 PM, "Robert Morein" said:

I'm working on a project that has a power supply requirement very
similar to a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used,
such as a resistor shunted by a time-delay relay?

At the instant power is supplied, the capacitor appears as a short
circuit (plus any internal capacitor resistance). Current through the
diode will be limited only by the transformer resistance, diode
resistance, and the circuit wiring resistance (including the
capacitor).

Obviously, you want to limit the average and initial charging currents
to something the diode is happy about, however, there is another sneaky
diode limit that you should be aware of. Current will flow to your
capacitor bank only when the supply voltage is higher than the
capacitor voltage (plus the diode voltage drop). This means that all of
the current necessary to replenish the charge (depleted each half cycle
of the the power line by the load circuit) must flow at the power line
peaks. Even though the average current could be quite reasonable, the
peak current could be too high. Check your design to make sure the
diode's "repetitive peak current" spec is met. (Anytime the diode
switches on, instantaneous current is essentially limited only by the
external circuit.)

You may have to go through several iterations on your design to make
sure that you can deliver the required average current, at the required
ripple, while respecting your diode's limits.

Zero ripple is not possible, very low ripple may not be practical or
required. Look at the "power line rejection" spec of your circuit. Many
circuits are not particularly sensitive to power supply ripple.

If you need extremely low ripple, consider adding an active regular, a
series inductor, or a secondary regulator for sections of the circuit
that are sensitive to ripple.

---

While a large capacitor makes one feel all warm and fuzzy (after all --
bigger is better *IS* the American way), but it is not always the best
idea. Years ago I ordered some CRT terminals that had a very impressive
looking power supply. Unfortunately, it exceeded the repetitive peak
diode current spec. It took a while for the company to figure it out.
It was warranty repair and it must have been expensive for them. The
first repair they just replaced the diode. The second repair they used
a *MUCH* larger, impressive looking diode. The third, and thankfully
final repair, they replaced the diode again and added a small series
resistor. These failures were not immediate, it took several weeks and
the larger diode survived somewhat longer.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

In , on 01/20/04
at 10:16 PM, "Robert Morein" said:

I'm working on a project that has a power supply requirement very
similar to a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used,
such as a resistor shunted by a time-delay relay?

At the instant power is supplied, the capacitor appears as a short
circuit (plus any internal capacitor resistance). Current through the
diode will be limited only by the transformer resistance, diode
resistance, and the circuit wiring resistance (including the
capacitor).

Obviously, you want to limit the average and initial charging currents
to something the diode is happy about, however, there is another sneaky
diode limit that you should be aware of. Current will flow to your
capacitor bank only when the supply voltage is higher than the
capacitor voltage (plus the diode voltage drop). This means that all of
the current necessary to replenish the charge (depleted each half cycle
of the the power line by the load circuit) must flow at the power line
peaks. Even though the average current could be quite reasonable, the
peak current could be too high. Check your design to make sure the
diode's "repetitive peak current" spec is met. (Anytime the diode
switches on, instantaneous current is essentially limited only by the
external circuit.)

You may have to go through several iterations on your design to make
sure that you can deliver the required average current, at the required
ripple, while respecting your diode's limits.

Zero ripple is not possible, very low ripple may not be practical or
required. Look at the "power line rejection" spec of your circuit. Many
circuits are not particularly sensitive to power supply ripple.

If you need extremely low ripple, consider adding an active regular, a
series inductor, or a secondary regulator for sections of the circuit
that are sensitive to ripple.

---

While a large capacitor makes one feel all warm and fuzzy (after all --
bigger is better *IS* the American way), but it is not always the best
idea. Years ago I ordered some CRT terminals that had a very impressive
looking power supply. Unfortunately, it exceeded the repetitive peak
diode current spec. It took a while for the company to figure it out.
It was warranty repair and it must have been expensive for them. The
first repair they just replaced the diode. The second repair they used
a *MUCH* larger, impressive looking diode. The third, and thankfully
final repair, they replaced the diode again and added a small series
resistor. These failures were not immediate, it took several weeks and
the larger diode survived somewhat longer.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

In , on 01/20/04
at 10:16 PM, "Robert Morein" said:

I'm working on a project that has a power supply requirement very
similar to a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used,
such as a resistor shunted by a time-delay relay?

At the instant power is supplied, the capacitor appears as a short
circuit (plus any internal capacitor resistance). Current through the
diode will be limited only by the transformer resistance, diode
resistance, and the circuit wiring resistance (including the
capacitor).

Obviously, you want to limit the average and initial charging currents
to something the diode is happy about, however, there is another sneaky
diode limit that you should be aware of. Current will flow to your
capacitor bank only when the supply voltage is higher than the
capacitor voltage (plus the diode voltage drop). This means that all of
the current necessary to replenish the charge (depleted each half cycle
of the the power line by the load circuit) must flow at the power line
peaks. Even though the average current could be quite reasonable, the
peak current could be too high. Check your design to make sure the
diode's "repetitive peak current" spec is met. (Anytime the diode
switches on, instantaneous current is essentially limited only by the
external circuit.)

You may have to go through several iterations on your design to make
sure that you can deliver the required average current, at the required
ripple, while respecting your diode's limits.

Zero ripple is not possible, very low ripple may not be practical or
required. Look at the "power line rejection" spec of your circuit. Many
circuits are not particularly sensitive to power supply ripple.

If you need extremely low ripple, consider adding an active regular, a
series inductor, or a secondary regulator for sections of the circuit
that are sensitive to ripple.

---

While a large capacitor makes one feel all warm and fuzzy (after all --
bigger is better *IS* the American way), but it is not always the best
idea. Years ago I ordered some CRT terminals that had a very impressive
looking power supply. Unfortunately, it exceeded the repetitive peak
diode current spec. It took a while for the company to figure it out.
It was warranty repair and it must have been expensive for them. The
first repair they just replaced the diode. The second repair they used
a *MUCH* larger, impressive looking diode. The third, and thankfully
final repair, they replaced the diode again and added a small series
resistor. These failures were not immediate, it took several weeks and
the larger diode survived somewhat longer.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

Barry Mann wrote:

[sorry about the puzzle, spammers are ruining my mailbox]

Try spamihilator!


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

Barry Mann wrote:

[sorry about the puzzle, spammers are ruining my mailbox]

Try spamihilator!


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

Barry Mann wrote:

[sorry about the puzzle, spammers are ruining my mailbox]

Try spamihilator!


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

Barry Mann wrote:

[sorry about the puzzle, spammers are ruining my mailbox]

Try spamihilator!


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

It's not the filter capacitance that determines the proper rectifier
amperage but the current draw of the circuit(s) you are supplying. I have
used an inrush current limiting resistor that was bypassed by a relay that
activated when the voltage at the caps reached 90% or so of full voltage.
Low tech but effective.
Wayne


"Robert Morein" wrote in message
...
I'm working on a project that has a power supply requirement very similar
to
a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used, such
as
a resistor shunted by a time-delay relay?

It's not the filter capacitance that determines the proper rectifier
amperage but the current draw of the circuit(s) you are supplying. I have
used an inrush current limiting resistor that was bypassed by a relay that
activated when the voltage at the caps reached 90% or so of full voltage.
Low tech but effective.
Wayne


"Robert Morein" wrote in message
...
I'm working on a project that has a power supply requirement very similar
to
a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used, such
as
a resistor shunted by a time-delay relay?

It's not the filter capacitance that determines the proper rectifier
amperage but the current draw of the circuit(s) you are supplying. I have
used an inrush current limiting resistor that was bypassed by a relay that
activated when the voltage at the caps reached 90% or so of full voltage.
Low tech but effective.
Wayne


"Robert Morein" wrote in message
...
I'm working on a project that has a power supply requirement very similar
to
a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used, such
as
a resistor shunted by a time-delay relay?

It's not the filter capacitance that determines the proper rectifier
amperage but the current draw of the circuit(s) you are supplying. I have
used an inrush current limiting resistor that was bypassed by a relay that
activated when the voltage at the caps reached 90% or so of full voltage.
Low tech but effective.
Wayne


"Robert Morein" wrote in message
...
I'm working on a project that has a power supply requirement very similar
to
a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used, such
as
a resistor shunted by a time-delay relay?

In , on 01/22/04
at 05:33 AM, Peter Larsen said:

[ ... ]

Try spamihilator!

[ ... ]

Unless it's Java based I'm not using a platform that would allow me to
run it.

It's amazing how many times I've been chided for using my puzzle. I
thought technical types would enjoy it.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

In , on 01/22/04
at 05:33 AM, Peter Larsen said:

[ ... ]

Try spamihilator!

[ ... ]

Unless it's Java based I'm not using a platform that would allow me to
run it.

It's amazing how many times I've been chided for using my puzzle. I
thought technical types would enjoy it.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

In , on 01/22/04
at 05:33 AM, Peter Larsen said:

[ ... ]

Try spamihilator!

[ ... ]

Unless it's Java based I'm not using a platform that would allow me to
run it.

It's amazing how many times I've been chided for using my puzzle. I
thought technical types would enjoy it.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

In , on 01/22/04
at 05:33 AM, Peter Larsen said:

[ ... ]

Try spamihilator!

[ ... ]

Unless it's Java based I'm not using a platform that would allow me to
run it.

It's amazing how many times I've been chided for using my puzzle. I
thought technical types would enjoy it.

-----------------------------------------------------------
spam:
wordgame:123(abc):14 9 20 5 2 9 18 4 at 22 15 9 3 5 14 5 20 dot 3 15
13 (Barry Mann)
[sorry about the puzzle, spammers are ruining my mailbox]
-----------------------------------------------------------

"Robert Morein" wrote in message
...
I'm working on a project that has a power supply requirement very similar
to
a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used, such
as
a resistor shunted by a time-delay relay?



yes they get hot, and when something fails SMOKE.
try using PWM to charge up your caps, much safer.
600VA Toroidals blow 13amp mains fuses with ease.
if you are making an EMP device dont,
you wont be popular with your neighbours.
regards malcolm

"Robert Morein" wrote in message
...
I'm working on a project that has a power supply requirement very similar
to
a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used, such
as
a resistor shunted by a time-delay relay?



yes they get hot, and when something fails SMOKE.
try using PWM to charge up your caps, much safer.
600VA Toroidals blow 13amp mains fuses with ease.
if you are making an EMP device dont,
you wont be popular with your neighbours.
regards malcolm

"Robert Morein" wrote in message
...
I'm working on a project that has a power supply requirement very similar
to
a large audio amplifier.
There will be 104K ufd at 50V.

What amperage rectifiers are found in amplifiers with equivalent power
supply capacitance?
Has anyone seen cases where surge inrush limiting circuits are used, such
as
a resistor shunted by a time-delay relay?



yes they get hot, and when something fails SMOKE.
try using PWM to charge up your caps, much safer.
600VA Toroidals blow 13amp mains fuses with ease.
if you are making an EMP device dont,
you wont be popular with your neighbours.
regards malcolm