How low can I go for VDC rating of this cap? (schematic attached)

[JW]

This is an example of one of the program outputs on my console. The cap on the schematic is a 100uF/25V  bi  polar. I'm trying to increase this cap to 470uF like API, but wondering if I can lower the voltage to accommodate for size issue.

In the input strip in this same spot (after the output opamp) the cap is in reality a 100uF/16V

I imagine 16V is fine as it's in the signal path, not on a power rail or anything (which are +/-24V)

Wanna make sure though. ???

 

[JohnRoberts]

It seems prudent to use 25V

JR

PS: They even spelled "bus" correctly on the schematic.  :'(

 

[volker]

Sorry to disagree... for normal operation something like 5V should be fine in my opinion. On both sides of the cap is basically "ground", so there is no DC potential across it. All it drops is AC voltage. Worst case for a 470µ at 10Hz with 600 load at 20VPk would be 1V. That's also what you find on API schematics.

The only downside I can imagine to using a lowvoltage capacitor is a blown opamp that is stuck on one of the rails. That might take the cap with it.

 

[scott2000]

but wondering if I can lower the voltage to accommodate for size issue.

Panasonic has the FS series now....

https://www.elektormagazine.com/news/new-miniature-aluminium-electrolytic-capacitors-from-panasonic

 

[JohnRoberts]

Sorry to disagree... for normal operation something like 5V should be fine in my opinion. On both sides of the cap is basically "ground", so there is no DC potential across it. All it drops is AC voltage. Worst case for a 470µ at 10Hz with 600 load at 20VPk would be 1V. That's also what you find on API schematics.

I don't spec parts for typical, I spec them for worst case...

The only downside I can imagine to using a lowvoltage capacitor is a blown opamp that is stuck on one of the rails. That might take the cap with it.

And if the DOA pegs to a rail and the under voltage cap shorts, it could damage the transformer with DC.  or not...

It is a fair gamble to use a low voltage part, just not conservative engineering.

JR

 

[scott2000]

Yeah I was at the surplus yesterday and was concerned about some small wire and it's rating. The guy looked at my schematic and said, yeah, it'll be fine...No more than so and so milliamps will go through... I said, what if something shorts or whatever.....He said, well yeah.......if something shorts..... :-\