I really hate electrolytic caps...

[zachomega]

Just finished a build only to find a scratchy volume pot.  Depending on how I have the knobs set, I have anywhere from 5 to 20 mV on the pot.  Lovely. 

I need to start throwing out electrolytics when they don't get used for a while. 

-Zach Omega

[zachomega]

OKay, perhaps somebody can elaborate on a better method to test caps, but as of now, I am instituting this system for electrolytics.

Take a 9 volt battery measuring around 9 volts.  Hook the positive end of the battery to the positive end of the cap.  Hook the negative side of the battery to the positive side of my meter.  Hook the negative side of the meter to the negative battery terminal. 

Set the meter to measure dc current in the 200uA range. 

I measured two caps this way and got .1 and .0.  Any better or different systems? 

-Zach Omega

[R.G.]

Try this. Hook a 9V source to the + end of a battery and the red lead of a 10M input impedance DMM set to volts to the - end. The black lead of the DMM goes to the voltage source negative. If the voltage reads over 0.9V, the cap is under 100M leakage resistance, and is questionable. If the voltage reads 4.5V, the cap leakage resistance is 10M and I would not trust it at all.

[birt]

if i just use the capacitance meter on my dmm. can i see if it has high leakage?

[snap]

Try this. Hook a 9V source to the + end of a battery

[zachomega]

He meant the cap not battery. 

-Zach Omega

Try this. Hook a 9V source to the + end of a battery

[zachomega]

An interesting observation I made was that the leakage current increases with temperature...Not quite as sensitive as a germanium device...more like a silicon device.  I held a cap leaking 1.5 uA of current and watched the meter slowly go up to 1.8 uA.

-Zach Omega

[Meanderthal]

 I hate em too! I try to use tants where possible to avoid them(at least they won't ooze brown slime), but I've heard folks say they don't sound good or something. Can't say I know the difference, cause if I build it and it works and I like it I leave it alone and move on...

Thanks for the tip on testing them! Since I don't trust em and I can't always avoid them I might as well at least know if they're good. For now... til they're not... heh.

[jonathan perez]

i hate mine so much, im going to eat them

[Cliff Schecht]

I hate em too! I try to use tants where possible to avoid them(at least they won't ooze brown slime), but I've heard folks say they don't sound good or something. Can't say I know the difference, cause if I build it and it works and I like it I leave it alone and move on...

Thanks for the tip on testing them! Since I don't trust em and I can't always avoid them I might as well at least know if they're good. For now... til they're not... heh.

Unless the cap in question is directly in the audio path, it really doesn't matter which type of cap you use. Of course there are different types for different reasons, but as far as effects building goes, you aren't working with ultra-hifi equipment anyways. In the audio path, I use tantalums for their lower signal-noise ratio, or if something is calling for a 1uF cap in the audio path, I'll always try to use poly. Anything under about 1000pf (.001uF) I tend to use film or silver mica if I have the part laying around, but in almost every instance a ceramic cap can be used in place with no discernable results, especially if you are down in the >100pF range.

[gez]

One solution