Noob question - polar vs. Non Polar caps?

[NBreidenbaugh]

Hello,

I am building a Vox TB clone and the schematic calls for a non-polar 0.15uf cap. The caps I received with that value are polarized. 

Can polar be subbed for non-polar, if so, how do I know which way round to hook them up? Can this be determined from the schematic? I've read too many horror stories about projectile goop, fire, general mayhem; all things I'd like to avoid on my first build if possible...

Many Thanks,
Nate

[darron]

Depends on where it is needed. You have the exploding caps when you install them backwards on power supply filtering.

If it's for a coupling capacitor then it's a simple as having the negative side of the cap go to the more 'Earthy' end. For example if there's small small voltage on one side from bias then that should be the positive side of the cap.

I'm not familiar with the circuit and am out now. Could you link to the schematic?

Just need to pull out the volt meter and see which side is higher voltage relative to Earth.


Some people don't like the sound of them in some circumstances. Sometimes electros sound better with a small
NP cap across them. But definitely should be useable.

[petemoore]

  _ Goes to the most - voltage in the circuit.
   Some positions change polarity, use bipolar electrolytic for the large uf positions like these.

[merlinb]

I am building a Vox TB clone and the schematic calls for a non-polar 0.15uf cap. The caps I received with that value are polarized. 

Are you sure they're polarized? Highly unusual to get a polarized cap that small in value...

[R.G.]

It is unusual for aluminum.

Tantalum electros are common in that value, if tantalum is ever "common" because of the oddities of tantalum. And I've never seen a bipolar/non-polar tantalum.

@ original poster:
use 0.15 film and don't sweat the polarity issues.

It may be that the guy who drew the schematic just wanted to be sure you didn't use a polarized electro at near zero voltage across it, which is a proper thing to do.

[NBreidenbaugh]

I'm not familiar with the circuit and am out now. Could you link to the schematic?

http://fuzzcentral.ssguitar.com/vox.php Basically a fuzz face with different resistor values, from what I can see.

I asked for Topmay 07 .15uf box caps, but Smallbear sent me something else: little yellow droplet-looking things. They're definitely polarized, there's a long lead and a short one, and there's a little plus on the yellow bit next to the longer lead. If that's not a Noob description, I don't know what is...

RG: I'll probably just go get a .15 film per your recommendation, and save the unidentified ones for another project.

Thanks, everyone.

[amptramp]

I asked for Topmay 07 .15uf box caps, but Smallbear sent me something else: little yellow droplet-looking things. They're definitely polarized, there's a long lead and a short one, and there's a little plus on the yellow bit next to the longer lead. If that's not a Noob description, I don't know what is...

RG: I'll probably just go get a .15 film per your recommendation, and save the unidentified ones for another project.

Thanks, everyone.

This is a perfect description of the more common varieties of tantalum electrolytic, and yes, it will be polarized.  I concur, use film capacitors and save the tantalums for some other project.

[darron]

isn't smallbear great? they stock a lot of very useful stuff, in full quantities, and decent prices. however often send you the wrong crap :s haha

if you're overseas it's worse too. i just put it aside and get something local to tide me over.

[Projectile]

Whenever I have gotten the wrong components from smallbear they were always really good about correcting the error promptly. Just send them an email and you should have the right caps in no time. You definitely do not want to use a polarized cap there.

[darron]

Whenever I have gotten the wrong components from smallbear they were always really good about correcting the error promptly. Just send them an email and you should have the right caps in no time. You definitely do not want to use a polarized cap there.

postage from small bear overseas always seems to take a while, actually, it's been a little bit faster recently so maybe i had a few slow ones in the past.

when it's something like a pot worth $1.50 that i needed it sounds really stupid to get them to send a new one at $$$ shipping and i'd still have to wait quite a long time. i'm sure they would send it free without a second thought though...

anything that gets send wrong i figure i'll use one day. it's just the delay from errors.