Hey guys,

I've had two weeks of my summer holiday, and I'm already bored stiff. So i have decided to make a few pedals to occupy my time. I've built a few BYOC kits before, and thought that now was the time to start building pedals from scratch.

My main problem at the moment is finding the right parts. In this particular situation its Capacitors. I need a 100uf Aluminium Electrolytic cap. However, i don't know which wattage to get. The pedal I'm building is the Green Ringer octave pedal, as i thought starting easy and working my way up would be a bit "safer".

So my question is, could someone explain to me the theory behind solving the problem, so when i have this problem next time, i can easily work it out?

My first thought was that it would be 9v, as that is how much will be going through the pedal. I couldn't find any that were exactly 9volts, so would be okay to go higher?

Many thanks, Joe

██████████████
Last edited by Rum Monkey at Jul 9, 2008,
You actually want to get higher so that if you plug more than, say, 10v into it, the cap won't explode.

There's really no 'theory' behind it, just get a voltage rating that's higher than you need.

BTW, caps are rated for volts, not watts, and the min value is 10v.
the thing about that, is, the voltage rating pretty much determines the size of the cap. Using a 600V cap would be stupid, because it'd likely be pretty huge.
Right, so a 25V Cap would be more than adequate? Also, are Polypropylene Caps better than film Caps?

Oh, and whilst i think about it, when making PCB boards, would a permanent marker be good enough to resist the acid? Or should i use a proper etch resistant pen?

Thanks very much for your help guys, its greatly appreciated!

██████████████
The 25V cap would work.

A Sharpie will work, but you need to layer it copiously.
There's an iron-on method that uses photo paper, but it still requires a laser printer.
Cheers for that.

Just out of curiosity, you wouldn't know anywhere that would stock 2N5088/2N5089 Transistors would you? I've gone through about 10 pages on Google - but to no avail

██████████████
Try smallbearelec.com (ships worldwide) or mouser (idk). Banzai Effects is in the UK, isn't it?

Anyway, about any cap material will work, but you don't want ceramic caps in the signal path; they sound harsh and are noisy. Most people use polyester film, polypropylene, or metal film for the non-polarized (NP) caps.
Quote by Invader Jim
You actually want to get higher so that if you plug more than, say, 10v into it, the cap won't explode.

There's really no 'theory' behind it, just get a voltage rating that's higher than you need.

BTW, caps are rated for volts, not watts, and the min value is 10v.

Computers and many other electronics use 6.3V. I am sure there is smaller.

Anyways use caps that are at least 16V. If you using a power supply they may be advertised to be 9V but most are putting out 11V - 13V (under load). They aint regulated...
Shove me out to see
The sea
The quiet of December
To the deep I turn

Quote by Invader Jim
Try smallbearelec.com (ships worldwide) or mouser (idk). Banzai Effects is in the UK, isn't it?

Anyway, about any cap material will work, but you don't want ceramic caps in the signal path; they sound harsh and are noisy. Most people use polyester film, polypropylene, or metal film for the non-polarized (NP) caps.

Not necessarily...

In some of my builds and designs I only use ceramic discs... Ya they may be a bit nosier (hardly audible) but they give this great gritty, raw sound. Its all preference.

Your coupling caps are where you are really going to here the difference between caps.

I have a big box of vintage ceramics..I am always trying them out here and there. Try thjem you might like em.
Shove me out to see
The sea
The quiet of December
To the deep I turn