Capacitor voltage value

[XImusic]

Hi, I'm new to the forum, glad to be here and looking forward to browsing around the forum which seems to be great! Started recently working on guitar effects... Looking at a pedal schematic for a clean boost, I found something in the schematic that with my little knowledge looks like it could be argued?
http://www.modkitsdiy.com/sites/defa...0Schematic.pdf

There is a .1uf cap right next to footswitch lug 3, which in the parts list page appears to have a max voltage of 400v. 1. Does it really need to be that high?? the voltage measurements are even specified... 2. would it ever go above 9v in a 9v powered effect? 3. are they just selling you that to make more money? (if you were to buy the kit)

Gonz

[Jazz P Bass]

Well, it is the first thing the outside world sees when something gets plugged into the input jack.
Mosfet gate protection maybe.
You never know what someone will do.

[XImusic]

Aha, good point, thanks

[XImusic]

I don't have this cap, and I might substitute it.. I have a .1uf one but it's a much lower voltage (50v) and I also have a one with greater voltage (630v) but it's also a greater capacitance of 1uf.. Is it safe to use either of these?

[Enzo]

Stick with the value. Use the low voltage part. If teh cap dies, you will know you zapped it with static electricity.

You can easily have 5000v of static charge on your body and never feel it. Grab your guitar plug and shove it in the hole and you discharge that static into the circuit. Those 15000v charges that zap your knuckles on a doorknob are what you notice, not the smaller every day charges.

I don't see the parts list. But perhaps the list is what they send out, not necessarily what the circuit needs. I stock for example a ton of 0.047uf 630v film caps. If a circuit calls for aq 400v cap, I put the 630v part in its place. Not because I have some voltage hangup, but simply because I don't see the need to stock both 630 and 400v caps of the same value. It is possible these guys got a buy on some 400v caps and they use them instead of spending more money just to get lower voltage parts.


A quick look through Mouser and in unit lots I see 400v 0.1uf film caps as low as about 36 cents. I then looked at 50v ones, and indeed I found film ones for maybe 29 cents and multilayer ceramics for 10 cents. SO I don't think they went to a 400v part to jack up the price, the cost difference is a quarter. Even lower if bought in bulk.

[XImusic]

Great, thanks! Now that makes sense to me! By the way the parts list is here
http://www.modkitsdiy.com/sites/defa...structions.pdf sorry I forgot to put it up!
Probably right about the price not making a difference!
Just going to have to be careful with that static then, thanks for the advice on that

G