voltage and electrolytic caps

K

kweefthief

Active member
Hey everyone. I am new to all this and trying to sort out my cart on tayda for 6 pedalpcb pcbs. Since its my first order, there's a lot im lost about. For OD pedals, how do i make my pedals able to run on 12v/18v if that is possible. Is it better to get higher voltage electrolytic caps (50v) or are those too big? For film box caps are the 100v ones ok?
 
So the voltage rating determines how many volts the components are able to withstand. I believe the general rule is you want at least double the rating of your components to what your running your circuit at. So to answer your question yes the 100v mylar caps and 50v el caps are more than enough.
 
The higher the voltage rating of a cap, the larger it is in physical size usually. So there's no harm to the circuit if you have a large voltage rating, but you may not be able to fit it onto the PCB. Electrolytics especially can get pretty big at higher voltage ratings, so I would shoot for 25-30V, which will allow you to run at 18V, but not be too big. Keep in mind as well that all parts need to be able to handle 18V, not just the caps.
 
Certain transistors and ICs may also have maximum voltages, and also most circuits that already have a charge pump in them don’t like more than 9 or12 v—it’s worth looking at those spec also. I’ll generally see what the manufacturer of what ever I’m building has given as the maximum voltage, and gone with that.
 
Not to make it way too complicated but you might also want to pay attention to the measurements if you are using bigger caps. I typically use 16v for my 100u+ caps unless it’s one where I need more. But some 25v caps are bigger than others or you might see one that’s sort of short and squatty vs taller and thinner. Annoying that this stuff can matter but depending on the layout it can. I find it easier to use 16v electro’s unless I need to use the bigger ones myself. Smaller than 100u just get the larger voltage they stay small enough if you stay under 50v
 
Locrian99 said:
Some 25v caps are bigger than others
Click to expand...
Some 25V caps' mothers are bigger than other 25V caps' mothers

For larger electros I use 25V whenever possible but I have some 35V that are the same size. Tantalums are always smaller.
Checking the physical size is really important for film caps as well as they can get thick.
 
I have trouble with caps as I have a large head. I almost always have to get the biggest size cap in the range. Once when I was in rural California on my way with family to Yosemite we stopped in a town called Oakdale because I saw a store called Oakdale feed and seed and Western Wear. I thought I'm gonna get myself a cowboy hat. Out of thousands of white cowboy hats in the store they had three which fit me!

I would never fit on one of Mr PCB's PCBs.
 
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