I'll have ceramic capacitors here tomorrow or the next day that are large enough to use in this project. I have the 10nF and 100nF covered, I just don't have any 1uF ceramics right now... I do have polyester, but they're 100v and none large enough.
Hey, while I'm on this. I've read time and again that capacitor voltage doesn't matter. Just that it needs to be greater than the voltage in the circuit. If I'm running a 5v something I can use a 6.3v or 10v cap, but I can also use 1000v cap. As long as the capacitance value is right for the job, the voltage won't have any negative effects? At all? There is no advantage in this case in using 6.3, 10, or a 1000 other than cost??
Thanks, John
Sort of! It depends on the type of capacitor...
Short Answer: As long as the maximum voltage you place across the capacitor is lower than the capacitor's rating, it won't blow up or anything. The voltage rating is literally the working voltage of the capacitor. (So, like you said, you can put 5V across a 6.3, 10 or 1000V capacitor and you're fine; however you shouldn't put 1000V across a 6.3V cap!)
Long Answer: Depending on the dielectric of the capacitor, what you're using it for and the temperature you'll be using it at, you may need to derate the value.
Aluminum Electrolytic: These are generally used for bulk storage and smoothing ripple. As a rule, the higher the voltage rating of this type of cap, the larger the ripple current it can tolerate. This shouldn't be something you have to worry about unless you're making a huge linear power supply or something.
The voltage rating of AE caps is also fairly conservative; you can generally go over the rated voltage without trouble (assuming you're using a brand name cap and not a questionable off-brand). If you do exceed the voltage rating, you'll lose some capacitance (e.g., if you run a 10uF 6.3V cap at 9V, you might only get 8uF of capacitance).
Ceramic: These are generally used for decoupling. They tend to be very temperature sensitive, and quickly lose capacitance as temperature changes when run near their rated voltage. Say you've got a board inside an enclosure that gets up to ~85c. You've got a bunch of 1uF and 0.1uF 6.3V Z5V ceramic caps on the board to decouple the 5V rail. Well, because you're running them near the rated voltage and at a temperature above ambient, the capacitance could be down by as much as 80% (meaning that 1uF cap is really a 0.2uF cap)!
The way to avoid this is to use better dielectrics like X7R (which will only lose 15% of its rated capacitance over a temperature range of -55 to 125c). As a rule you should also derate the voltage, I like to make sure my ceramic caps are rated for at least double the voltage they'll see (so, a 10V cap if I'm decoupling a 5V rail); this also helps to lessen the loss of capacitance over temperature.
MLCC style caps should be avoided anywhere they'd be exposed to frequencies in the audio range. Due to the nature of their construction, they can actually resonate and "sing"! The inverse is also true, so additionally they should be avoided in equipment that will be exposed to regular vibration or shock, as this can cause the capacitor to actually generate a voltage on its own! (This is called microphonics and I believe Dave did a video on this, where he taps an SMD cap and shows the voltage on a scope.)
Tantalum: These have similar uses to AE caps. You absolutely *must* obey the voltage rating of tantalum caps! They have a nasty habit of literally exploding (violently, too) when their voltage rating is exceeded. Tantalum is also a conflict mineral, which is sort of interesting from a philosophical point of view.
Okay. So that's the long version of the basics.