The basic equations for how to make a capacitor seem to confirm that idea.Is there a linear relationship between the capacitance and the area? In other words, if the piece was 2' x 5 1/2", would the capacitance be 487 pF?
Two conductors divided by an insulator is the definition of a capacitor. Circuit board capacitance is an inescapable fact caused by its shape. Area and distance were provided in the first post. The only thing missing to write the complete equation for circuit board capacitance is the dielectric constant of fiberglass.Interesting.... never thought of a PCB as a substitute for a capacitor... what would be its advantage, higher voltage capability?
Yes, I understand all that, thank you. It's just that I think it's very easy to get a commercial capacitor of 975 pF (almost 1 nF), but it would probably have a voltage rating of a few hundred volts at most.Two conductors divided by an insulator is the definition of a capacitor. Circuit board capacitance is an inescapable fact caused by its shape. Area and distance were provided in the first post. The only thing missing to write the complete equation for circuit board capacitance is the dielectric constant of fiberglass.
Better than some, worse than others. For even higher voltages, try a Leyden jar.What I'm wondering is if using PCB's as caps could maybe work with much higher voltages.
Not true. I have a drawer full of 1000 pf ceramic caps rated at 1000 volts.I think it's very easy to get a commercial capacitor of 975 pF (almost 1 nF), but it would probably have a voltage rating of a few hundred volts at most.
MMMhhh.... a ceramic disk capacitor of 1,000 pF, rated at 15kV, for only $24.81 ... I'd still like to know how much voltage a makeshift PCB on could take ...Not true. I have a drawer full of 1000 pf ceramic caps rated at 1000 volts.
Here's a page of 1000 pf caps rated for 15Kv to 30Kv
http://www.mouser.com/Passive-Compo...Z1ykkklbZ1ykkklaZ1ykkkjcZ1ykkkjb&Ns=Pricing|0
Man, what a memory... the Leyden jar was my first love in electronics when I was a kid. I just loved to play with it.Better than some, worse than others. For even higher voltages, try a Leyden jar.
You can figure it out yourself.I'd still like to know how much voltage a makeshift PCB on could take ...
I think joeyd helped invent them.Man, what a memory... the Leyden jar was my first love in electronics when I was a kid. I just loved to play with it.
Question answered, thank you.
You need to use dielectric strength. The breakdown voltage is a function of board thickness.Question answered, thank you.
I still wonder about temp stability, though.
If I should only be so famous.I think joeyd helped invent them.
I very much doubt that's what you really want... you've (wisely, imho) done everything possible to protect your privacy in this placeIf I should only be so famous.
Wondering if not too prone to unpredictable variations due to changes in temperature, depending of next of what you assemble them, fans, etc. Maybe not hard to test, now that I think of it...Yes, I understand all that, thank you. It's just that I think it's very easy to get a commercial capacitor of 975 pF (almost 1 nF), but it would probably have a voltage rating of a few hundred volts at most.
What I'm wondering is if using PCB's as caps could maybe work with much higher voltages. After all, when caps fail it's mainly because their insulator breaks down due to over voltage, isn't it?
I made a few of those but most of what I played with required higher capacitance at lower voltages so I used whatever paper I could find and aluminum kitchen foil.Man, what a memory... the Leyden jar was my first love in electronics when I was a kid. I just loved to play with it.
The board might be good for 50KV, but don't forget the path around the edge of the board. That tiny air gap is not good for 50KV.Question answered, thank you.