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# Question dealing with high volt capacitors in series Answered

As we all know (at least most) you can get free cameras at places that recycle disposable cameras. After having my fun hooking then in parallel to attempt coil gun, or just melting holes in water-filled soda cans. But I wanted to try to hook some in series, so instead of 320V, i got 640. I know series adds up so both are fully charged to 320V, but heres my question. 1: Can they ever blow seeing that the output is 640 yet their rated 320? 2: If i discharged between then, can i have a greater chance of them exploding comparing to parallel hooked?

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## 24 Replies

Goodhart (author)2008-03-21

I don't believe the "capacitor's voltage ratings" will be increased by putting them in series. I do know that the total "capacitance" in series will have a lower total capacitance than any single one in the circuit.

C1 * C2
-\-----------
C1 + C2= CTotal

if they are the same capacitance then it is simply

1/2 * CTotal

Goodhart (author)2008-03-21

make that 1/2 C = CTotal

tech-king (author)2008-03-21

i was wondering what was up with your equation

Goodhart (author)2008-03-21

That second one I seemed to have dropped something (a token ring maybe, and it rolled under the desk, no less LOL).

I wasn't aware that the voltage ratings increased when putting caps in series, I did know the capactance decreased in series. Oh well, I have to get my books out again and brush up on that stuff :-)

Now where did I put those manuals: Ah here's one.

And my Raytheon Manual
:-)

tech-king (author)2008-03-22

thanks for posting pdfs. i saved the first one, and will read it later.

Goodhart (author)2008-03-22

They are a bit "old" :-) Not that the information is "outdated" but it may be hard to find some of the "parts" i.e. Tubes - LOL

tech-king (author)2008-03-22

thats why i saved the first one only

Goodhart (author)2008-03-22

I actually do have a few tube manuals around the house here. And a LOT of, so called out dated parts (IC's, etc) Data books, etc. They were useful at one time, now I don't run into those parts as much anymore *sigh*

tech-king (author)2008-03-21

cap Vratings are increased. its the principal on which the MMC is based. and you need several in series to get a high enough rating for tesla coils.

gmoon (author)2008-03-21

Yep. You'll double the working voltage rating if you connect two identical caps in series. No need to charge them separately. And halve the capacitance, as goodhart noted.

Goodhart (author)2008-03-21

And halve the capacitance, as goodhart noted.

unless one is lower than the other in farads.

tech-king (author)2008-03-22

of course, if you put several in series, it becomes even more complex because the value is calculated by:
Ctotal=1/(1/c1)+(1/c2)+(1/c3) and so on. break out the calculator right about now.

Killa-X (author)2008-03-21

Well if i hook them in series like ---O---O--- my multimeter reads 580 (didn't full charge) when the caps say 320V photoflash

guyfrom7up (author)2008-03-21

if you carge them each seperatley, each to 320 volts, and then hook them in series and then discharge it everything would be fine. Having 2 discharged ones in series would make it be able to handle 2x higher volts (640), but it will only have half the capactance (if it's 100uF each, and then put them in series the capatance will be 50uF)

guyfrom7up (author)2008-03-21

oh, and for almost any project I consider putting caps in series a waste, it takes up almost 2x the space than it has to.

westfw (author)2008-03-22

Since you're talking about FREE caps, consider that mixing them in assorted series/parallel combinations will give you new (FREE!) values of caps that you might otherwise have to PAY FOR. For instance, when converting a flash to a repeating strobe, you usually want a lower capacitance to increase the repeat rate. You can get such a lower capacitance by connecting several of the nomal caps in series (just cause the series combo supports a higher voltage doesn't mean you HAVE to charge them to higher voltage.) Yeah, it's bulkier than it needs to be. But it's still FREE!

Goodhart (author)2008-03-21

especially at these voltages. At much lower volts, you could zigzag them but it still wastes some space

Killa-X (author)2008-03-21

All I want to know, is if i discharged across the + and - of the caps, if the 640V could blow the 2 320V caps. Since i discharge single 320V caps from the circuit a ton of times, and never had it blow, since it's rare

Goodhart (author)2008-03-21

If you are going to apply 640 v to a 320v capacitor(s), as far as I know, there is a good possibility.

tech-king (author)2008-03-21

yeah. stay 10% below max power for safety

Killa-X (author)2008-03-21

It's a flash cam circuit for the charger. so it charges full 320/320 by it self.

Kiteman (author)2008-03-21

To increase the available charge, you should wire capacitors in parallel.

The voltage across the caps will remain the same as the voltage of the supply you are using to charge the capacitors, but the total charge stored will be greater, meaning more oomph for your gun.

Killa-X (author)2008-03-21

The gun was an example ;) I'm using it more to random shock stuff and compare spark sizes. But I'll come to coilgun after i move from 1 inch camera capacitors to 5 inch 450V monsters. Thanks for your help though! always answer my questions o.O

Goodhart (author)2008-03-21

The voltage rating tells you how much voltage the dielectric (insulator) can withstand before allowing DC to pass between its plates; in a diode, this is known as the breakdown voltage. This does NOT tell you how much voltage it will have when connected to your system. If both a 16v and a 20v capacitor are connected to a system (with a voltage of 14.4 volts for instance), both the 16v capacitor AND the 20v capacitor will have exactly 14.4 volts (once fully charged). The voltage on the capacitor will be the same as the circuit to which it's connected.