Build Your Own Arcade Controls Forum

Main => Monitor/Video Forum => Topic started by: Dave Wave on March 18, 2008, 10:42:58 pm

Title: Roll your own Cap?
Post by: Dave Wave on March 18, 2008, 10:42:58 pm

I was trying to find a 3.3uf 160v Bi-polar cap.....and they are hard to find. Can two caps be combined to form one of the value I need? How so?


Thanks,

Dave

Title: Re: Roll your own Cap?
Post by: qrz on March 18, 2008, 10:50:12 pm

two 10uF@100v caps in series will provide 5uF@200v        +                +
for non-polarized effect , tie the neg leads together          ----l[-----]l------


qrz

Title: Re: Roll your own Cap?
Post by: MonMotha on March 18, 2008, 10:53:48 pm

Yes!  The easiest way to combine them is in parallel.  That is, you wire the caps such that corresponding leads from each are connected to each other.  You'll have two "big leads" in the end where all of them are twisted together.  In this case, the resulting capacitance is the sum of them all, and the effective voltage rating is the lowest of them all.

You can also wire them in series.  In this configuration, the caps are wired such that one lead from each connects to the opposite lead of the next.  The resulting capacitance is 1/(1/C1 + 1/C2 + ... + 1/Cn) where Cn is the capacitance of each capacitor in the string.  The effective voltage rating is the sum of all of them.  In this case, the voltage ratings really need to be the same, and you may need to force equal voltage sharing using a resistor ladder in parallel with the cap string, which makes the setup slightly more complicated.

You should normally only combine capacitors of the same type (electrolytic, ceramic, mylar, etc.) unless you know you have reason to mix.

Title: Re: Roll your own Cap?
Post by: Dave Wave on March 20, 2008, 10:02:23 am

Thanks...I'll give it a go.

-Dave

Title: Re: Roll your own Cap?
Post by: shardian on March 20, 2008, 10:26:30 am

Quote from: MonMotha on March 18, 2008, 10:53:48 pm

Yes!  The easiest way to combine them is in parallel.  That is, you wire the caps such that corresponding leads from each are connected to each other.  You'll have two "big leads" in the end where all of them are twisted together.  In this case, the resulting capacitance is the sum of them all, and the effective voltage rating is the lowest of them all.

4 disposable camera flash caps+ parallel wiring = fun to throw at people you don't like. ;D

My roomate loved yelling "CATCH" and hurling them at people who walked in. They would almost always trip the firing switch.