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Old 05-17-2012, 01:40 PM
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N2IXK N2IXK is offline
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Quote:
Originally Posted by Magnavox300 View Post
Thanks for the clarification!
Also, am I right in getting a 100uf and a 50uf?
Looks like they put the microfarads next to the proper combination, right?
Yes, a 100uF and a 50uF should be fine, as that is the largest set of values listed. Most likely, those are the actual ratings of your can.

Your old can was actually a replacement, and was marketed as being able to replace several ratings of caps, as increasing the capacity somewhat is generally not a problem in power supply filters. A 100/50 could safely replace all those combinations shown (and probably a few others). Just make to get new caps with an equal or greater VOLTAGE rating. The voltage rating on yours isn't visible in the photo.

Quote:
Originally Posted by snelson903
while we are on the subject of caps. here's a question i have never really been sure of, when you take a cap. wired in a parallel the lets say 22 mfd 450 v with another that is equil in value, it becomes 44 mfd what then is the voltage rating become together is it now 900 v or 225 v or remain 450 v. could it now be used in a circuit requiring a 800 volt 44 mfd cap ,or stay at 450 v making it a 44 mfd 450 cap. or what is the voltage rating become of two caps in a serise 22 mfd + 22mfd = 11 mfd does the total voltage together drop along with mfd value , or increase because there are two in a series . this is why i have never used caps. in this way unless the voltage needs were way below any concern.
For capacitors in parallel, the capacitance ADDS, but the voltage rating will remain the same as the lowest rated unit. 2 22uf/450V caps in parallel form a 44uf 450V capacitor.

For capacitors in SERIES, the capacitance DIVIDES, and the voltage rating ADDS. 2 22uf 450V caps in series effectively become an 11uf 900V capacitor. When series capacitors are of different values, the math gets a little trickier, because voltages may not divide equally across the string. Resistors in parallel with each cap are recommended when using them in series to ensure proper voltage division.
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