another capacitor question

[banjoze]

I was looking thru an assortment of capacitors that I have left over from a class I took a while back. While trying to identify their capacitance / voltage rating I ran across this tool: (http://www.electronics2000.co.uk/cal...calculator.php).

I have a couple of questions, one general and one specific.

1. How do you tell the voltage rating for a given capacitor if it isn't printed on it? The tool doesn't provide this from what I can tell.

2. How do you know if a particular capacitor is one that you can use the calculator above to decipher? For example, I have a black chiclet looking capacitor (silver mica?) that has 250 printed on it. According to the calculator it is 25pf, but I'm pretty sure we were told in the class that it was 250pf.. So, now I'm wondering if I can actually trust the calculator to give the right value or if I shouldn't be using it for particular types of caps...???

Thanks (and sorry for such basic questions),
-Gerald

[TweeDLX]

Originally Posted by banjoze

I was looking thru an assortment of capacitors that I have left over from a class I took a while back. While trying to identify their capacitance / voltage rating I ran across this tool: (http://www.electronics2000.co.uk/cal...calculator.php).

I have a couple of questions, one general and one specific.

1. How do you tell the voltage rating for a given capacitor if it isn't printed on it? The tool doesn't provide this from what I can tell.

2. How do you know if a particular capacitor is one that you can use the calculator above to decipher? For example, I have a black chiclet looking capacitor (silver mica?) that has 250 printed on it. According to the calculator it is 25pf, but I'm pretty sure we were told in the class that it was 250pf.. So, now I'm wondering if I can actually trust the calculator to give the right value or if I shouldn't be using it for particular types of caps...???

Thanks (and sorry for such basic questions),
-Gerald

The best way to determine capacitance is by using a DMM to measure it.

Mike

[SatelliteAmps]

If there is no voltage rating on it, it is pretty much impossible to tell by looking at it what the voltage rating is.

According to the three number code, a cap marked 250 with nothing else, is a 25pf. 251 would be a 250pf.