Electronics > Beginners
CAPACITOR Checking
Siwastaja:
Electrolytic capacitors are supposed to have quite high ESR values; it has both positive and negative effects.
Sounds a bit high, but not ridiculously excessive for such a tiny elcap. Maybe less than an order of magnitude too high. Would expect at least several ohms in any case.
Vloss is a non-standard term and may mean anything, you need to refer to the manual of your meter, if such a thing exists.
Gyro:
Interesting readings, it's a useful 'bad capacitor' test case (you might want to keep it around, carefully marked). Fundamentally though, it's unfit for service in any circuit. There's no way a good cap should get that bad in storage, even after many years.
P.S. Vloss is explained in the standard AVR based ESR meter writeup but I've never quite understood it. It's an arbitrary figure.
vinlove:
Wow, thank you for all great info. Interesting.
I was going to use the cap for the PIXIE 40m CW QRP kit radio, but it will have to be discarded, now it is confirmed as unfit for live circuit.
Will have to search through parts draws to see if I have the same value capacitance cap. :(
Jwillis:
It's not unusual for electrolytic capacitors to go bad after 2 -3 years without reforming . Its depends on the manufacturer.For example Nichicon recommends no more than 2 years at 35C before forming is required.
Storage temperature ,rate of dielectric dissolution ,electrolyte evaporation,volume of electrolyte,type of electrolyte are all factors ,but typically electrolytic capacitors should not be stored for longer than 3 years without reforming.Dielectric dissolution can almost always be reversed through reformation.
For large capacitors, reforming may be an option because of the economics involved. For small ones like yours it would be much more economical just to replace it.
As for the ESR.The smaller the rated capacitance the higher the ESR will be.For a 100uF it should be no more than 0.2 Ohms. 1uF caps can be as high as 20 Ohms.
Best approach is not to store large volumes of electrolytic caps and only purchase as needed.
vinlove:
I have searched my component draws, and found a couple of Electrolytic capacitors of the same value = 100uF, but the one gone bad is rated at 16V. The newly found ones are rated at 10V.
Both of newly found caps were near the value of 100uF. This is strange, because these newly found ones are actually a lot older from the manufacturer. They are actually almost 10-20 years old, but never been used. ESR was about 1.9 ohms.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version