6 Dec
2005
6 Dec
'05
4:25 p.m.
I take a bench power supply and a resistor and bring the caps up that way- sometimes you
have to disconnect a wire or two, but not always, and the resistor gives you a degree of
safety a straight variac wouldn't.
6 Dec
6 Dec
1:48 p.m.
At 06:25 PM 12/6/05 -0600, you wrote:
That's what I was thinking of doing. I keep a bunch of HP adjustable
voltage/ adjustable current supplies around and they've come in handy for
LOTs of different things. (I used one tonight to recharge and test some
lead-acid batteries for my HP 5315 Freq meter then used to same supply to
manually drive the VCO LO in a spectrum analyzer that I'm working on.)
Q: How high of a voltage do you use the reform the caps? I'm wondering
if it's necessary to apply full (or nearly full) rated voltage or if
they're fully reformed at say 5 VDC. Has anybody done any testing in this
area?
Joe
I take a bench power supply and a resistor and bring
the caps up that way-
sometimes you have to disconnect a wire or two, but not
always, and the
resistor gives you a degree of safety a straight variac wouldn't.
7:37 p.m.
Joe R. wrote:
Q: How high of a voltage do you use the reform the
caps? I'm wondering
if it's necessary to apply full (or nearly full) rated voltage or if
they're fully reformed at say 5 VDC. Has anybody done any testing in this
area?
I assume the vorking voltage + some safety margin.
A quick search found this link on the web of a circuit to reform the caps.
http://www.vmars.org.uk/capacitor_reforming.htm
3:02 p.m.
At 08:37 PM 12/6/05 -0700, you wrote:
Joe R. wrote:
I disagree. Caps have a definite voltage limit and in many of them it's
not much more than the stated working voltage. If you apply too high a
voltage then the insulating layer will breakdown and the cap will short.
Limiting the current will prevent the cap from exploding but I think you'll
permanetly damage the cap. I wouldn't go go above what ever the maximum
voltage is for the cap. But further, I wonder if even that much voltage is
necessary. I believe that once you apply a certain voltage the insulating
layer reforms and any higher voltage is unnecessary and possibly dangerous
to the cap.
Q: How high of a voltage do you use the reform
the caps? I'm wondering
if it's necessary to apply full (or nearly full) rated voltage or if
they're fully reformed at say 5 VDC. Has anybody done any testing in this
area?
I assume the vorking voltage + some safety margin. A quick search found this link on the web of a circuit
to reform the caps.
http://www.vmars.org.uk/capacitor_reforming.htm
Interesting circuit but it's really only good for caps that are rated
between the ignition and maximum voltages of the neon lamp. Most of the
circuits that we're interested in will be 5 or 12VDC and that too low for
the neon lamp to trigger (~60V). That's the problem with this whole
subject, there's no one approach that's going to satisfy EVERY situation.
Joe
8:32 p.m.
Joe R. wrote:
I disagree. Caps have a definite voltage limit and
in many of them it's
not much more than the stated working voltage. If you apply too high a
voltage then the insulating layer will breakdown and the cap will short.
Limiting the current will prevent the cap from exploding but I think you'll
permanetly damage the cap. I wouldn't go go above what ever the maximum
voltage is for the cap. But further, I wonder if even that much voltage is
necessary. I believe that once you apply a certain voltage the insulating
layer reforms and any higher voltage is unnecessary and possibly dangerous
to the cap.
Then use the surge voltage rating for the caps. But since I don't know
the rating of the Caps
for a S100 Buss,I am guessing about 20 volts working and say 25 volts
surge. At one time you
could find such caps now days reforming may be the only option.
6907
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6907
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