Capacitor Testing

How to test a capacitor using a curve tracer

While you could buy dedicated curve tracer, they are essentially just a dual channel oscilloscope, a low output impedance signal generator and some resistors along with a switch and a pot to make it convenient to use.

Electrolytic capacitors have a tendancy to run hot when used on switchmode power supplies and computer motherboards etc, this causes the electrolyte to boil and blow out the pressure relief vent (often a rubber plug on axial lead caps and a "deliberate weakness" in the metal end cap of radial lead caps) causing them to fail and damage other components on the PCB with corrosive fluids.

Often you will see a capacitor bulge showing the signs of high presssure build up, the capacitor is likely to have failed even though there is no leakage of fluid, capacitance / ESR change and leakage currents will be evident.

Category:

Education

Tags:

• Curve
• Tracer
• Current
• Voltage
• Capacitor
• ESR
• Capacitance
• electronics
• testing
• electrolytic
• electrolyte
• leakage

[jayynecobb]

Thumbs down for use of MS Comic Sans.

[eggonrunway]

@jayynecobb What I can tell you is that I 'really do' have a nice life.

[eggonrunway]

The testing signal is provided by a function generator set to produce a sine-wave at a suitable frequency for the capacitor being tested ire high value cap then lower frequency used and voltage can be anything from a few hundred mV to 20Vpp.

[powermaks]

@jayynecobb i bet you are the one that disliked that video, the only one

[AintBigAintClever]

I really should get to know my oscilloscope a little better. Saw this vid and thought it looked like a useful thing to do with one, turns out my 'scope (Hameg HM-205) has one built-in! :)

[marcvie9]

@jayynecobb well fuck you

[misium]

Great, labeled axis!

What is the testing signal ?

[djmcjo123]

Awesome music :P

[thewii552]

nice!