04-10-2013, 06:26 AM
I completely concur with the sentiments above - this is a dangerous circuit and not fit for purpose.
If you want to check the leakage of a capacitor, charge it with a bench DC supply through a current limiting resistor, disconnect it from the supply and then use a VOM, DVM or other high-input-impedance voltmeter (i.e. NOT and AVO!) to measure and plot its decay.
It'll be pretty obvious very quickly what the leakage is like and whether its acceptable. All caps leak to some extent anyway...
The picture below is an example of the curve expected from a good electrolytic - I plotted this back in 2010 from an 8 y/o extremely low ESR cap used in commercial UPS systems - a day and a half later, the voltage had dropped by 20%... (we swap these caps out every 3 to 5 years as a matter of standard maintenance - they are GBP 90 each and a typical mid-range UPS will have maybe 60 of them...).
If you want to check the leakage of a capacitor, charge it with a bench DC supply through a current limiting resistor, disconnect it from the supply and then use a VOM, DVM or other high-input-impedance voltmeter (i.e. NOT and AVO!) to measure and plot its decay.
It'll be pretty obvious very quickly what the leakage is like and whether its acceptable. All caps leak to some extent anyway...
The picture below is an example of the curve expected from a good electrolytic - I plotted this back in 2010 from an 8 y/o extremely low ESR cap used in commercial UPS systems - a day and a half later, the voltage had dropped by 20%... (we swap these caps out every 3 to 5 years as a matter of standard maintenance - they are GBP 90 each and a typical mid-range UPS will have maybe 60 of them...).
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