cant find the source of the charging of capacitor

[kannu789]

i have 2 capacitors connected in parallel with the a flash tube.
they are charged by the a dc power supply and even if i disconnect the power supply with a switch the capacitors keep on charging... i cant seem to find the reason.

 

[betwixt]

Electrolytic capacitors tend to do that. You are looking at residual chemical reactions in the electrolyte material. It will never fully recharge, eventually, the leakage current will overcome the battery action and the voltage will fall again.

Now you know why high value resistors are often placed across high voltage capacitors - it's to make sure they discharge quickly and lessens the effect you are seeing.


Brian

 

[pranam77]

When you disconnect the power, the electrolytics are already charged. Thus you can measure the stored potential across the same. Cheers

 

[kannu789]

but the charging goes on to about a sec. i disconnect the circuit through a switch when the capacitors have charged to about 150V. but thy keep on charging for about a sec and the potential rises to 180V. and i want to keep the voltage constant at 150V but if i apply a high resistance in its parallel it will discharge. how can i solve dis problem of overcharging without discharging the capacitor?

 

[pranam77]

When you charge eletrolytics, those will chrge up to the available potential in the main supplly connected to the same. Thus to stop chrging to 150 volts, decrease the supply voltage to 150v where the capacitor stops charging. Cheers