Spark in trafo output

[caringin]

Hi,

I need help using trafo. I use trafo 1 A, 18 V. After I unplug the cable from 220 V AC, there is still DC voltage output from the rectifier section. I must short circuit the capacitor to empty the capactior. Do you know why? It is very dangerous, I guess, you know the result when you short circuit 18 V DC, the spark. I use 1000uF 25V capacitor and diode bridge. How to fix it? What part should I substitute?

 

[IanP]

It is pretty normal that the smooting capacitor retains some charge for some time after AC is switched off ..
If you would like to discharge it connect a resistor of, say, 10kΩ to 100kΩ, or whatever you need, in parallel with the cap, and after a couple of seconds the charge will be gone ..

Regards,
IanP