How do I figure capacitor I need.

[waggs098]

I have a little Hitachi SR 303 receiver I put led's in for lighting. When playing at mid to high volume they dim pretty badly. I put in a full wave rectifier and have 5.4 volts supply. I'm powering 10 - 20mA led's in a series - parallel circuit. I know I'd need 6 volts or above for a cap but how do I figure the microfarads?

Thanks
Justin

 

[elnaldo]

http://www.electro-tech-online.com/...te-the-value-of-a-smoothing-capacitor.106374/

here is a very simplified calculation, it says you need 0.2 Farad for 1A load at 50 Hz and full wave rectifier.

You can adapt the formula to 60Hz (shorter time) and half wave rectifier (twice the time) and the little current the leds take.
Or just try some 220 or 470uf cap.