I hope that this question has not been asked earlier and is wasting anyones time. I don't particularly remember my ECE101 classes that well - and seek your help!
I own my grandfather's hifi amplifier that has power light indicator that recently burnt out. The bulb is proving too hard to find right now. It was a tiny filament bulb and was powered by a 8V AC current (Schematic says bulb rated 8V 40mA).
I just wanted to check if my math is still alright here.
AC 8V RMS = 8V x Square Root of 2 = 11.3V for the DC LED.
So by using a 6V 30mA led I would take 11.3v - 6V = 5.3V extra current across the circuit.
Then I would then just use V = I x R; so 5.3V/30mA = 176 ohms resistance.
By adding the 6V 30mA LED with a 180 ohm resistor would be a workable solution?
I was also told I may need a rectifier diode and a capacitor to keep a smooth glow? Are either mandatory or just optional?
Finally can I use a full wave rectifier to avoid using the cap? Any idea on how to wire this. Sorry for my basic question but every bit of help would be useful!
Thanks in advance :)