I am attempting to build this simple peak voltage adaptor circuit. I have a IN4004 diode, a 400v x 22mf capacitor and a 1Mohm resistor. Is it essential to connect it to a multimeter to make it not blow the capacitor when connecting it to 240v ac mains. The capacitor blew on 2 occasions when I switched on the mains.

 

22mF? Do you mean 22uF (22 microfarads) or is it really 22mF (22,000 microfarads)?

[Edit] And are you sure that the diode and capacitor were connected with the correct polarity?

 

A 1N4004 does not have adequate voltage rating to use as a half-wave rectifier for 240 VAC with a capacitive filter. The diode will be subject to about 670 V in reverse (approx 2.8 times nominal RMS AC voltage, assuming a sine wave).

 

22mF? Do you mean 22uF (22 microfarads) or is it really 22mF (22,000 microfarads)?

[Edit] And are you sure that the diode and capacitor were connected with the correct polarity?

I just looked at it now and on the side it has 22uF

 

on the cathode (ie the silver line) side i put the +ve end of the capacitor

 

I just looked at it now and on the side it has 22uF

That's OK. The surge current for 22mF would be large.

As ebp says, the 1N4004 will be struggling in this circuit. Use 1N4007 instead.

 

on the cathode (ie the silver line) side i put the +ve end of the capacitor

Correct

 

thanks i really do appreciate the reassurance and forum help as i am a novice with this.

 

thanks ebp, i will try a IN4007

 

No mains isolation.
Contravenes T&C's
Thread Closed.
MOD.

User Agreement:
http://www.allaboutcircuits.com/user-agreement/

 

After a MOD discussion, it was decided to reopen this Thread.