# information about bridge rectifier

Discussion in 'Electronic Basics' started by [email protected], Jul 3, 2008.

1. ### Guest

hi thanks for ur kind informaation which u have given,but i want to
know a small detail about bridge rectifier.
DOES THIS BRIDGE RECTIFIER CAN BE CONNECTED TO THE 230VAC/50HZ
SUPPLY ,WITH OUT TRANSFORMER. DOES IT WITH STAND THAT VOLTAGE OR IT
HAS TO ISOLATED.IF IT HAS ISOLATE YELL ME THE ALTERNATE METHOD TO
ISOLATE WITH OUT TRANSFORMER. KINDLY SOLVE THIS PROBLEM

THANK U

2. ### ian fieldGuest

The best way is to find the data sheet and look up the PIV rating.

The bodgers method is to connect the rectifier to the mains with a 40W lamp
in series with one of the AC terminals to limit the current if the rectifier
goes S/C.

Of course this does not guarantee that the rectifier will withstand mains
voltage in the long term - you need to have a safety margin. If you put 2
capacitors in series across the + & - terminals with the junction to one of
the AC terminals, this forms a voltage doubler.

A better plan yet is to use a resistor to limit current instead of the lamp
(33k/2W for 110V or 2x 33k/2W for 230V) this should limit the current to the
point that if the PIV is exceeded, the rectifier's leakage current will halt
the voltage rise - which you can then measure.

3. ### neon

1,325
0
Oct 21, 2006
forget about the lamp that is just current limit protection it has nothing to do with what you need to know. for 240 ac the voltage translates to 352v per diode. but if one fail then both fails guaranty solution 705 v diode or basicaly800 volts reverse breakdown to be sure. now here comes the current your load current must be what the diode can continiously substain not the inrush specification. a lamp in series is a lame idea it just non lineary limit the current saves nothing. add a fuse slowblow of the proper voltage and current rating and now get to work.

4. ### EeyoreGuest

Or Vrrm as they tend to call it these days.

Graham

5. ### ian fieldGuest

Damn these new fangled contraptions!

6. ### EeyoreGuest

Whyy DID they change it ? IEC probably.

AND don't forget to allow an extra say 50% on top for transients.

Graham

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