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
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.
Or Vrrm as they tend to call it these days.
Graham
Damn these new fangled contraptions!
Whyy DID they change it ? IEC probably.
AND don't forget to allow an extra say 50% on top for transients.
Graham
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.