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Fusion916 12th January 2013 01:13 AM

Blowing 1n4001 diodes after switching power supply on
I'm using a 350VA torioidal step down transformer with 18Vrms output and following the transformer I have a diode bridge comprised of 1n4001's. Right at power on I'm litterally blowing up the diodes (plastic casing blasts off, destorys the diode).

Is this happening due to not enough reverse recovery (50V) of the 1n4001 and can't handle the inrush current? Do I need a higher VR and higher current diode for the bridge?

nigelwright7557 12th January 2013 01:28 AM

You need to be looking at least 100v diodes with many amps rating.
I use a bridge rectifier RS 395-4332 which is 35 amp 200volts.
That's quite a high rating but they are cheap enough.

When you first apply power to the transformer the smoothing capacitors are virtually a short circuit for a while.

Fusion916 12th January 2013 04:47 AM

Ok I put in some more beefy diodes (600V reverse bias and 3A IF) and everything works fine.

Lesson learned. When working with large VA transformers use manly diodes.

TANDBERGEREN 12th January 2013 04:52 AM

1N4001 = 1Amp 50V
Not suited unless they are for some auxillary power, as for speakerprotection with an AC not greater than 35V RMS.

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