Re: A Bridge Replacement A Good Idea?

Pooh Bear wrote: 
John Popelish wrote:


Ron Hubbard wrote:

I found the following strobe project at:
http://sound.westhost.com/project65.htm
but I wasn't thrilled with the big diodes the circuit calls for. Rather than
buying four  stud diodes, I decided to replace them with a single 4A, 1000V bridge
rectifier. Does anyone see a problem with this?


No.  With a 1 amp line fuse, the 1N4007 diodes the author recommends
against, would do fine.  I wouldn't go over a 2 amp fuse with your
rectifier.  Are you heat sinking it?


Ahem ! Are 1N4007s going to stand up to the 32A peak charging current ?

Since there is a 10 ohm resistor in series, in addition to the fuse, the surge won't be that big. I think the 30 amp half cycle surge rating of the diodes will handle the surge batter than the 1 amp fuse will.

http://www.fairchildsemi.com/ds/1N/1N4007.pdf

A 4A bridge is very sensible.

You don't *seriously* think a normal 1A mains fuse will 'protect' 1A semis do you ? The
semis have to be rated according to the application.

A bridge or doubler built with 1 amp diodes will provide almost 2 amps of average line current (each diode seeing 2 amps half the time), and that will blow the 1 amp fuse if you get that far. I wouldn't expect to get this full rated current out of the 1 amp devices, but the 1 amp fuse will prevent it, anyway and so will the 5 watt 10 ohm resistor (40 watts dissipation at 2 amperes RMS which is well below the almost 2 amps average the diodes could take).

It is *seriously* your turn.  :-)
.

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