500ma78/79 blow up!

[Rene Schmitz]

At 18:21 27.01.00 +0000, Ken MacBeth wrote:
>Hi, anyone got any why reason the heater elements in
>3046 prodigy expo gens blow when basic 1 amp 78/
>7912's are used as opposed to circuit specified 78m/
>79m12's (500ma)are used, I've tried many times to
>solve this problem, and when I ask, I am normally told
>that the circuits should only drag the current they
>need...

I would suspect the 78M12's internal current limiting will limit the 
current in case of a short. It can be that the heater will try to soak 
so much current when it is cold, that the 78M12 would limit the current 
to a safe size, but the 7812 would permit a higher current, thus giving 
it enough to blow up.

Bye
 René


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