Hello George,

> I made a reverse dimmer in about 1987 using an irfp450 and a 555. The
> curcuit had bult in current limit so you could short the output and it
just
> shut off until you removed it. Later I used it without the dimmer to limit
> the inrush current in lamps for traffic lights, to improve the life.
>     I was a very simple curcuit, just semse the drop across the fet with a
> small bipolar transistor wich then shunted the gate to ground.
>You set a limit to the current that the fet will conduct - then switch it
>off. As the fet is on or off the dissipation is low.

    have you actually seen the circuit proposed by dave?

    The high current protection you are proposing (saddly) will not work
work in this circuit but only on DC ones.

    I've been thinking of a pair of very small resistances between the
MOSFETs sources and the ground, but this will reduce the circuit efficience
and a lot of power will have to be dissipated on the resistors.

    Best regards,

    Brusque

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Edson Brusque                 C.I.Tronics Lighting Designers Ltda
Researcher and Developer               Blumenau  -  SC  -  Brazil
Say NO to HTML mail                          www.citronics.com.br
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