Re: Power Supply Circuit

Mariss -

Sounds excellent.

Presumably this circuit will work equally well with the 50Hz mains
frequency this side o' the pond?

Regards,
Tony

P.S. While I remember it - what progress with the G297 (or was it G298)?


At 03:50 15/06/2002 +0000, you wrote:

>What it does is sense the 120Hz cap charge restoring current pulses.
>If these are absent, such as when the AC power is shut off or if the
>cap is being backdriven by a drive, a power MOSFET crowbars a wire-
>wound power resistor across the supply. The resistor is sized so that
>it draws the full current rating of the supply thru it.
>
>A 10A, 80VDC supply filter cap would be 10,000uF for a 10% ripple at
>max current. The crowbar resistor would be 8 Ohms, forming a time
>constant of 80 milli-seconds. Three time constants would be about a
>1/4 second discharge time for the supply after AC power shut-off.
>
>A backdriven supply develops a voltage rise on its filter cap. This
>biases the bridge rectifier off and no current flows thru it. The
>sense circuit again places an 8 Ohm load across the supply until
>rectifier current is re-established.