At 11:05 PM 2/18/02 +0000, you wrote:
>The circuit below uses no voltage-dropping, power-wasting TRIAC, no
>likewise bridge rectifier, no relay^H^H^H^H^H "electromechanical logic",
>and allows you to control your lamps either ON/OFF with a logic level
>from a PIC (might want to boost that up to a little higher than 5V,
>unless you use logic level FETs), or control lamp brightness with the
>PIC's PWM.
>
>            0--------------------------0
>
>         FROM 12V                  TO LAMP
>         XFORMER                    STRING
>
>            0------+           +-------0
>                   |           |
>                   |           |
>                   |           |
>                   |           |
>                   D           D
>               Q1    G---+---G    Q2
>              Nch  S     |     S  Nch
>                   |     |     |
>  GATE DRV  0------------+     |
>                   |           |
>                   |           |
>  PIC GND   0------+-----------+
>
>Voila...

Very nice, Dave! A couple of IRLZ544's maybe. They would have
a total drop of about 1.1V at 20A, so about as good as a triac.
At 10A, they'd beat it by a mile.

You should be able to get half-wave power using a diode from the
top transformer wire to a PIC-GND referenced supply.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com
9/11 United we Stand

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