Hi guys,
    I'm having a bit of a problem driving a triac from a pic.
The electrical main is 220Vac 50Hz.
I have the Vdd of the pic connected to the live and Vss is 5v less than
live.
I have a PNP transistor: emitter to live, collector to triac trigger,base
via resistor (1k) to the pic i/o pin. The base is also connected to the live
via 10k resistor (to prevent false trigger at powerup).

My theory is that with the pic i/o pin high the transistor is off and
therfore high z to the trigger so no leakage current can trigger it.Thus the
triac doesn't conduct.
With the pic i/o pin low the transistor is switched on and the trigger gets
all the current it needs and the Triac conducts.

The triac I'm using is a BTA12 from Philips (logic level driven device).

My target use is for a small motor but I'm using a lightbulb for testing.

The Problem: The bulb is always on!

I thought I had all the bases covered but obviously I'm missing something.

Has anyone got an idea what this 'something' is.

Thanks in advance
John

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