Hi, Earlier, I've managed controlling simple relays over the parallel port, but now I want to be able to dim the output as well (parallel port leading to AC outlet) so I can use my par-cans with my compuyter instead of expensice DMX dimmer-racks. Does anyone know what I need to do this? I think maybe triacs may be the answer, but I'm not sure. Looking forward to answers, Plasma
If TRIACs work simply as an AC transistor, you might be able to PWM the AC if you use a frequency over 120 hz, it might work not sure though. If it does, than it would be as simple as using the parallel port to send pulses to a digi-pot controlling a PWM circuit. Though I haven't tinkered with AC that much though, so it might not work. Plus that would introduce a lot of noise into the circuit.
A triac driver opto-isolator (e.g. TLP3041) connected to a TRIAC should allow you to control the brightness of your lamps using PWM. This is something I'm looking into myself, but can't test until I'm home for christmas. I expect if you don't use a PWM frequency at least double 50/60Hz, you'll get some funny dimming effects, so keep it in the kHz range.
