I've been looking at creating a simple circuit to slowly turn a halogen daylight bulb on over about 30 minutes as soon as power is supplied to simulate dawn.
I've got a 240VAC 42W halogen bulb that will be used in conjunction with a 7 day timer socket. I've been looking at various triac and triac opto driver (MOC3020) circuits to try and find one that will do this but they all want to be really fancy and use microcontrollers or other such things to do far more than I need. I just want a simple circuit that will brighten the bulb over a set time (30m) when it is turned on by the timer socket.
Help with values and component ratings would also be greatly appreciated.
Thanks for the responses. Further to this; size and heat dissapation are factors for this circuit as it will need to fit within some sort of lamp holder, also when I have looked at the triac solutions they all talk about chopping the ac waveform and doing from the zero crossing point to provide a smoother operation which made me think of the following:
Is it feasible to chop the ac waveform with a pwm at a higher frequency (5kHz)? Would this make it buzzier of lessen the buzzing or is it just totally unnecessary?