Hi ALL; my circuit works fine as a dimmer. Question:
Can the load be a bridge rectifier so as to control the rectified and filtered DC?
Yes... but... The filtering and load will determine the DC voltage. i.e. With no load the capacitor will tend to charge-up to the full-voltage and stay there, particularly if the TRIAC is triggered within the 1st 90 degrees.
And, I assume you know the peak of sine wave is about 1.4 times the RMS.
Realistically, it's better to use PWM (and a MOSFET instead of a TRIAC) with DC. And, with PWM you don't have to sync to the power line so everything gets a LOT easier.
Agreed. In theory - could, in practice - not a good idea. Rectify your AC signal and then dim the DC power.
However PWM does not work for all applications so it depends on what you connect to your DC load (trying to lower the voltage with your TRIAC before rectifying likely won't work either for those applications). You can't use PWM on brushless pumps and certain LED modules (those that come with constant current driver rather than current limiting resistors).
Thanks for your answers.
it's better to use PWM (and a MOSFET instead of a TRIAC) with DC.
What I really want to do now is a home brewed low voltage power supply for led lighting.
So, half wave rectify AC line ( wont use a transformer ), filter use PWM to lower voltage
and maybe a VR, which should be viable.
[quote certain LED modules (those that come with constant current driver rather than current limiting resistors).][/quote]
I ll be using discrete LEDs; will give your advice a try and let you know. Thanks.