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December 17, 2016 at 6:53 pm #16342MaryMemberCredits: 0
I’m new to LTSpice and at the advanced beginner level as far as actual electronic knowledge.
I am trying to turn on or turn off inductive loads of some wall warts that run from 120 volt 60Hz power. I am mainly interested in full on or full off. I know I need to have a triac that switches inductive loads. Some triac based dimmers bought from various local vendors don’t work well, creating audible noise that can be easily heard, even with my hearing impairment. I think the store bought units aren’t designed for switching inductive loads.
I wanted to investigate this further using LTSpice and the lamp dimmer circuit shown at:
However the circuit will not vary from full on (which works ok) to full off (it abruptly shuts off. As Rdim is adjusted above 320k, there is no control of the triac from ~100 degrees and 180 degrees of the input cycle. How do I get the circuit so there is adjustment range between 100 to 180 degrees of the input cycle? I’d like to get the voltage across the lamp down to ~10 or 20 volts peak, and right now, I can’t get less than ~120 volts peak.
I have tried changing the value of the timing capacitor, it makes no difference.
I also tried to probe the voltage on the gate of the triac, LTSpice won’t allow it for some reason. I can measure the triac current, but not the triac gate voltage.
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