hollidayp1
- Nov 22, 2013
- 6
- Joined
- Nov 22, 2013
- Messages
- 6
I have several Photoelectric Switches that work well with incandescent lamps (up to 300 watts) but they don't work with LED Lamps. Actually, one of them works with the LED lamps but 10 others do not. The LED lamps are multi-LED lamps with a standard screw base (USA) and range from 1 watt with 19 LEDs, 2 watt with 37 LEDs, and 3 watt with 43 LEDs. A schematic of the Switch is attached.
I'm not 100% sure how this circuit works but here's what I think. It looks like the triac is turned on by the 120k resistor in series with the diac (or diode?) which would basically turn on the lamp (or load) always (like in the dark or light). But then, the .047uf cap in series with the LDR (CDS Cell) would short out the T1 terminal to the gate causing it to turn off in the light when the LDR goes to a low resistance (say 3k ohms). In the dark (low light) the LDR goes to a high resistance (say 300k) and the "short" would be removed allowing the gate to be turned on by the 120k resistor and diac.
I'm not too confident in this analysis because I am not comfortable with the idea of "shorting out" the triac to allow it to turn on. Is this a common trick?
In any case, my objective is to modify these switches so that they work with LED lamps and other non-incandescent (non-resistive) loads. Before I can do that (if possible) I need to be sure about how this circuit works. Thanks for your help. 131122-2
I'm not 100% sure how this circuit works but here's what I think. It looks like the triac is turned on by the 120k resistor in series with the diac (or diode?) which would basically turn on the lamp (or load) always (like in the dark or light). But then, the .047uf cap in series with the LDR (CDS Cell) would short out the T1 terminal to the gate causing it to turn off in the light when the LDR goes to a low resistance (say 3k ohms). In the dark (low light) the LDR goes to a high resistance (say 300k) and the "short" would be removed allowing the gate to be turned on by the 120k resistor and diac.
I'm not too confident in this analysis because I am not comfortable with the idea of "shorting out" the triac to allow it to turn on. Is this a common trick?
In any case, my objective is to modify these switches so that they work with LED lamps and other non-incandescent (non-resistive) loads. Before I can do that (if possible) I need to be sure about how this circuit works. Thanks for your help. 131122-2
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