Timeline for What does a reverse phase dimmer circuit look like?
Current License: CC BY-SA 3.0
17 events
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| Jan 9, 2018 at 18:06 | vote | accept | Thomas | ||
| Oct 12, 2016 at 19:00 | comment | added | Decapod | I have to look for it but somewhere I have a schematic for a zero cross detector build with standard parts. It gives a pulse at zero crossing. It is directly fed from the mains and made safe with an optocoupler. If you need just ask. Also if you are happy with my answer please accept. | |
| Oct 11, 2016 at 16:49 | comment | added | Thomas | @Decapod I've found a source article for your new diagram that includes quite a bit of useful information about the circuit itself and what each component does. eeweb.com/blog/extreme_circuits/dimmer-with-a-mosfet The article doesn't explain the purpose of the relays - K1 I think I understand, but K2 and K3 seem superfluous to me. This also doesn't describe in any way how to accomplish zero cross detection, which is one of my main points of ignorance. I think I can use the aforementioned LM741 to do it, but then I lose the isolation that Transistor correctly emphasizes. | |
| Oct 11, 2016 at 1:52 | history | edited | Decapod | CC BY-SA 3.0 |
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| Oct 11, 2016 at 1:43 | comment | added | Transistor | @Thomas: "I believe that I can connect a PWM output on the PADI directly to the gate on a MOSFET ..." Be very careful with your beliefs. Isolate if at all possible as shown in the Elektor schematic. It prevents you getting high voltages on your micro and makes debugging much simpler. You should ensure good separation between the control and mains PCBs and keep wiring segregated. Observe minimum creepage distance rules around the opto-isolator. | |
| Oct 11, 2016 at 1:40 | comment | added | Transistor | @Decapod: That's better and safer. You should credit Elektor magazine with that schematic. It is immediately recognisable as their house style. | |
| Oct 11, 2016 at 1:37 | comment | added | Decapod | @Transistor: The drawing was not mine. I have changed it. | |
| Oct 11, 2016 at 1:36 | history | edited | Decapod | CC BY-SA 3.0 |
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| Oct 11, 2016 at 1:25 | history | edited | Decapod | CC BY-SA 3.0 |
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| Oct 11, 2016 at 1:15 | history | edited | Decapod | CC BY-SA 3.0 |
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| Oct 10, 2016 at 22:38 | comment | added | Thomas | I've added a paragraph of some additional insights into my project. Based on your answer, I think the place where I need to focus my efforts is on the zero-cross detection. I believe that I can connect a PWM output on the PADI directly to the gate on a MOSFET and call the switch good. But making a zero-crossing circuit and connecting that to the PADI is where things get fuzzy. I found an article online that uses a 741 op amp for zero-cross detection. Maybe the PADI is sophisticated enough to take an unrectified v-in and I can do detection in firmware? At least this gives me a start. | |
| Oct 10, 2016 at 20:39 | comment | added | Transistor | I think you need to remove the earth symbol on the right (bridge rectifier short-circuit) and remove the link between R3 and the earth on the left (you don't need it when you have the opto-isolator). See here for explanation of the rectifier problem. | |
| Oct 10, 2016 at 19:40 | history | edited | Decapod | CC BY-SA 3.0 |
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| Oct 10, 2016 at 17:51 | history | edited | Decapod | CC BY-SA 3.0 |
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| Oct 10, 2016 at 17:43 | history | edited | Decapod | CC BY-SA 3.0 |
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| Oct 10, 2016 at 17:37 | history | edited | Decapod | CC BY-SA 3.0 |
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| Oct 10, 2016 at 17:31 | history | answered | Decapod | CC BY-SA 3.0 |