| Electronics > Beginners |
| 120VAC TRIAC Dimmer |
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| soldar:
--- Quote from: vidarr on September 20, 2019, 05:13:05 pm ---Maybe someone has a link to a schematic they Know is working? --- End quote --- The schematic is good. It is pretty much the same found everywhere with minor variations. I would recommend you understand how it works so you can troubleshoot it. There have been many threads on the same circuit with the same problem: it doesn't work. You can do a search for triac dimmer power control etc. |
| soldar:
Hey, I thought I remembered doing this before! You're the same guy! https://www.eevblog.com/forum/beginners/ac-dimmer-circuit/ You just abandoned and now you start all over again? |
| floobydust:
Yeah, that thread ended after he found the potentiometer was bad and needed to replace it. |
| vidarr:
Yeah, the potentiometer was bad and I stopped. I wrote above that I posted here about it before and where I left off. I put the project on hold because this is a hobby and I had other things to do. So, now I am back at it where I left off. I just finished unsoldering one of the circuits. I am going to try an alternate circuit I found online. I WANT to understand the circuit. I understand what all the components do individually. I understand how the TRIAC and DIAC work together. I do NOT understand why the capacitor(s) and resistor(s) are sized the way they are and why they are placed the way they are. I see so much variation in the circuit designs that I can't figure it out. |
| vidarr:
--- Quote from: floobydust on September 20, 2019, 08:30:01 pm --- A better circuit adds a bridge rectifier to give "hysteresis free" or "no snapback" effect, like you see with lamp dimmers. It's also helps with inductive loads. The extra diodes discharge (reset) the firing delay capacitor every cycle. More can be found in figure AN1003.12 or Teccor App note AN1003 --- End quote --- I tried another schematic very similar to what I had tried and it did not work. Finally, in frustration, I copied a schematic from one of these Indian made, YouTube videos. Watching how they solder is hilarious. Anyway, my theory was if these guys could make this work, there is no way I wasn't going to succeed. I ended up making two of the Indian guys' circuits I found and they both worked. Go figure. So, I know my parts are good at least. I am going to try the schematic under: "Figure AN1003.9 Basic Diac-Triac Phase Control" in the link you posted. If that works, I will move on to the circuit with the bridge rectifier, as you suggested would be better. Thanks for the link to that "Phase Control Using Thyristors" PDF. That was very helpful. Thanks |
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