Electronics > Beginners
AC Dimmer Circuit
Zero999:
--- Quote from: vidarr on December 27, 2018, 02:10:58 pm ---It is these... The orange are the old. The blue is one of the new ones.
Also, I had the two resistors in reversed positions. The 12k goes between the capacitors. Does it still seem OK?
edit: I have power in. What is the next best thing to test? This may be lame, but I am still a little nervous around mains power. I don't want to be poking around in there more than needed. Thanks.
--- End quote ---
Those capacitors are marked µ1K, which is 0.1µF or 100nF or 100×10-6F and the K means a tolerance of 10%. I thought 1nF was wrong: much too small.
https://www.radio-electronics.com/info/data/capacitor/capacitor-markings.php
Have you tested the potentiometer? It's quite likely it's damaged.
It's good to be nervous about mains power. Going from the pictures, the construction doesn't look very safe. Does the potentiometer have a plastic shaft? If not, it should and a plastic mounting thread too, to ensure it has adequate insulation from the mains. If not the potentiometer needs to be fitted to a metal panel which is connected to the earth conductor.
vidarr:
The circuit was originally not in a plastic case. It was on the ground because it was the first time I tested it and I didn't want it near anything important. I left the area and my wife stepped on it.
Yes, Zero999, I think it is the potentiometer. I have a couple others, but I am not sure if they are appropriate. They have metal shafts and look very small. Yes, the original potentiometer has a plastic shaft.
I did not give up yet.
Thanks.
soldar:
A pot is extremely easy to test with a multimeter and I thought you said you had done that.
You can test the circuit by just shorting the pot and it should give full power. It makes sense that the pot would be damaged in the bad luck accident.
Note that the caps provide the delay in triggering. You can remove the caps and the circuit should provide full power.
Here is a similar circuit from my files.
coppercone2:
imo put some current through it if you really wanna test it
and hook it up to a scope to make sure it does not break contact momentarily when you sweep it.
vidarr:
I did test the potentiometer. That "scratchy" spot turned worse when I retested it. I kept turning the shaft with my multi-meter on it and the readings started to get worse and more erratic. The one spot has turned into three, or more, "scratchy" spots. It goes from no conductivity to full in about a 0.005 degree turn in those spots. It is dead. I do not have a proper replacement. I guess I have to go to the store now. Thanks for all your help guys. I will update this post after I get the replacement potentiometer.
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