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Questions tagged [capacitive-power-supply]

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0 votes
2 answers
107 views

Why is the Relay "Chattering"?

I have this circuit which measures if there is under/over voltage from the AC mains voltage and it consist of two parts: Part one: measuring the input voltage (I had it cropped because it is not the ...
Hazardous Voltage's user avatar
0 votes
1 answer
248 views

Why are SMD components not good for high power applications?

I have been using this capacitive power supply to drive a circuit (an OP amp and relay), but what I can't understand is that when I tried using an SMD resistor (R2) after some testing (turning on and ...
Hazardous Voltage's user avatar
0 votes
4 answers
449 views

Why is the LM7812 getting hot in this circuit?

I have made this circuit. It works fine with normal Zener diode, however when I replaced it with the LM7812 it works fine but as time passes the regulator keeps getting very hot although the load is ...
Hazardous Voltage's user avatar
0 votes
2 answers
184 views

What is the alternative for a capacitive power supply? [closed]

I am trying to make a UPS, which will need to pass safety regulations. I need to detect: When the mains AC voltage is present When the mains AC voltage is under/over voltage I thought of using a ...
Hazardous Voltage's user avatar
5 votes
1 answer
290 views

Any thoughts on a supercapacitor battery project?

Just some insight: I am fifteen and have been researching capacitors for a while now. I have come up with the idea of building a supercapacitor power supply unit solely to power some small electronics ...
Prototype_Zero's user avatar
1 vote
2 answers
361 views

Transistor keeps failing in a capacitive dropper circuit with TRIAC

I'm trying to build an automatic night light circuit based on some designs I found online. Here's the circuit I built: The problem is that the transistor BC327 ...
Mohamed Gharib's user avatar
10 votes
4 answers
1k views

Night light broke after trying to dim LEDs

I purchased a cheap night light that plugs directly into a 240V wall outlet. It has three color changing LEDs. The problem was, those LEDs were way too bright. I decided to modify that night light a ...
polemon's user avatar
  • 1,097
4 votes
3 answers
1k views

Use of different diodes in a bridge rectifier

I'm repairing the circuit for a motion-activated LED light. The PCB uses a capacitive dropper circuit as the power supply. Photos of the PCB and the corresponding reverse-engineered power schematic ...
Amr Bekhit's user avatar
  • 1,298
1 vote
1 answer
109 views

Why using capacitor in transformer less ac to dc converter

I saw many transformer-less power supplies using capacitive resistance of a capacitor. But I don't know exactly what the reasons are for using capacitors instead of normal resistors . I guess two ...
MohammadAli Zeraatkar's user avatar
2 votes
2 answers
773 views

Capacitor Vrms vs Vpeak Rating in Transformerless Supply

Why is it that when calculating for voltage across the capacitor in transformerless power supply we need to use peak voltage not RMS voltage value. To be clear I am referring to the rating of C1 in ...
user595628's user avatar
1 vote
2 answers
1k views

Connecting DC Common Node (Ground) to Three Phase Neutral

I know I shouldn't. But I just wanted to ask due to a specific requirement. I also searched the forum but couldn't find any similar question. Please give me a link if there's any. I'm asked to modify ...
Rohat Kılıç's user avatar