Questions tagged [capacitive-power-supply]
10 questions
10
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4 answers
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 little, so they're not as bright.
The…
polemon
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1 answer
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 (likely 5 V at 500 mA at the absolute…
Prototype_Zero
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4
votes
3 answers
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 are shown below.
In this case, the two glass…
Amr Bekhit
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2
votes
2 answers
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 this circuit diagram.
user595628
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vote
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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 keeps failing. The circuit works for a couple of seconds and suddenly the transistor…
Mohamed Gharib
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1
vote
1 answer
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 reasons:
Capacitors are more isolated than…
1
vote
2 answers
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 one of our own design commercial three-phase…
Rohat Kılıç
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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 off the power repeatedly) the resistor got sparks…
Hazardous Voltage
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4 answers
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 just 5mm LED. (I replaced it with a regulator…
Hazardous Voltage
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What is the alternative for a capacitive power supply?
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 capacitive power supply because it has high…
Hazardous Voltage
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