Transformerless Power Supply

313

06:49:04

Use a 5 W 220 ohm resistor and a 1.8 uF 200 V Polyester Capacitor. Use Zener diodes according to the desired voltage output. The max current is about 70 mA

published 7 years ago

eekee

7 years ago

Very simple but effective! :) Only, the source amplitude should be 170V for US mains. I assume that's just a little slip, because your 70mA looks like an RMS value. (It's around 80mA RMS at the full input voltage.) Or do you live in a country with 90V RMS mains? :)

eekee

7 years ago

Output voltage seemed a little low until I changed the Zeners resistance to a realistic 7Ω, so that's all right too. I fixed the input frequency too, and gave it a 1kΩ load, and it's just right. Well done!

eekee

7 years ago

http://everycircuit.com/circuit/5872513119944704

darkphoenix2711

7 years ago

Interesting! but do you get zener diodes at a high enough rating for this to work?

hurz

7 years ago

@ivanrosales, the 220 Ohm resistor does burn 28.5 Watt!! So suppose to be at least 30W. Thats waste of energy.

eekee

7 years ago

@darkphoenix2711, peak dissipation is less than 3W, continuous is less than 1/2 that, maybe 1/3. Comparing 1N4733, it's well under peak current, but I think may be a little over its continuous current rating. Of course, the 1N4733 has 7Ω resistance to these diodes' 1Ω.

eekee

7 years ago

Make the resistance realistic, and peak dissipation climbs over 4.2W. This is also waste, which I didn't mention before. It's larger than I thought, at 8.4W for the 2 Zener diodes.

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