Sciencemadness Discussion Board

Laboratory power supply constant current

Mildronate - 19-11-2012 at 00:50

I had made laboratory power supply 270w 25V with 270w transformer (recoiled), 50A diode bridge, lm317 and 3 pararell TIP35C transistors, Anbody can sugest good and easy way to make constant current regulator for this project? Here is bad qulity pictures :) schematic i will post later.

Pastaisitais_baroklis_2.JPG - 93kBPastaisitais_baroklis_3.JPG - 82kBPastaisitais_baroklis_4.JPG - 87kB

WChase501 - 9-10-2014 at 14:40

Pulse width modulator on the line side, used to control output current.

Metacelsus - 9-10-2014 at 15:25

If you don't mind dumping power as waste heat, you could do something simpler, like:


current limiter.PNG - 5kB

semiconductive - 21-11-2023 at 23:36

How constant of a current do you want?

A light bulb filament happens to be a decent current regulator in many simple situations. The cooler the bulb gets, the lower the resistance, and the more current tries to flow.

WChase501's idea isn't bad, either. Depending on what you want, a small microcontroller (PIC16F505), + a few power transistors and opto-isolators, and you can easily regulate current. You can also use scrap PC power supplies that have the line side rectifiers, inrush protectors, capacitors, and transistors so you don't have to design most of it, yourself.






woelen - 22-11-2023 at 03:55

You could use current-based LED drivers. They are very efficient and allow the resistance of the load to vary over a wide range. Some models allow voltage to swing from 0 volts (shortcircuit at output) to as high as 80 volts. You can combine them by placing them in parallel, allowing higher currents.

Texium - 22-11-2023 at 06:49

Sorry y’all, not sure if you noticed that you’re replying to a nearly 10-year-dead thread. I’m still in the process of moving threads to the new subfora, so old ones are floating near the top.