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Regulated power supply design

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New Member
I am in search of some help. I am trying to build a power supply to run a basic "tank" circuit. The coils are just over 2 ohms, and I am using a 47mF capacitor in parallel with them. The power supply needs to be in the range of 1- 20 Volts, 2 amps, with a 10 turn potentiometer.
If anyone can please help me out, I have been reading books and trying to piece it together but it's been a little frustrating! :shock:


New Member


STOP THIS MARIA. :twisted:
Just count how many times you have posted this same question in the forum.


Active Member
If what you need is information on a power supply that will deliver 1 to 20 vdc at about 2 amps then look up the spec sheets on an LM338 - it's a 3 terminal variable regulator. I do not know if you can get quite as low as 1 volt. I do not know enough to describe how well regulated the supply will be but it is good enough for many applications.


Well-Known Member
The problem with a simple linear regulator is getting 2 amps over the entire voltage range (or vice versa). The unregulated supply will have to be around 25 volts, so at 1 volt and 2 amps, the regulator has to dissipate 48 watts. The usual solution to this problem is a switching regulator, but switchers generally have some residual high frequency noise on their outputs.

I once played around with a design that had 2 SCRs in the bridge (or center tapped) rectifier, and a tracking circuit that phase-modulated the SCRs to keep the voltage across the linear regulator at about 5 volts. I simulated it, but never built it, but I have no doubt it would work. You can also use a similar scheme, but with a tracking switching preregulator, if you need really clean (read linear regulator) DC. Keeping switching noise out of the output still requires careful attention to grounding and shielding.
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