adjustable power supply problem! please help!

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Triton
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adjustable power supply problem! please help!

Post by Triton »

OK i built my adjustable benchtop power supply and it appeared to work perfectly. that is until i attached a load to it. it outputs proper voltage and everything (confirmed by multimeter) until you hook up something to it! as soon as you connect something the voltage drops by 50+% and i cant for the life of me figure it out! ive tried a different PSU, ive checked my schematic (see below) and my wiring several times. i spent about 3 hours so far today troubleshooting it and cant figure it out at all!

this is the schematic i used
Image
any thoughts or ideas? thanks in advanced!
nevermind1534
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Re: adjustable power supply problem! please help!

Post by nevermind1534 »

Is the wattage/amperage high enough? I don't know what to tell you.
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superdeformed
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Re: adjustable power supply problem! please help!

Post by superdeformed »

It's a little hard to tell from the reflections on the ink, but it looks like you don't have the potentiometers in the right spot (assuming those are LM350's). You should have the fixed resistor between the output and adjust pin (like you have drawn), but the pot should be between adjust and ground, not out and ground (it looks like you have it drawn two different ways between the top and bottom of the schematic, so I'm not sure how you actually hooked it up). Also, the datasheet for the LM350 recommends using 240 ohms for the fixed resistor. With 10 ohms it will be drawing far more current than it needs to, which may interfere with its ability to regulate properly.
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Re: adjustable power supply problem! please help!

Post by Rekarp »

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Triton
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Re: adjustable power supply problem! please help!

Post by Triton »

as i already told rekarp i switched the 10ohm resistor for a 220ohm resistor to no avail, it still did the exact same thing. also fooled around with different ground arrangements and a few other things and still no difference.
ill doublecheck my wiring tomorrow
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