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goldenreference low voltage power supply


kevin gilmore
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So, having a couple problems myself, of my own making. Built one for 15VDC. Positive rail is fine at 14.98VDC. The issue is the negative rail. I'm powering it up with a variac connected to a spare transformer and it will kick over and light up all the LED's at around 18VAC. The issue is raising it to line voltage, the negative starts at -6VDC and just keeps going up as AC input increases. I backed it off once it hit about -23VDC.

 

I swapped the Opamps and the Voltage Reference chips and same result so those aren't the issue. The MJF1531G was getting warm. I'm guessing the problem is with it or the Jfets? All the right parts are in the right places, but I bet something got toasted when I originally accidentally started it up with an MJF1531 in the MJF1530 slot.

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I'd probably start with replacing the MJF15031 that you had in the wrong spot, and now is getting warm. Also, I would think that you should be able to get 15Vdc out with 15Vac in, since that would be ~19.8Vac after the rectifiers? And there aren't any Jfets in this.

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  • 2 weeks later...

Trying to power up a laptop, a bit silly though. laptops always using SMPS

Any plan to release a active crossover board (analog active), three-way, or four way, with discrete stuff? For diyers who are messing with diy speakers, that would be a great news.

Many active crossover boards on the Internet sounds like ****, contain tons of op amps, disappointed

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it would be insane to use this supply to power a laptop. much cheaper to buy a power-one for the right voltage and size

a number of companies now making linear power supplies to run desktop computers. they are gigantic. And with the latest 6 and 7th generation intel cpus with the 12V only supplies that are rated at 20 amps or more, also silly to do linear.

no plans on crossovers. I certainly know how to do them, but lots and lots and lots of parts

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  • 2 weeks later...

So I think this is pretty cool (sorry to toot my own horn, but I can't help it sometimes :)). 

I've been meaning to miniaturize the GRLV supplies.  I've got them down to boards that are 1.16" (H) x .8" (W). 

The output transistor mounts to the board and you can mount it directly to heat sinks.

They are designed as LM78xx and LM79xx except with a TO-247 footprint.  This means you'll still need the supporting components (bridge, diode and a few caps) that are found on the current boards.

Here's what they'll look like...

GRLV78xx-F.thumb.jpg.4486564e8e1f09b9cc971d617097da22.jpgGRLV79xx-F.thumb.jpg.c7c6f5100a5c05d18568fd6a98e014aa.jpgGRLV78xx-B.thumb.jpg.36a4afb8a138d8e6f1c3aaaf937face1.jpg

 

Note that the pass transistor will be folded up on to the board and you'll need to put some mounting pins in.  I've made it so it is the same size as a standard horizontal TO-247 mount.

EDIT:

Note that there are set resistors are on the board (R2, R3) so the boards act like fixed regulators in the circuit.

Edited by Kerry
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I was thinking about it as I was doing the LV one.  I bet I can get it close to that size wise. I'll add it to my list, so definitely not by end of day :o

Maybe do the T2 PS style current limiting, which is better at handling shorts.  Let me know what you think.

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