I am trying to powr an old test instrument with a dead supply.
What would be the most straightforward way to make a regulated DC power supply with the following four voltages plus earth reference?
0V (Earth reference)
-6V
-12V
One possible option might be to use a 1A 12VDC regulated plugpack, and build from there. I assume that would eliminate the need to regulate the remaining three voltage outputs separately.
Thanks for any suggestions.
David King
Most straightforward? Four of these:
and a sixteen-pack of alkaline D cells. (or four four-packs, etc.)
Wiring the assembly appropriately is left as an exercise for the student. ;-)
Cheers! Rich
A power supply with +/-12VDC output and a couple of linear regulators (eg. LM317/LM337) and a few passives would be pretty easy. If the current drain is really 250mA per rail then it will dissipate an additional 3W in the regulators (1.5W each), so they'll need small heatsinks.
If it's a sensitive instrument you might need to pay attention to the quality of the supply (for example, ripple on some or all of the rails).
Best regards, Spehro Pefhany
you could power it with a 12V AC wallwart and make the dual supply with a full-wave voltage doubler, lots of modems use an AC wallwart I assume that is what they do
-Lasse
I would go for a +/- 5v regulators a diode voltage drop above ground.
Unless you can get a LM7806
and a 7906
Mouser also has OnSemi 6 volt regulators.
I think the +/- 12v would be trivial.
Cheers
[+/- 12/v, +/-6V]
If you can find it, a suitable transformer with 24VCT and
12VCT windings will suffice; ground the two center taps, and each of your four supplies consists of two diodes, a filter capacitor, and a three-terminal regulator. DigiKey lists a Tamura PFT24-28 for a little under $30 that'll do the transformer part.If you prefer to use prebuilt modules, though, it'll take a lot of catalog search. It's more likely you'll find
+/- 12 and +/- 5V (and shockingly high prices for off-the-shelf).
Fix the dead supply. Be like Frankenstein, bring it back to life...
+/-12v is easily mad with 7812, 7912 and a 12-0-12 iron, or just a 12v wind and half wave rec. +/-6 is easily made from those rails with 2 more 78/79 regs.
Or if 5v rails are adequate, just use a pc psu.
NT
(...)
That's 'Fronkensteen'.
--Winston
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