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Bench top power supply with 9 volt and 1.5 volt outputs? Answered

I am buidling a benchtop power supply from an ATX power supply.  I understand using the color codes how to accomplish  12v, 5v, and 3.3v connection connection ports.

How could I add 2 more power ports for 9v and 1.5 volt?

Basically I am trying to minimize the use of batteries in my testing with most common power sources.


I have read a little about the -12v and -5v being obsolete power options.  Is there any need for these voltage outputs for a newbie electronics hobbiest?

Thanks,

TRU

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Best Answer 3 years ago

Get one of those switching buck regulators off amazon or eBay. They pretty much all use the same LM2596 chip, (or for the especially cheap ones, counterfeit LM2596's that lack protection circuitry inside)

They are all pretty cheap and most of them let you vary the voltage to whatever you need, and allow for up to 3A peak (2A continuous) maximum for a short duration.

www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=buck+converter&rh=i%3Aaps%2Ck%3Abuck+converter

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3 years ago

Negative voltage rails come in real handy when you are working with analog stuff, like DC amplifiers and op amps. some DACs and ADCs require negitive voltage rails so they can convert positive and negitive voltages to numarical values.

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Nighter3D

3 years ago

Well. the easiest way to get 9v and 1.5v is the use of a Linear Regulator or 2. For example for 9v look up the 7809 Regulator. 12v goes into it, 9v comes out. Or you could use a LM317. LM317 is much like the 7809 except you can configure it with 2 resistors to get anything.

Should note: Linear regulators work by dissipating the excess energy as heat. the more current you draw the hotter they get. if you want to draw a substantial amount of power you may want to use a heatsink or considere using DC-DC Step-down regulators instead. they are more efficient.

Personally in this case: I would use a 7809 regulator connected to the 12v for the 9v supply and a LM317 configured for 1.5v connected to the 3.3v or 5v line. if one has the space i would give them both a small heatsink Just in-case.

PS: Negative supplies aren't obsolete, well maybe in computers, but with stuff like Audio having a negative supply is pretty handy!

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Downunder35m

3 years ago

Simpy use a voltage regulator or if you need serious power levels a step down converter.
The 9V can come from the 12V line, the 1.5 from the same or for really high power from the 5V line.
Same if you need a lor of power from the 9V - better to use a step up converter on the 5V line than a step down on the 12C line.