Electronics > Projects, Designs, and Technical Stuff
Low noise, portable +/- 12V PSU
moffy:
I was trying to do some noise/distortion measurements on an audio VCA I had made but I was getting 50Hz noise from my power supply. I was looking for around 100/110db of resolution for my measurement system. Even if I moved the wires a little the 50Hz noise would fluctuate, obviously induced pickup. So I went for a simple, cheap solution. Bought 2, 12V/2.4AH gel batteries from Jaycar and some terminals, and voila, a low noise power supply which is portable and completely isolated, so no ground loops.
Testing went very well, unfortunately my VCA had around -80db of signal distortion. But the test setup, a Steinberg UR44 external sound card and my laptop had around 110db S/N ratio with the battery supply. For charging I already had one of those PRO type chargers that do multiple chemistries.
Perhaps others might share any mildly unusual battery supply stories, I'm sure they would be interesting. :) :) :)
NiHaoMike:
Were those really cheaper than using NiMH AA batteries?
moffy:
Yes, especially from Jaycar. Simpler too, just cable tied them together no battery holders. :)
David Hess:
I have used stacks of AA NiCd cells in the past to do the same thing. Batteries make fine low noise floating power supplies.
Gyro:
You'd be well advised to add a couple of in-line fuses, otherwise it's only a matter of time before the insulation drips from your wires and the tracks lift off your PCBs. ;)
It won't hurt the noise performance.
This style is compact and easy to find... https://www.ebay.co.uk/itm/5x-Inline-Standard-Blade-Fuse-Holder-Splash-Proof-DC-12V-30A-Fuses-For-Car-Bike/132727931095
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