I'm looking for a USB charger that is 100% noise/ripple free

I have device that plugs in to my PC audio output and converts it into an bluetooth signal that transmits to my hearing aids. It has a built in battery that doesn’t last log enough.
It’s very low power so my powerbanks keep shutting down, even when they in theory shouldn’t…

Connecting to usb of my PC works, but the charging seems to have some ripple in it because I keep hearing a tick, tick tick sound.
So I’m looking for:

- a charger that outputs to a USB cable (not a battery charger)

- 100% noise free

  • a few mA output will do

A devices that cleans up the USB output of my PC would be great too.

Diy linear PS on LM7805

Mike

The ticking might be caused by the charging controller in your device, not by the power supply. Ripple would sound more like a hum.

If I charge with a powerbank there is zero ticking. (But the power bank shuts down after a while)

Maybe use something like a wall-wort, one of those phone chargers that plugs into the AC mains and has a USB output plug?

I use Apple 1A and 2.4A usb adapters for all my DACs and headphone amplifiers. I have a Schiit and an ifi zen and they sound as clean as they can possibly be.

These USB adapters are the best for sensitive equipment and they basically last forever, just make sure you are getting the REAL THING. 80% of what’s out there are fakes. Even items sold by amazon.com can be fakes sometimes, get one directly from an apple store if necessary. If you can get your hands on an older adapter that came with a phone that would be even better, most people throw them away anyways because of the new usb C adapters. My oldest one came from an iPhone 6 and still works to this day, they put in really high quality components back then, nowadays everything has been cheapen out.

https://www.amazon.com/Apple-USB-Power-Adapter-iPhone/dp/B0097BEFWC

Or, get a powerbank with low current output / trickle charging mode. https://www.amazon.com/Anker-Ultra-Compact-High-Speed-VoltageBoost-Technology/dp/B07QXV6N1B

If you want absolutely noise free power source with zero electronics in between, wire 3xAA in series.

Got a usb cable you’re willing to hacque into? Snip in half, peel’n’strip the outer insulation, get at the red and black wires.

Insert a LC filter. L can be any decent coil 1mH or more. C can be a 1000µF cap in parallel with a 10µF can in parallel with a 1µF cap if you want to go major overkill.

Just solder the blob together with 3 leads (in, out, ground) and shrinktube it if it’d fit, or just wrap with electrical tape. Ie, just try it to see if it works sufficiently, and if it does, then worry about making it pretty.

I had to do that for a hacqued-together usb-powered microphone amp, worked great, if ugly.