Headphone Amp & Battery Pack
Hey, you got USB charger in my Headphone Amp! Together, they are delicious. Something has to power it, and it’s going to live with my phone anyhow, why not also charge. It’s oddly the same size as these battery parts I have leftover. It’s also 5V. It appeared meant to be, until I discovered a problem.
It draws too little power. The battery manager board I was using thought there was nothing connected at all, and went to sleep after a few seconds. I have another battery linked below that doesn’t have this problem, and you can search for ones without this auto-power-off feature, but I found a different solution. This article. That circuit worked great. I just instead used a common 2n3906 for the transistor, and went electrolytic with the .1uf capacitor, negative toward ground of course. It only needs two wires going to it to do the job.
To run the amp on 5V, look at the picture below. That rightmost pin of the three pins on that regulator, in the yellow rectangle on the photo, that’s your +5V in. You can use any ground for the negative. I also removed the connectors circled in red.
Parts List
Easier Battery Pack
https://www.ebay.com/itm/Portable-External-USB-2600mAh-Power-Bank-Battery-Charger-for-Mobile-Phone-White/141348993687
The ones like this just work, they don’t auto-power-off, but you need to add a power switch.
———- Above is all you need really, plus a power switch maybe. You can, without soldering, just cut a usb cable, and stick it’s red and black wires into the + and – in screw terminals, respectively, and probably power it fine too.
I can’t find the exact battery manager board I used, but there’s better ones out now. Search for “usb charger board” on ebay. You can use any of them with any size and shape of these common ‘3.3V LIPO’ batteries. I used a 4000mAh one, and it seems way oversized for this amp, meaning lots of run time.
Fabulous enclosure courtesy Church Cannabis Co.
