[ARC5] Audio Booster Part 2

[Robert Eleazer]

As y'all might recall, I wanted an audio booster I could plug into my airplane radio and get a little more volume for weaker signals.  I found a little 3W audio amp at All Electronics and put it in a small aluminum box, powered by 3 AAA cells.

Eventually I found out that the little amp uses three different grounds, one for each side of the stereo output and one that is the same for both the audio input and the power input.  The audio output and the audio input cannot use the same ground; the circuit does not work if you tie those two together. And since the airplane uses a common ground for everything that means not only that you cannot use a metal faceplate to mount the imput and output jacks, but you also need an isolation transformer on the input.  I made a plastic faceplate out of Lexan and used a Radio Shack 1000 ohm CT to 8 ohm secondary transformer that I happened to have on hand.

It looks like it is going to work in the airplane, the only question being if it provides enough audio boost to do some good.  And since I have a couple of discarded plastic cased stereo speakers on hand I plan to buy a couple more of those little amps and install them in the speaker cases for use with boatanchors.

Wayne
WB5WSV            

---
This email has been checked for viruses by AVG.
https://www.avg.com
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/arc5/attachments/20210322/d48d1002/attachment-0001.html>