I made one of those years ago: read about it first in the late freat FRETS magazine. It was billed as a simple acoustic pickup, and cost only a few dollars and a little frustration. I tried it on guitar, banjo and mandolin, with it finally ended up being used exactly as you say, as a tuning aid on my autoharp, (unsightly to say the least). I tried using it as a pickup for amplification, but there were too many problems and it just didn't sound good.

If all you want is a tuning aid, it's ok, but why not get a real pick up you can amplify (if need be). My playing style is kind of soft, and it really helps me when playing with guitars, basses etc.

I have tried everything from Barcus Berry types to studio mikes to lapel mikes. I now use a new Pick-Up The World polymer film that mounts out of sight on the soundboard under the tuning bars. It sounds better, more consistently, than anything I have used. The Radio Shack buzzer just won't pick up all the strings no matter where you put it, and microphones are so prone to feedback and positioning.

If you're interested, check out pick-uptheworld.com, which is their web page. Apparantly these things have been used successfully in Grand Pianos.

P.S. I apologize for the length. I see most people only post two or three sentences, but I like to write. I'm also new here and not an official "member", but have surfed in occasionally for the past year, and found out that Willie Nelson wrote "The Night Life", which had me stumped for twenty years. And leave it to my nine year old daughter to find the Mudcat Kid's Page, and hence thecomplete lyrics to "It's Only A Pee-Pee". wish I knew the tune. Thanks for your patiece, I hope they don't edit this thing for length!!! Apologies if there is another BlueJay, I picked it "cause that's what an old railroader usedto call me. Bye.