This goes back to my late teens, in the EARLY 1980's. I created a gizmo using various parts and pieces, where I could use it to play any radio station I wanted through someone else's radio. It was most often used at a local 24 hour donut shop, where I hung around with a group of guys until the wee hours. The owner of that store had a radio in a locked box in the back, that piped a local "elevator music" station through the store's speakers. Since it was locked, nobody could change it... until I came along. :)
The idea was simple... I took apart an old "FM converter" (remember those? To listen to FM on an AM-only car radio) and fed the audio output into a homebrew FM transmitter. It was powered by a 7AH 12V gel cell, so it had plenty of power for all-nighters. The guys would really get a big kick out of the fact that I could adjust everything... volume, bass, treble, and what station we heard, from a booth in the lobby. Naturally, the local rock station was the music of choice.
In later years, I adapted that transmitter to work with a "walkman" cassette player, and if a restaurant was playing a radio, I could put my tape onto their speakers for the duration I was there. :)
Now, I'm a Broadcast Engineer, and also a ham radio operator. Hacks are a part of everyday life... but not like this, anymore. I could get away with it when I was a teen, not as a 50-something.
