Seventy years ago this month, the December 1948 issue of Radio Electronics featured this serviceman’s account of his successful diversification into the coin-operated radio business.

While the author pointed out that potential markets included lunchonettes, beauty shops, and hospitals, he had so far exclusively provided radios to hotels.

While the radios were adjustable, the author had his set to play one hour for 25 cents. The average income from each set was about $3 per day, of which 25% was shared with the hotel owner.

To deal with the “familiar towel-and-soap stealers,” the set was fastened to a small table, which was in turn bolted to the floor. In addition, the author added a burglar alarm, which consisted of a microswitch in the radio’s case. If the radio was removed from the table, a bell would sound, and a lamp indicating the offending room would light in the manager’s office.