Low Voltage Vacuum Tubes
As part of my delvings into things vacuum tubes, I of course found that many others have been down this road, including this rather interesting receiver built by Alan Yates. Being a novice at this, I was intrigued by the fact that his circuit used the 12DZ6 tube, which could apparently be powered by ordinary 12 volt supplies. Its application was in automobile radio circuits, where high voltages were inconvenient (when needed, they were often generated by “vibrators”, which created an AC voltage from a DC battery voltage, which could then be stepped-up by a transformer). When I mentioned this to Tom, he thought (as I did) that it was odd, and that he didn’t understand how tubes could operate with such low plate voltages. But of course, if you search, you shall find, so I uncovered this terrific page that describes some theory and circuits that use these low voltage (and presumably safer) tubes in radio circuits. Nifty.