The Amīcaflex 4 transistor reflex radio

[Amie]

.... Note there is no load resistor between the detector diode and coupling capacitor....
Geordie McBoyne.

Hi.

There are a few circuits that have been published that have a "floating detector". It's something that shouldn't work but often does. I've discussed it with the more knowledgeable, and the consensus amongst those who accept it works is that it's either caused by capacitance across the junction of a germanium diode or it's reverse leakage.

Some designs use an RF transformer to feed a single diode, or a capacitor and choke to ground, for DC reference, but the double diode detector provides its own reference and more output, though the cost of the semiconductors was a big consideration in the 1960s I suppose.

The circuit I've used in this project by using sand transistors rather than soot, means that the diodes also have to be silicon, otherwise the transistor would be biased off.

Thanks.
Amie.