We found this tube receiver in a 1950s Japanese publication. The circuit uses 5 tubes and has an RF amplifier stage for greater sensitivity. The power supply is not shown on the circuit.
The sensor of this circuit is a large surface diode. We believe that a small solar cell can also...
The sensor in this circuit is a BA315 diode. Other diodes can be experimented, but this is one...
This active crossover filter was obtained from the component manual used. Below is the performance...