This crystal or galena radio was found in documentation from the 1990s. The earpiece must be a high impedance crystal or magnetic earpiece and D1 can be any germanium diode.
The proposed circuit generates signals in the range between 9 kHz and more than 44 kHz, which, it is...
This circuit uses currently uncommon components, including the 10.7 MHz (FI) filter. This circuit was...
This small power supply for low currents (5mA) is suitable for power low-power TTL experimental circuits....