Found in a 1924 documentation, this circuit is powered by 3 batteries, two of which are high voltage. The output is a high impedance headphone jack.
This is an amplifier stage with a typical germanium transistor from the 60's to the 70's. The...
Also suitable for use as a noisy alarm, this Morse Code or telegraph practice oscillator was found...
This circuit was found in ancient American documentation. Diodes are general-purpose types. |...