This modulator amplifier for transmitters was found in a 1947 American book. The circuit uses an output with 4 tubes connected in parallel and in push-pull.
This voltage-controlled oscillator or VCO was found in a Radio Electronics magazine from July...
This signal follower, from a publication from the 1970s, uses old germanium transistors such as...
This watch uses a liquid crystal display. The circuit is from the 80s and the module used is...