This TTL circuit was found in a 1978 technical documentation. The power must be supplied with 5 V. It converts ASCII characters to hexadecimal.
This 1995 circuit uses an audio amplifier that is no longer common today. However, other...
The frequency of the tone produced by this oscillator depends on the amount of light falling onto...
This circuit was obtained from an old American documentation, and practically any general-purpose transistor...