Alarm with relay (CB21218E)

This latching alarm circuit using relays was found in American documentation. Sensors are connected in parallel.

One Quadrant Logarithmic Converter (CB15070E)
This configuration was found in an American publication from the 90s. Operators admit equivalents just...
TTL Oscillator (CB12678E)
The circuit shown in the figure has basically the same configuration as any TTL oscillator, with...
Tone decoder (CB19927E)
This circuit with the PLL567 serves as a decoder for PWM modulated signals of frequencies up to...