Found ina 1970 American documentation this fast-reading circuit uses a photodiode. Transistors support modern equivalents. The circuit can be used as a shield.
This speed control for motors up to 500 mA was obtained in an old European documentation, but it...
This circuit cuts a rectangular signal, and a trapezoidal signal is obtained. The circuit is from...
This low frequency sinusoidal oscillator was obtained in documentation from the 1970s. Operational...