We found this circuit in a 90s Popular Electronics. The circuit can be implemented with modern components. The power MOSFET is according to the controlled load.
We found this circuit in a Motorola documentation from 1968. Phototransistors are common and...
This circuit was obtained from a 1978 Practical Wireless. It makes a speaker emit sound when there...
This circuit was found in Sprague Electric documentation from the 90s. The circuit uses a...