This circuit triggers a Sonalarme when the LED used as a sensor receives light. The circuit was found in an old documentation, but the components used are all current.
This powerful sound emitter used in defense to intimidate people was found in a 90s Popular...
With this circuit it is possible to control a relay up to 100 mA with an extremely low input...
In the figure we have the basic configuration of an inverter transconductance amplifier, as...