Found in a 90s 303 Circuits, this circuit triggers a load from a 50 mV audio signal. When the signal ceases, the charge remains active for 2 seconds.
This circuit of a few tens of milliwatts of power requires a single source. We found it in a Radio...
This circuit is suggested by Texas Instruments in his Optoelectronics Sourcebook. The transistors...
This circuit used in signaling for boats, cars or barriers was found in a 1980s documentation. It still...