This circuit was found in the July 1992 Radio Electronics magazine. Sensitivity adjustment is made at R6. Supply voltage is matched to that of the relay.
We found this circuit in the Texas Instruments optoelectronics manual. Field effect transistors can be...
Found in an English publication from 1977 about the CA3130, this circuit uses a probe to play a...
This circuit is from 1997 Linear Technology Applications. The circuit uses common components at...