This interesting circuit for SMD assembly appeared in the November 1987 issue of Radio Electronics magazine. The phonons are generated by selected resistors that are fitted to the assembly.
We found this circuit in a 1995 publication. It makes use of infrared LEDs of the type existing at...
Relays up to 100 mA can be driven by the 555 with the recommended circuit. The circuit is from an...
The sensor for this circuit is a phototransistor. We found it in the April 1971 issue of Radio...