The LM3909 tone generator integrated circuit of this application is uncommon nowadays. The circuit can operate on a single battery and is very sensitive.
This circuit shows how to control an astable configuration using the 555 IC. The control signal is...
Found in the August 1994 issue of Electronics Now, this CMOS circuit uses the 4046, which is...
This is the transmitter for the previous circuit. We found it in a 90s Electronics Now. The...