Found in Popular Electronics from the 90s, this circuit mutes a scanner's speaker in the absence of a voice signal, thus eliminating the hiss.
PIC18F “K40” Features Intelligent ADC with Filtering and Signal Analysis Capabilities Ideal for...
This simple 80's CMOS game was found in an English magazine of the time. It appears elsewhere on this...
The function of this circuit is the same as the previous one. The difference is in the use of an...