Like the previous circuits, this one uses a small speaker as a microphone and has two amplification stages with 600-ohm output.
By pressing and releasing PB1, only one LED is lit, drawing a number from 1 to 6, as in a die. The...
We found this circuit in the National Semiconductor Linear Applications Handbook of 1994. The...
The transformer inf this circuit is a 6 or 9 V unit and diodes 1N4002. The filter capacitor is 2...