This circuit was found in the December 1977 issue of Radio Electronics magazine. The 4-digit circuit is based on TTL logic and must be powered by a voltage of 5 V.
Using a CA3130 operational amplifier, this circuit was found in an English publication from 1977....
The purpose of this circuit is to transmit the signal from a guitar pickup to an FM receiver...
This direct coupled circuit operates in class AB with good gain. The circuit is powered by 12 V....