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.
Found in a General Electric documentation from the 1980s, this circuit makes use of a FET...
This circuit is based on an MC1408, an integrated circuit that is not common today. The...
Another way to increase the sensitivity of the circuit with the amplification of the sensor...