This circuit is from a 1968 documentation using one of the first integrated circuits available at the time, the TAA370. The circuit is powered by 1.3 V using a 200 ohm handset.
This triac circuit was found in the October 1987 Radio Electronics magazine. The triac is...
This circuit was found in a 1987 edition of the United States' Hands-On Electronics magazine. The...
We found this TTL circuit with the 7400 in the January 1975 Radio Electronics magazine. The power...