The indicator for this circuit is a 0 to 1 mA milliammeter. The operational is from the 70s, when the circuit was published. Modern equivalent can be used.
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...