The Triac trigger integrated circuit is not very common nowadays. The circuit was found in the Radio Electronics Experimenter magazine from 1989. The triac should be in accordance with the heater.
This circuit was found in many record players with crystal phono pickups. The output power is 800...
The 8038 is an integrated waveform generator (sinusoidal, triangular and rectangular) from...
This protector was found in an Electronics Now from the 90s. The 250 V transient suppressors are common...