Voltage Level Detector (CB22135E)

We found this circuit in an English documentation from the 80's. Transistors are general-purpose types.

Ramp Generator (CB1434E )
This circuit was obtained in a 1973s documentation. The transistors may be BC558 for the PNP and...
Variable Reluctance Preamplifier (CB12902E)
Some old record players use variable reluctance phono pickups, requiring a special amplifier...
Triac control without hysteresis (CB8154E)
This circuit was found in a General Electric documentation from 1966, It applies to any triac and...