Modulated light receiver (CB21790E)

We found this circuit in a Mullard manual from 1960. The transistor is a phototransistor of the time. The gain is 3 dB.

Flame Detector (CB17581E)
This circuit detects the presence of a pilot flame in heating systems by the presence of infrared...
SUS Frequency Divider (CB19903E)
In the figure we have a circuit that uses unusual components, being indicated for low frequency...
Triangular and square generator (CB21449E)
Found in older Signetics documentation, this circuit generates signals from 30 Hz to 25 kHz....