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.

Operational RIAA Preamplifier (CB14846E)
Common operational amplifiers like the TL series, CA3140 and others can be used in this circuit...
76 dB Gain Preamplifier (CB25695E)
This high-gain amplifier was found in the March 1994 issue of Electronics Now magazine. The...
Process timer (CB21865E)
We found this timer for times of a few minutes in a 1974 Ferranti transistor manual. The relay is 37...