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.

1.78 MHz Telephone Transmitter (CB16689E)
This 1992 circuit operates in the range of cordless phones used at the time. The circuit is based...
Fluorescent Flasher (CB17350E)
This different circuit uses a relay as an oscillator, whose frequency is determined by C1, and to...
Antenna Amplifier (CB3869E)
This antenna or booster amplifier operates with signals from the midband (MW) range up to the VHF...