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 kHz oscillator (CB21934E)
This circuit was taken from the 1960's Mullard Transistor Manual. Information about the coils is...
LM386 Bridge Amplifier (CB25300E)
This bridge circuit is designed for 8-ohm speakers delivering a few watts of power. The circuit is from...
Rain Alarm (CB15108E)
This alarm, from a 1996 magazine, can be fitted with two BC548s in the original configuration...