Radio Booster (CB21734E)

Found in a Popular Electronics - January/February 1969 this circuit was intended to increase the sensitivity of car radios operating in the MW range.

20 mA Current Source (CB13423E)
This source of constant current was obtained in an American documentation of 1973. The transistors can be...
Pink Noise Generator (CB17609E)
Unlike white noise, pink noise has a spectrum whose amplitude decreases with frequency. This...
Telephone Call Monitor (CB10509E)
This circuit was found in a 1985 English magazine, but it can still be easily assembled, as the...