We found this circuit in an American publication from the 90s. It generates pulses that can be modulated in amplitude. The supply can be done by voltages from 5 to 12 V and the frequency depends on C1 and C2.
Found in an Electronic Design from the 80's, this circuit monitors the charge of a 12 V battery....
Found in an EEE from 1970, this circuit supplies a voltage of 12 V DC x 10 mA current from the...
Using old germanium transistors like the CK722, this circuit has good gain. We found it in a...