This circuit generates short pulses. The transistor can be a 2N2222 or BC548 and the frequency is given by the resistors and the capacitor that can be changed.
We found this circuit in a November 1970 Radio Electronics. It uses a PUT or programmable...
We found this circuit in a technical documentation from the 1970s. It converts low frequency...
This modulated siren was found in the December 1974 issue of Radio Electronics magazine. A higher...