This circuit was obtained from an American documentation from the 90's. The components can be changed, and a power step can be added for greater sound volume.
This oscillator uses a small transistor amplifier or radio output transformer. We found it in a...
Found in a 1995 Hands-On Electronics, this circuit generates a sinusoidal signal whose frequency...
This TTL circuit is from a Radio Electronics magazine from February 1973. The circuit must be...