This circuit is from a 1966 publication. The frequency depends on the capacitors and on R1 which can have values between 47k and 2.2 M typically. The supply voltage can be between 200 and 300 V.
This antenna for the frequencies 146 or 440 MHz was found in a magazine 73 for Amateur Radio of...
This circuit produces 1 kHz square signals using the CMOS IC 4070. The frequency is given by the...
Found in a 90s PE Hobbyst Handbook, this circuit mimics the sound of a space gun. The components...