This is the traditional voltage follower configuration with the 741 operational amplifier. The circuit is from 1976 documentation and the power supply must be symmetrical from 6 to 15 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...