Found in Motorola's 1967 documentation this circuit can use any general-purpose transistor. The signal should be applied to a good amplifier. The noise diode can be replaced with a common one.
This VCO makes use of components from the 1980s. The circuit can be implemented with modern...
This circuit uses an LDR as a sensor to trigger an LED indicator at a preset lighting level. The...
This circuit was found in a 1968 General Electric documentation. It has an input impedance of 2 M ohms...