This variable frequency (VFO) oscillator was found in a Japanese publication of 1962. Coil details (in Japanese, but can be deduced) are next to the diagram covering the 3.5 MHz band.
This simple source with zener regulation is ideal for experimental projects with operational...
This circuit is from a 1977 Signetics manual. BC107 transistors can be replaced with BC547 and...
In the figure we have an old circuit for controlling two low-power lamps. The circuit is from...