This circuit oscillates in the fifth harmonic of the crystal frequency. The circuit is from a 90's documentation. L1 must be according to the desired frequency.
This circuit was found in a British documentation from 1969. It can be implemented with modern...
A simple VCO using two inverters in a ring configuration is shown here. A VCO is a circuit in...
The four gates of a 40111 IC are used in thes two-out circuit. The output chages their state in a...