This circuit, based on a 555, was found in a Popular Electronics from the 90s. The circuit has the frequency determined by R1, R2 and C1.
With the components indicated, the circuit oscillates at 20 MHz. The coils and capacitors can be...
The trigger shown in the figure, built around a 4093 can generate pulses that reach 1 hour with a...
This circuit was obtained in an old American documentation, remembering that the 566 is the double...