This high impedance headphone amplifier was found in American documentation from the 1990s. Any general-purpose FET can be used.
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...