If you have the skills and can get your hands on SMD components, you can assemble this small amplifier. We found it in the Radio Electronics Experimenter special edition from 1990.
The integrated circuit of this pulse generator is 4093 and the frequency can be between a fraction of...
The figure shows how to implement a stage with an emitter follower. The stage has high input...
This circuit is an improved version of the previous ones with the LM3914. We found it in the March...