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.
In the figure we have a way of using a solar cell as a source for circuits with tunnel diodes. The solar...
This equalizer was found in the May 1978 issue of Radio Electronics magazine. The component values...
This circuit for high-impedance magnetic headphones was suggested as an experimental amplifier for hearing...