Solar Powered Code Practice Oscillator
Here is one of the most effective Morse Code practice oscillators you will ever find. No batteries and no power line connections are needed.
All you need is enough light, and you're in business. The Solar Cell provides all the power required. This Cell is sometimes referred to as a "sun battery". The photons of light energy are converted directly into electrical energy.
There are two common types of Solar Cell available today: the selenium cell and the silicon cell.
The silicon cell is very efficient in changing light energy into electrical energy, but it is very expensive.
The selenium solar cell is not nearly as efficient in converting light energy, but it is much cheaper.
The selenium cell demonstrates all the characteristics of a solar cell, and the Solar Cell in your kit is of that type. This circuit may have any component values changed without fear of damage, because of the low power supplied by the Solar Cell.