This battery circuit provides a charging current of 500 mA depending on the solar panel. The switching circuit is from a National Semiconductor documentation from the 90s.
Using an operational amplifier, this circuit was found in the March 1996 issue of Electronics Now...
Only when the programmed key sequence is activated, and within a minimum time determined by the...
Found in a 1980s documentation, this circuit makes use of components from that time. Modern...