This circuit was found in a Popular Electronics from April 1993. It is a voltage regulator circuit for solar battery. R1 and R2 determine the output voltage as a function of the number of cells. This circuit is a switched regulator for 15 mA output with a voltage of 7.2 V but reaches 51 mA with 3.3 V. R1 has values between 10 k and 100 k. Check the availability of the integrated circuit before starting for assembly.
