LM 317 Voltage Regulator. Design Note 16

LM 317 is the popular adjustable voltage regulator IC commonly used to make variable power supply. It is a three terminal device with Input, Output and Adjustment pins. Actually, LM317 is an Op Amp with relatively high output current capacity. The Inverting input of the Om Amp is Adjustment pin, while the Non-inverting input is set by an internal band gap voltage reference which produces a stable reference voltage of 1.25 volts.

Solar Power Supply. Design Note 15

You can make this Solar Power supply as your work bench power supply for testing prototypes. It delivers variable voltage from 1.5 volt to 12 volts with a current up to 300 milli amperes. It can also be used to charge batteries during day time. By using the Pot, it is easy to set the output volt from 1.5 to 12 Volts.