LM317T Voltage Regulator with Pass Transistor

Digital Voltage Selector www.jakeselectronics.net I wanted to write a program for a 16F84A to be able to select different voltages by the press of a button. How it works, Each time the button is pressed the PIC scrolls through output pins (putting them high, one at a time. I'm using 3 pins) Each pin is connected to a transistor. When selected, the appropriate transistor pulls a resistor into play, with the reference pin of the LM317 (variable voltage regulator) and in turn changes the output voltage. At the same time as scrolling through the 3 different outputs (or simply setting one of the 3 output pins high, the chip tells the LCD to display the set voltage. (In the video the LED's up the top of the board are simply showing which pin is high, RB5,RB6 or RB7)



http://www.youtube.com/watch?v=u9WnRJWtQ64&hl=en