1. L

    LM317 no reference voltage

    Hello all, This is my first post so forgive me if I break any rules, I am trying to create a variable voltage power supply using an lm317 but am running into problems. For starters, it doesn't seem that I have a vref voltage, when probed I get 0 volts across input and adjust. My second problem...
  2. P

    LM 317 behavior as a current regulator

    Using a LM3117 as a current regulator to control the current applied to a 12 V yellow LED and to a 5mW green diode laser, I found a difference in the behavior of the LM317 when controlling both LED and laser. I tested the circuit with three different resistors. Here the values and the...
  3. pravardhan

    LM317 as LED driver with two constant output current selection

    Hi All, I wanted to have the LM317 as LED driver for the DRL (Daytime Running Lights) in my car. I want the DRL current to be 200mA and have chosen 6.2 ohms. Now I want the DRL current to be 50mA when I switch on the Fog lights, hence I have chosen 25 ohms (if this is non-standard then I will...
  4. Amir Mohammad Soltanpour

    Variable Current Lead Acide Battery Charger

    Digitally controlling charge voltage with some regulator like Lm317 is a matter of using some resistor and transistor as stated in lm317 datasheet to select from multiple pre defined voltage. But what about choosing output current ? How it can be adjust with digital signals from...
  5. Y

    Help me understand this variable power supply circuit.

    Hi guys, I was hoping that you could explain the following circuit used in a variable power supply. It consists of an LM317. 1. I don't understand what the two diodes V5, V34 and zener diode V8 is used for? What kind of a 'magic' does that bit of circuit do? 2. The JFet is used as a variable...
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