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, which I imagine is related to the lack of Vref, is that the output voltage is roughly 1.2 to 2 volts less than the input voltage. These problems are consistent across multiple lm317s and i have checked for any cold joints or open circuits. Perhaps it is the placement of the the components that is causing all of this. Is the 1.25 reference voltage created by the chip itself or by R1? How should adjust be connected to output? I am using a 330 ohm for R1 and 10k pot for R2, along with the recommended capacitors and diodes and the schematic in the datasheet. If any of you could help me or point me in the right direction it would be much obliged.
Thank you,
Jacob
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, which I imagine is related to the lack of Vref, is that the output voltage is roughly 1.2 to 2 volts less than the input voltage. These problems are consistent across multiple lm317s and i have checked for any cold joints or open circuits. Perhaps it is the placement of the the components that is causing all of this. Is the 1.25 reference voltage created by the chip itself or by R1? How should adjust be connected to output? I am using a 330 ohm for R1 and 10k pot for R2, along with the recommended capacitors and diodes and the schematic in the datasheet. If any of you could help me or point me in the right direction it would be much obliged.
Thank you,
Jacob