I have been utilizing a LM317 regulator on a vast number of projects with great success. However, I have a new sound module (WT558D-U) and it works OK when connected to the USB port but when I disconnect the USB port and power the sound module from the LM317 it will not operate. I know the LM317 is working because I can adjust the voltage to the 3.3VDC; I need for the sound module. I tried placing a 10K and then a 1K resistor across the load, thinking that it needed power to start working, but that did not work.

Any Ideas would be helpful.
Also, can some recommend a simple 3.3VDC?
Thank you
Brian Krupicka USA

 

USB ports are powered from the +5VDC rail.

 

I did increase the voltage to 5VDC and it still did not work. The sound module is designed to work on a range of 3 to 5VDC. The sound module draws about 4.5ma. Is this enough for the LM317 to start operating?

The LM317 was setup with:
a 620 ohm resistor between the output lead and the adjust lead
a 620 ohm and 1K trim pot between the adjust lead and ground.
Is this correct?

PS the sound module will work with 2 AAA batteries.

I can please use your help.
Brian Krupicka USA