DC power supply question

[BMK]

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.
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.
Any Ideas would be helpful.
Also, can some recommend a simple 3.3VDC?

Brian Krupicka USA

[JoshMac]

Hi BMK,

If the sound module is ok working directly off USB and thus 5 volts, why run a LM317? have you tried running it directly off a 7805?

I havent been able to find a datasheet for the "WT558D-U" module, can you link me to it?

What would be powering the LM317?

[BMK]

I found the answer to my original question. I purchased a non-polarized 10mdf capacitor for the output circuit. Next time I need to read the packaging more carefully.

To answer your question. The members of our model railroad club, at the club and their home layouts, will run this unit at anywhere from 5VDC to 24VDC input. The LM317 can handle it easily and with the low current no heat dissipation (heat fin) is required.

As for a link to the WT588D-U, try. www.elechouse.com
http://www.elechouse.com/elechouse/imag ... Module.pdf

Product features
Package of 28 pins module, which can be replaced memory for gainting different lengths of storage
time.
Support SPI-Flash, which ‘s capacity is 2M bit ~ 32M (Note: 1byte = 8bit)
WT588D-20SS voice used as a control core chip.
Embedded human voice processor, feel very natural and sweet.
Good audio quality output for 13Bit/DA converter and 12Bit/PWM processing of audio.
Support for loading 6K ~ 22KHz audio sampling rate.
PWM output can directly promote 0.5W/8Ω speakers and plenty of current.
Support DAC / PWM output
Support for loading WAV audio format.
Support key control mode, one-wire serial control mode, three-wire serial control mode.
A variety of IO trigger ways can be seted to in button control mode.
The way of BUSY signal output can be set in a random manner.
Loading no more than 500 segments voice for editing.
Address bit is controled by 220 segments voice, but a single address bit just can load up to 128.
Voice player to enter the sleep mode to stop immediately.
It is simple interface and convenient because of using WT588D Voice Chip that benefited to exert its
functions.
A lot of operations can be finished in software. Such as setup control mode, inserting voice,
compositing voice, calling voice, etc.
Free to insert mute, mute time range 10ms ~ 25min.
Support online USB download / offline USB download. What’s more, it also can download data to
SPI-Flash even if WT588D-U are working.
Operating voltage: DC2.8V ~ 5.5V.
dormant current less than 10uA
Powerful anti-jamming. Widely used in the industrial field.


Thank you for your response.

Brian Krupicka USA