Our partner Hugatry's HackVlog's Test for LM2596 Step-down Power Module DC Adjustable LED Voltmeter

LM2596 Step-down Power Module DC Adjustable LED Voltmeter 
http://goo.gl/ZJIJLA

Features
1、Input voltage range:4～40VDC
2、Output voltage range:1.25-37VDC adjustable
3、Output current:2A
4、voltmeter range: 0 to 40V, error ?0.1V
5、Input reverse polarity protection
6、Built in output short protection function
7、Built in thermal shutdown function
8、L x W x H =6.1*3.4*12 cm
9、Weight: 22g
10、LED digital voltmeter tube, the accuracy is adjustable function, can be aimed at your multimeter adjustable accurate.
11、Press the right key to let the display show the input or
output voltage. when the right ?OUT? led light, it shows output, the
left ?IN? led show input.


How to adjust the accuracy?

(1) Output voltage calibration steps

• Step 1,
  adjust the right button so that "OUT" LED lighted, the voltmeter shows
  the value of output voltage; Press the right button for more than 2
  seconds, release, voltmeter and "OUT" LED flashes in synchronization so
  that you enter the output voltage calibration mode.
• 
  Step 2,press
  the right button (normal speed), the voltage value is adding up a unit;
  Press the left button, minus a unit; Due to a unit is less than 0.1V,
  the minimum voltage display to 0.1V, so you need to continuously press
  1-5 times to see the voltmeter change 0.1V, how many times voltmeter
  change 0.1V by pressing the key, depending on the current display
  voltage, the higher the voltage, the fewer the number of press.
• 
  Step 3,press
  the right button for more than 2 seconds, release, to exit the output
  voltage calibration mode. All parameters set to automatically power down
  to save.

(2) Input voltage calibration steps

• 
  Step 1,
  adjust the right button so that "IN" LED lighted, the voltmeter shows
  the value of input voltage; press the right button for more than 2
  seconds, release, voltmeter and "IN" LED flashes in synchronization so
  that you enter the input voltage calibration mode.
• 
  Steps 2 and 3, consistent with the output voltage calibration method.

Note

Some customers report: "The module can not be adjusted, the
output voltage is always equal to the input voltage." When you encounter
this problem, please counterclockwise rotation of the potentiometer 10
laps or more, then you can adjust the output voltage. Because the
factory default output voltage is 20V.