XY-SK120X  buck boost converter - Current calibration - Page 1
Forum section: electronics / projects

author: Fluxia
author_rank: Contributor
timestamp: February 03, 2025, 12:35:55 pm
content: Hi all , not sure if this topic should be in the beginner section...I have recently made a DIY bench power supply using my old computer PSU. I bought a buck boost converter (XY-SK120X) from Ali express to have a variable voltage supply as well. The project is fairly simple and I have attached a sketch (there are other part that I have not included in the sketch ie fuses, swath, led, and USB socket). There is dummy load attached to 5 v ( I have put a switch on it as well, as it does not appear to be needed, but I understand it can improve the voltage stability(?)....The issue I am having is the following:The current measured by the XY-SK120X does not match with my tester when I attached a load of 10 Ohms to the variable voltage (output of XY-SK120X). You can see it in the picture. Also I noticed that switching the dummy load on an off affects the Amp measure of the XY-SK120X even though the dummy load is on a different line . I don't understand this.This is the third buck boost converter that I purchase sending back the other two (different models : XY-SK120) that presented with the same problem. Initially I thought that they were cheap and probably defective items but as this is the third attempts and the same problem I start to doubt...The module has a calibration setting for current and voltage, but there is nothing on the web to help using this feature. I should think that you just match the voltage and current to the measure on the tester but the attempts I made were unsuccessful. Any advice?

author: Fluxia
author_rank: Contributor
timestamp: February 03, 2025, 02:02:28 pm
content: update: actually I found instruction on how to calibrate - see attachment . it works fine with the voltage (which however was only a few mV off) but does not appear to work with A, which is quite a lot off. .. it does not enter fase 02 when pressing the on button briefly after setting the correct Amp measure... (this does not happen when calibrating the voltage)

author: ledtester
author_rank: Super Contributor
timestamp: February 03, 2025, 02:31:41 pm
content: I'll be getting one in the next few weeks.I would test the converter with a simpler power supply -- any wall wart, or laptop brick power supply or even batteries -- and see if you still have the problem.

author: Fluxia
author_rank: Contributor
timestamp: February 05, 2025, 01:27:42 pm
content: Thanks for your reply. I have just removed it from the chassis and connected the output directly to the load, with ground not connected to the chassis/PSU ground and it seems to work well. Was I suppose to keep the buck-boost converter ground separated from the ground of the PSU? (Note that PSU ground is connected to earth).Anyway it seems to be working fine with the ground isolated from the PSU ground and if you are getting one soon i can tell you that I have tried other ones before this one, and this seems to be the best.

author: ledtester
author_rank: Super Contributor
timestamp: February 06, 2025, 12:52:08 am
content: Shooting from the hip here, but what if the converter looks like this:The resistor is the current sense, so if IN- and OUT- are connected you won't get an accurate current reading.Some things to test this idea:- Power the converter with an isolated supply (like batteries or a transformer based supply) and connect OUT- to earth ground.- Power the converter with an isolated supply and connect OUT- to IN- but not earth ground.

author: ledtester
author_rank: Super Contributor
timestamp: February 26, 2025, 03:41:18 pm
content: Mine just arrived after taking 16 days to get through customs.Is there a way to turn off the beeper?

author: bus_fan
author_rank: Newbie
timestamp: March 04, 2025, 10:03:10 am
content: Yes:Press and hold the SW button on the main interface for 2-3 seconds to enter the settings menu.The first parameter is the buzzer setting (bEP).Turn the knob to change the value.Press and hold SW again to leave the settings menu.

author: Fluxia
author_rank: Contributor
timestamp: March 24, 2025, 03:42:11 pm
content: Sorry for the late reply but I was on Holiday when I saw your message I forgot to reply when I came back. TBH I was not very keen to fiddle with this converter having damaged the previous ones and since it is now working as intended. How are you finding it with yours?