I just got a couple more of these in the mail yesterday. They are slightly different. If I get a chance I'll try to create a modified schematic on the latest one and add it to GitHub. The resistors are a bit different, and they have a programming port with 6+2 holes instead of 8+2. After quickly testing the pinout of the latest ones it looks like it is connected to the hardware SPI interface instead of the UART+SWIM pin like the one shown here. The latest ones I received have unmarked chips but the power, ground, Vcap pin, ADC inputs, and LED display are all connected just the same. There are a couple of odd smd resistor type mounting pads on the front side of the PCB just opposite to the microcontroller, and in the trace path of the programming port. I'm not sure what those were intended for, but they are unpopulated. The lowest 2 pins of the programming port are Regulated 3.3v Vcc for the chip (aka the linear regulator's output pin), and the other pin is ground. There is no connection for the voltage sense pin on this header, and the swim port is not connected (bummer). It looks like they also eliminated a couple of resistors by using 50k pots instead of 20k. The overall single side gain stage of an LM358 op amp is still used just the same.

Very grateful for the schematic, and appreciate the effort you've put in to trace the circuit out!

Just found your channel, such a great resource! Immediately subscribed, thank you!

Excellent work, very good video, it helped me a lot, the manuals, the detailed pins and lines; I am very grateful. Greetings from Colombia.

Thanks for the schematics! Just used this to convert a two wire 7-100v volt/ammeter into a three wire (disconnected the 270k resistor for the voltage input from the vcc input, so now it can measure down to 0 volts instead of dying at 6v :)

Thanks for your hard work friend. I am greatly helped by your work because it has answered my curiosity as mine has the main IC with no marking code at all. I really appreciate it.

what a lad, very nice of you to do the job the provider didn't. Very much appreciated!!!

Great article, thanks to it I can finally stop thinking about replacing the burnt STM8S103F3 with a new one, throw away the DSN-VC288 with a clear conscience and take care of something new :). Best wishes ! Marek

Lots of thanks for the schematics. Very helpfull to me. Awesome 👍

Excelente iniciativa, mis felicitaciones y agradecimiento por este importante aparte

Nice job! Many thanks.

VERY GOOD VIDEO, I SOLVED MY PROBLEM TO IDENTIFY A COMPONENT

Thanks a lot for this info. Ali forgot to put in the shunt, so I got some crazy Amp-values. An external shunt is obviously needed.

Thank you for well done Job!!

Wow! Great work and thank you so much. I need to improve the current calibration by changing the resistor values. Could not do it without your schematics. Thanks again!

I think its ironic that we are reverse engineering stuff made in China. I use these little guys on my CNC machine! Glad to have this info. Glad you did this work!

amazing , Very grateful for the schematic

I have replaced the 180k resistor from the closed loop of the op-amp with a 1k resistor. (this to reduce the gain and make the measurements less sensible to noise). And replaced 8k2 resistor from the inverting input to ground with a 100 ohm resistor (this to have more resolution from the shunt resistor). And added a 10nF from the output of op-amp to ground. Now is hard to calibrate with the 20k pot (i don't have another) but the ammeter is stable and precise. Thank you for the schematic. (The op-amp can drive 30mA so 100 ohm + 1k to ground is more then safe)

Thanks! very useful material :)

Great work, great resource, plus great music. A very worthwhile contribution appreciated by many. I am about to try to measure an active load a blocking diode should do the trick ( I hope).. Solar panel via a regulator to a 12v battery