The SOT23-6 device is a MCP3421 18bit ADC

Nice hack. Love how a simple pinch can make these more accurate too. Great video.

Well done, Peter; nice hack. I'm impressed with how accurate that meter turned out to be. I'll have to buy one and fiddle around with it myself. / On another topic, I wanted to thank you for the videos about building your workbench. I copied your design and now have a very sturdy 3' x 8' bench with shelves above and below. Lots of space to build stuff! Cheers.

Thanks for the explanation on how to measure the current differential. I am in the proces of building a dual powersupply for a testrig for eurorack synthesizer units and now I think I can build it the proper way 😀👍🏻

Nice job, Peter. Thanks for the video.

That little "display meter" is more accurate and precise than most handheld DMMs on the market.

I have finaly found a instructional video on this specific topic, that is spot on how to understand the princible of this kind of meter. You have earn my subscipsion to your channel 💪.

Nice hack. After watching it I ordered a few of these units too to replace the analog indicators in my bench supplies. I must say though that in the last part of your presentation, where you discuss the DC-load, you seem to become a bit sloppy and rather brief in explaining things. I fear that a number of interested viewers can't follow that anymore. Just dropping a simplified schematic without further explanation about the basic workings of the DC-load probably leaves a lot of viewers puzzled (as I was before a second view of that part). Anyway, I appreciate your effort to spread knowledge about electronics. People do not seem to realize anymore that that (and other technologies too) have become basic necessities in our present world. To some of the other commenters I'd like to say: try searching and tinkering a few minutes longer.... I did find identical panel meters within 2 minutes (even at a better price), so don't bug Peter with silly questions and appreciate that he sparked your interest. The fun of electronics as a hobby is finding out things yourself isn't it?

Good tips!! thanks for sharing.... and 2 thumbs up for the great presentation!! :)

Great hack. Nice video

Great little hack Peter, well spotted. I wonder if a similar mod could be made with their higher current versions? Looking for just such a meter right now.

Brilliant - thanks Peter - a great and useful hack and extremely well presented. I picked up one of these "ebay" panel meters which has exactly the same wiring configuration but only 3 digits... I wanted to do your differential hack which will be perfect for a project I'm working on but unfortunately the I can't locate the 0 ohm surface mnt resistor... - ie. the circuit brd has a very different layout... I tried to find the actual module you used but the links are no longer active - so can you; - help me figure out where the 0 ohm is on my unit (I could send you a close up photo of the board or - tell me how/where I can buy the same unit that you used / hacked... Many thanks

Just what I needed, thanks.

Did you take any data to show the difference between before and after the hack?

It's been 8 years on since this video was uploaded. None of the wise guys in the electronics world who have seen this and commented here till today has pointed out a mistake made while measuring resistance in the milli-ohm range.............Our Great Guy here is A Shunt to the actual resistance being measured , because his finger tilps are in contact with both prongs of the multimeter. !!!! So much for the electronic buffs here !

Nice. Thanks Peter. Why do you not have more views/subscribers???

what about the high current ones? with external shunt. for like 500amps. I need one. but would like to know more about them before I buy one. for my 24v 5kw inverter plus multiple DC loads. so I can read total draw from the bank. great and informative video.

Excellent contents!!

I love these dual volt/amp meter modules - but have always run into the limitation for its application due to the common ground between the volt measure leads and current sense leads. This modification is great !! I just wonder why the manufacturers don't manufacturer the module with the current sense floating in the first place??

If I do this hack can I use different Gnd or - for meter pwr and Amp circuit? I believe the - blk small wire and - blk large wires are same potential.

Nice vid! I presume both segment displays are identical ? but as Im waiting for my delivery I wondered if there is a simple hack to reverse the colors because Im more naturally inclined for Amps to be red and Volts blue or is it simply desoldering both segments and swapping them around for the color change?

I was excited by this hack and did some testing and promptly burned out a meter. Reading the ADC data sheet, we see that the inputs can't exceed VDD, so that might be it. In any case, it ruins my use case. My use case: a 5V and 12V supply. Low side current monitoring won't work as electrons won't know which path to take. Does anyone know of a high side solution/suggestion?

Thanks for the Link eccentric, When I looked, searching CA2P nothing came up :( so I appreciate you sharing and yes it looks exactly like the one I was observing, now I have the info, perhaps I will hook up my I2C protocol analyzer and see what its doing with it. It looks like a good chip to use in small projects and is probably very cheap to be included in a product like this

Cool dude ; ) I bought a digital ammeter 3 wire job , unfortunately I need a 'isolated' power for the screen display , or it reads the volts then adds the amps to that :/ the whole idea of using it was to ditch the battery . Maybe I can check the black wires like you did ; ) Do you think maybe a simple circuit could fix this problem in order to power the display from the source that is being measured ?

What MOSFET and operational integrator you use to do so? thanks for the video it's really clear information

I just go t one of these in the past few days for a similar purpose but it has an external shunt and I am getting some weird readings. If I connect the voltage wires (red & black) to 5v and connect nothing else, I get a reading of about 0. 56 A and no voltage reading. I'm thinking it is a dud

I have been trying to find the schematic for this because I have a blown SMT resistor next to the small connector and I can't read the value

DSN-VC288, however, my example has no internal shunt... In lieu of the shunt, a R075 SMD.. also Versions I have (with Shunt) do not have "CAP" device nor 0 Resistor... Also have seen 2 solder holes upper-left while looking at the back, shorted together at turn on, "resets".

A version of this with hall effect current sensor would be cool

Thanks for this smart dual display hack your diagram can the A meter also be placed between drain and + without damaging the meter special at higher Voltages ?

After seeing this video I ordered myself one of these modules in the hope to be able to modify it. Unfortunately it is a different layout. Besides an anonymous 20 pin µC it consists of an LM358 an M5333B (probably voltage regulator) and a tiny tiny 6 pin SMD marked with 3157 (ADC?). No quick win ...

Can it be hacked to take the amp reading from the + rail instead of the - Rail? If not what volt/amp meter will allow me to read the amps from the possative rails?

Sbas 357 cheapy ti differential spi d2a?

Thanks for the video. What is the minimum current resolution? Can it read 1-10 mA? Thanks.

Hello, how have I just purchased an HP 3468A multimeter, and it is somewhat out of calibration as it happens with all these models, it requires calibration since over time the battery with which they retain their parameters is discharged because it is digital, however doing tests Simple it shows that if it reads voltages almost equal to those obtained with a cheap multimeter or perhaps better, but I am interested in tuning it, it has some video on this for repair, maintenance and calibration

Found this while looking for circuit and wiring diagrams for these meters. I want to separate the unit power from the sense because the all seem to be common positive and have the shunt on the negative. I am installing in a vehicle so I wish to keep common ground... Not possible in the normal state. I have 2 more recent versions that don't seem to have a 0R that I can remove. They also have a small wire 2 pin connector and a larger wire 3 pin connector, so they are arse about a bit. What else can I look for to allow me to make common ground?

tried doing this hack to a couple meters that are very similar to yours. only had to scratch a trace. however hooking it up, my current (blue) shows '----' meter still works but i think the ground side of the current meter also needs to be referenced from the meter. looks like the 'ca2p' isnt grounded anymore. I was trying to measure volt/current on battery and solar system, but not very successful. 1. plugged red/black to both meters from battery side. meters power, but no longer getting data. shows '----' on current side (blue) 2. plugged in current where one side is grounded. meter shows current (blue) Still working on it.

thanks bro I need to do this Cus I just got a dc one 0-99v and 0-50amp but its counting down from 50amp lol but I've got 12v bat powering it and it's measuring my li ion at 52v ish lol

Thank you very much for this vídeo.

Does anyone have experience of these digital meters in an RF environment? e.g. when monitoring voltage and current applied to a 10watt amateur radio transceiver?

I would like to use one of thease (I have the 10A ones) on a meanwell type 30A PSU. The PSU already has 3 shunt resistors going to the output of the PSU. Couild I remove the shunt from the meter and connect via some wires to the shunts already on the PSU Boared output for a upto 30A reading oin the meter?

Peter sorry for my questions and this.will be the last !!..it is not 10mah bit 10A .. the bike has a hub brushless motor and at least 15A i expect to flow and wantwd to measure without the need to carri a bulki shunt (i barely know what it is) in the bike while I ride...i bought 8 units and what i wanted to know if i use below 10A (not riding fast.or in big slopes) will i be able to have proper readings of amps lets say +/- 200mah error using stock.hardware? (no shunt is coming on that dx sku)

The little sot23-6 ic is a mcp3421 from microchip

sorry i would like to know what to do to have a 0 to 15A current range reading ok? i have just bought 8 units@!!

I got 2 of these think the pot on the back for adjusting currant reading is bad. any idea the resistance of the pot is. think I should be able to solder in a replacement.

Excellent video. Great Analysis and explanation. Do you have an idea of how to read AC 100A meter down to a mA. It is AC V/A meter model YB4835VA. I tried running several turns of the primary wire through it but got accuracy within 100mA. Many thanks V

Hello Peter Great video! I have the same meter, but i can only measure the current from the DC load negative terminal... Will this hack help me to measure the current from the positive terminal? If not you know how i can do it? Thanks

What is that 2 channel scope on shelf 2? I want it.

Only glitch, if the inputs go directly to the chip, they're unlikely to work below ground or above Vcc, a silicon limit as you would be back-biasing the substrate or tub diodes.

Great Sir 👌👍

Hi where dld YOU bougt this voltmeter

Nice. Thanks. Sorry to bother you, but I can't find a panel meter like your's. The one that you specify is only a 3A on max scale. Where can I find one?

Hi. I bought one of these volt\ammeters. I has a voltage adjustment pot, but no amperage adjustment, although in the description it said it had both and it even had pictures of the PCB showing both pots. Ironically, the voltage measurement is quite accurate but no the current. Is there any way I can increase the accuracy of the ammeter?

I'm obviously no electrical genius. Doesn't it just make sense that a zero ohm resistor shouldn't exist on anything? If its zero ohms then there's no resistance? That must not be correct.. I am a tinkerer.. Electric bike builder.. This guys stuff is always A++.. He's a great teacher, I'm the poor learner

I'm a beginner and I want to build a power source! Can you send me a wiring diagram? Thanks!

What is the voltage range that can power this thing? (what Vcc does it require)?

ok i have no shunt at all....should i use to measure 0 to 10A with no troble?

in the last 4-5 minutes you explain where you put the components in schematic form (very well i might add). i am having difficulty with practical application (putting schematic to real life components). i am new to this but could follow...kinda :-/ . Could you possibly break it down with actual components? I am very visual, and although your schematics are well put together, it still looks like a rat maze to me. i apologize for my ignorance. if need be i can give you a rough idea of what components i am working with. also, i am a little confused about the wiring on my unit. wire coloring is different. power to display is easy enough (red/black), but the shunt and test wires are confusing me. i have blue (pos to shunt i think), green (neg to shunt or test) and yellow as test positive..i think. their order of colors from power to test side are: black, red=power; blue, skip slot, green, yellow. i know without looking at circuitry it might be difficult to give me the answer to this, but maybe you can hypothesize from your/other units.

Question. Does it make a difference if they're 25mAh shunts vs 75mAh shunts or are they interchangeable?

Can someone update this showing how to hack the new dual digital so the negatives are not common?

looking for a meter that would differentiate between positive and negative current and give you indicators.

My model is unfortunately different. For the current sensor, it uses an op-amp (fed by 3.3V) configured as a single ended amplifier so with one side of the shunt connected to the V+ side of the op-amp (via R1) and the other side connected to the common PCB ground (so no magic zero ohm resistor in my case). The V- side of the op amp is connected to the PCB ground via a resistor (R2) and to the output of the amplifier via a third resistance (R3) that provides the negative feedback. For some reason that I do not understand (probably to compensate the offset) , V+ is also connected to +VCC of the op-amp (so 3.3V) via R4 which is actually very high (3.3 M ohms). My question is how to modify the operational amplifier set-up to switch from a single ended mode of operation to a fully differential one. The objective is to have the possibility to connect one side of the shunt to the + side of any external power sources whatever its voltage is (even if is > 3.3V) and the other side of the shunt to the positive side of the Load (the negative side of the Load being tied to the negative side of the external power source). I tried a few mods without success as the op-amp went into saturation systematically (even when the op-amp was fed by the same power source than the load so it shared the same +VCC). Thanks for your advises

First of all - great job and video, thank you for this. Now for a remark : wouldn't this hack also fix the biggest con with these, ie, that these meters can only work wired as low side current meter? Wouldn't your hack enable you to use it on the high side now as well?...

what's solution 20amp current measure using this ckt

THANKS

Both sides of the sense resistor must be “close” to GND. They can not be below GND, nor can they both be much above ground. Ask me how I know.....

DSN-VC288? (i.e. WHICH chinese "e-bay special" ??) searched for YB5135D...

$1000 DVM... wow.... came across similar "E-bay specials": DSN-VC288; two variants: 10A version where wire shunt is visible, 1A version (R075 SMD, in lieu of shunt)... wanted to use this to create low resistance test box (+/- 3.7xx Ohm and +/- 0.7xx Ohm), utilizing LM317 as current regulator... via 12.5 ohm in "adjust" circuit, set to 100mA... do the math... viola! Was trying to figure out if thin yellow current sense connects to "VCC IN" @ LM317... or "output" @ LM317... 5VDC "wall wart" for meter power (thin Black, thin Red). At $10 bucks a pop, trying not to roach too many.. also something similar with 10A version of DSN-VC288 and LM338. test box is for checking motorcycle wiring (over switches) and generator field/stator windings.

For those looking for an equivilent of the one I hacked, I found one, a company interesed in me reviewing some of this products sent me a display module among several other products and it is exactly what you need www.gearbest.com/development-boards/pp_134241.html, it says 3Amps but will go over 5, just the shunt gets a little warm which is probably why my origional once dissapeared from the listings and the all now say 3A.

Does anybody know if this is hack is also working with a DSN-VC288?

Hi mine did not come with a shunt. Does it need a particular value?

Now if anyone knows how to measure high side current white these meter?

shame ok...i wanted to use it for an ebike while riding...i think at least 15A would be a must.....thks

Nice hack, too bad these ebay meters all use these crappy blocky led segments

Sorry, starting with your diagram, I got lost. My dual meter is not exactly like yours anyway. More important how many folks will feel comfortable removing the minute resistor? I clear connection (hook up) diagram would of great help. Your verbal descriptions are not suitable.

i need your help regarding digital meter please reply or give me your email

Just what I needed, thanks.