I picture worth a 1000 words, Julian I watch you video ALL the time, many multiple. I wiring diagram of all this would REALLY help us understand your testing and how we could do the same to learn more. Thanks for all the efforts!

Great videos!!! I went on ebay to buy one amp and one volt meter and spent less than $4.50 US total including shipping. Can't wait to see how they work. I mainly build LED stuff so these should work fine for me. Thanks for the good work!!!

Wow, youre testing all the products I buy/want to buy from ebay. Thank you!

Could have wired a reliable DMM along with Amp meters for comparison and to be sure your output was not off at source.

Thnx for doing this vid! Bought an 10A ammeter from ebay a couple month ago with big blue digits. It was simply horrible. Under 300ma it under shot a huge amount and had an enormous overshoot when working at 1+ amps. I tried adjusting the pot and even cutting away some of the shunt and all it did is adjusted the offset but didn't help with the accuracy a bit. Ordered an open 5A meter and when it comes in a couple weeks ill compare the accuracy. The 5A meters use a 50mohm power resistor which seems more reliable than a piece of cheaply bent metal.

Excellent!!! Thank you for sharing. I'm looking into building a bench power supply for testing. I've been watching your vids for a bit now. Very informative. I like how you deliver your information.

Great video, the ammeters need a separate 12 Volts power supply. I have blown up two already ( my own fault ) simple wiring error. Also free P&P, can't go wrong.

eBay rocks. I have purchased a whole bunch of stuff very cheaply and the vast majority is well made and of relatively high quality, especially for the price. It make you wonder about the incredible markups we are faced with when buying local. I guess someone has to pay for the CEO's yacht

You can probably adjust the one with no pot by scoring a cut very gently with a file or knife blade (increase resistance) or apply solder to it along it's length length (decrease resistance) This will be a very tiny adjustment, well under 1 percent for adding solder and for cutting a notch it will depend on the depth of cut (be very, very gentle!) but is unlikely to be more than a few percent at most. At least you can solder over a notch to undo the damage or remove the solder with wick. We used to run a layer or solder over shunts then scrape or it off to trim them, before giving them a coat of shellac to protect them from the air. Make sure you clean off all flux and/or metal filings afterwards, filing is best done upside down to the filings fall away and not into the ammeter!

helpful, thanks. It would be nice to know how to wire up these amp readers.

Bought one of the dual Volts and Amps with a separate shunt to read Amps on a car amplifier set up in home, works with the shunt but it is meant to able to read under 10A without it though it just doesn't work without the shunt.

more digits (after the decimal) does not automatically mean more accuracy

I ordered a dual display from ebay. I don't expect it to be super accurate but a good indicator of how much power and voltage was being drawn from a supply. If you want accuracy get out your test meter ;)

Excellent and very informative review. I have just received a dual display volt and amp meter from eBay seller easbon in china. it has two connectors, a smaller two pin one (red and black wires presumably for the supply voltage?) and a larger three wire one (red, black and blue wires). I am not sure how to wire it up and don't want to fry it! I am only a novice in electronics. Could you please describe in detail how to connect it to my self built LM317 adjustable power supply.

Thanks for posting this. I've just received the dual Volts/Amps version and was wondering how to connect it to measure amps. Apart from the power supply leads there are 3 wires (red, black and yellow). The red and black are for measuring the voltage but where does the yellow one go?

I liked your video! Its quite easy to find a reasonable Ampmeter for DC but look for one for AC 0 - 50 Amps. I found one on ebay for 12 Eur that claimed to be very precise, but the deviation campared to my other DMM and Clampmeters is around 5 - 10 %. Would like you to make a test on these AC Ammeters :-) P.S.: i included 4 of those DC and AC Volt/Ammeters in my diy PowerSupply which is capable of providing up to 30 V at 30 A and 50 V AC + 70 V DC up to 20 A. It consists of a variac combined with two toroid-transformes delivering 4 x 12 V at 10 A each (I added another coil for having more Amps in lower voltage) and one 2 x 50V / 10 A which i connected in parallel. I added 2 bridge rectifier and 2 big caps for DC with low ripple. For the Power supply of the panel volt/ampmeters i added a small DC plugin PS. The funny and annoying thing with these chinese panelmeters is they influence each other when combined through the same power source and they even influence the DC output of my Power supply! They must be funny wired inside and probably dont like to be connected to the same power source. I blew up the internal caps of the auxilliary powersource for the panel meters, when turning on the DC output to more than 30 V. On the other hand, the aux. powersupply for the panels also raise the Voltage of the DC output of my Powersupply. Without all those panelmeters everything works fine - so there must be something strange with them. You can find the discussion and construction here in german language: forum.mosfetkiller.de/viewtopic.php?f=2&t=62975&sid=3abd7c35d8929bf181a8ee25bf111633 would like to hear your answer on that problem. cheers

Good review! For such precision questions its always good to have a really reliable accurate table volt/ampmeter to have a real reference. Otherwise its all guessing. But the fact that they all show similar values may lead (mislead?) to the idea that they all are nearly accurate enough for most purposes :-) These chinese panelmeters are a good value for the price anyway! I specially like the 4-digit volt + ampmeter for around 5 pounds - that is very precise up to the mA and mV.

Really useful review, thank you. Does the ammeter show -ve currents? I want something to measure the current going into or out of the leisure batteries on a motorhome

Jullian wire ! thick & thin, as you know there's a great range of wire gauges out there, no one every seems to give a ball park gauge when there demonstrating there gadgets, so what gauge are you using for this lot, 1 to 36 AWG or 0.19mm to 8.23mm SWG & thats just a few, not every one knows the voltage a wire can carry with out blow their gadget up or frying it. but as alway your informative Tutorials gems.

Thanks Julian I've just bought some of these.

I found the dual volt / ammeter to be junk. Its non linear so the pots on the back are useless. Adjust at high voltage or current and the low end is way off and vice versa.

thanks for the info !! so which one should i buy???

I want to separate the power source and the actual input pin so I can still run the voltmeter but measure down to 0 volts on the input. The way it is now the two inputs are tied together and when the power gets below 4 or 5 volts the display quits. Where can I separate these 2 inputs so I can measure down to 0 volts but still have the measuring part (LED's and measuring part) running from a separate 9 volt source?

i think they are very close to it depens of course if you need a very accurate reading ,but for example a rf amp they work 100 %. greeetzz: frankie

The dual V/A 3 digit model come with a FIXED single decimal digit on most of them. I have been tearing my hair out trying to find the much better floating 1 / 2 decimal V version, like the one you have. Please, please, what is the exact URL for the one you got???

It would be useful If you measure and share with us what is the voltage drop at 1A current.

Hello, how would you go about wiring the ebay red & blue panel meter so that with a 24 volt power source to be able to show the voltage from the 24 volt power source But also show the load from the same 24 volt battery?

@julian, Am trying to use one of these volt/ammeter live Diagram 2 in this pic : g02.a.alicdn.com/kf/HTB11puLIVXXXXbwapXXq6xXFXXXd/2in1-Volt-Amp-Meter-DC-0-100V-100A-Blue-Red-Led-Digital-Display-Voltmeter-Ammeter-DC.jpg But I have found when I take the input below 3v the display goes off, do you know of a batter way that I can get the screen to show the output volts and amps ?

the one thing I hate about the Digital Amp meter, like for with solar and you want to measure more than one current area of a circuit and you use a large blocking diode to isolate wind turbine readings from solar panels, to battery voltage current charging and then power out I can have up to 4 areas to measure at times. and I have found with current meters you need to have the grounds isolated. have any good ideas on a cheap Isolated power supply that can be used I like to just use my battery bank for power but cant do that with out a isolated power supply to isolate the grounds.

I am thinking of connecting one of the duel ammeter voltmeters to my motorcycle, to see voltage acrosi s the battery and total current drawn. I have the 50A one from the same seller, do need to install a seperate shunt?

I just got one in a kit from china. It has 3 digits and a polarity indicator. The kit was easy to assemble and worked the first time it was powered up. I have one issue with this as with the others like you are showing. They are not linear. As you increase the the current, the accuracy decreases. Compared with my HP3468A. If anyone knows how to modify these to have better linearity, please comment.

I thought it very interesting that someone would do this. You must be retired and looking for something to do. (Added note) Most of the cheap meters from Hong Kong or China don't provide any information about the voltage needed to power them. Has anyone seen such a meter that is powered by voltage other than the 9 V that Julian uses?

Hi Julian. I have been using some of these cheap volt meters. Have you noticed the input impedance is quite low around 100k compared with an actual DVM. Did you find a any good AC meters. Do you happen to know frequency they work up to. I'm looking at doing audio measurements.

Which model ZXY is that?I want one! I've never seen one with a pot knob.I HATE having the little screwdriver pots!

You can never ahve too many led volt meters.... don't let anyone tell you otherwise. :)

I would love to know how you wireded the setup?

Is there a way to mod the voltage meters to be powered separately (not powered by the same pin as they sense voltage on). I want to be able to insert them in a circuit without disturbing too much as well as being able to measure less than the minimum voltage of the microcontroller/led display.

I bought one of these combined voltage & current meters a while back which comes with two wires for powering leds and three wires (red, black and blue) for measuring current/voltage, however I couldn't find any diagrams showing the proper way to connect these. By the looks of it it has a shunt resistor. Btw, that power supply was nice. Can it regulate both voltage and current?

Hi can you tell me how to wire An Ammeter with out a Shunt to a solar panel thought controller or a set of batters Analogue and how do you test An Ammeter thanks

ohhh Nice Eneloops ya got there. :P

Great videos Julian and very informative. If building a PSU involving these meters, do they both have to have independent power to run properly. How would you avoid a short?

I woudn't say you display in the power supply is accurate either, you have to use a precision reference instrument to establish that.... So for layman work they are all accurate!...

What is that power supply

Great video keep up the good work

So, is it possible to hook up one of these LED voltmeter+ammeter things with just one power source? I'd like to install one for a linear regulated PSU, and two for a DC-DC boost converter to monitor SLA battery voltage and current, and converted voltage and current. Most diagrams show a separate isolated power connection to the voltmeter, while I would like to power both the voltmeter and ammeter from just one power source: 1. Power from linear PSU 2. Power from SLAB 3. Power from DC-DC boost converter Is that possible? I'm a bit confused by all of this...

Hi Julian have you details on where and much your buck converter thanks mike

Im looking to install one to my 250 amp engine driven welding machine. Would the combined volts and amps meter handle the load?

Hi i just got the same volt/ amp meter as you for my solar panel in order to be able to measure how much power its generating am i right in thinking its wired black to yellow i.e negative in as black and out through the yellow cable?

hi there is possible to test a car computer trip, off the car obviously? Cheers.

Thanks for sharing.

Is there a way to wire an ammeter into a switch to measure two different amperages? For example, switch one way to measure current from the solar panel, and another way to measure current to the load? I was thinking of using a 6 pole dpdt switch, but the problem is that the non-measuring circuit will be unhooked. Maybe two switches somehow? Any help appreciated.

Never mind, already found out how to :)

Ebay is very addicting I am doing exactly the same

Great info on amp meters. When you talk about price please also mention price in U.S. dollars. I do not understand the English pound system.

same buying spree for me in 2017. :-)

Thanks for sharing

ebay Sucks! or some of the sellers do. I just bought a Digital, 300 amp ammeter with a separate shunt , similar to the ones on your video but not the exactly same and the seller can't seem to send me the correct wiring diagram, with the same colored wires and he/she hasn't once mentioned a separate power supply, it's like they don't really know what they are selling. Previously bought a 300A (model name) digital meter (all in one) with two large + & - wires on each end and it started to melt at around 200 amps, although it did read it (197 Amps) but it couldn't handle it for a more than a minute or so. Some ebay sellers suck Bad!!! They must be Dumpster diving .

Thank you

Hi peeps,i have a very old but very good car battery charger with the old type analog ammeter ,what i want to do is re-case it and replace the ammeter with an ammeter/voltmeter like the ones tested,is this posible ?,the diagrams i have seen are for measuring a load and not a charge,do i just reverse the ammeter cables ?.cheers.John.

hi will this ok to use for powering 10w to 100w led chip and check all the led work okay please advice thank u

EBay links ?

What power supply is it

can i use any of these amp meters + a Shunt to measure the current draw of a computer Graphics card (aka GPU) ? I intend to place a shunt in between the 8 pin PCIE Power cable and the GPU PCIE connector. will use a PCIE 8 pin extension cable and joint all the negative black cable together and connect to the shunt. So, is there anything wrong in this setup? The gpu Draws around 23A max at@12DC

I didn't see you use one I the video but do I need a shunt? I will be pulling up to 9A on my meter.

Great tutorial thank you, but what does " shunt " mean please? :)

@ 2:43 I wonder how many viewers picked up their cell phone. :-)

What power supply are you using?

Hey guys, I was just curious, does anyone know how to build a custom analog/digital meter? I need to measure the readings digitally, but I need the analog needle present, to transfer that information..... and it needs to be really small, like 1/2" x 1/2" x 1/4" if anyone knows please message me ASAP please!!!!! I REALLY need help , thank you so much

Hallo Julian, Some Guys realy can ask stupid questions, can't believe it!!! Ok, back to the Theme! The open Frame Ampmeter you can adjust on the Backside were are the Pins locatet with "+" / "-" ! 1 Tip on GND and the other Tip on plus or minus, let the Display scoll up and down for adjusting

FYI, your buck converter has some fake panasonic capacitors!

Hi Julian. You are over paying for all the electronics you buy on ebay all of them are dropshippers. Why not just buy from aliexpress directly for much better prices?

link for your power supply?

Hi Julian Ilett, I have the same as the second ones from the left that you review. However when playing with it, by accident I have made it not working properly for the current meter function. I don't know how to fix, and what wrong have I done to made it like that. Could you be able to have a look at my post in EEVBlog forum, and help me to fix it please. Link: www.eevblog.com/forum/beginners/(repair)-current-reading-error-with-dsn-vc288-(100v-10a-voltmeter-ammeter)/ Thank you so much.

cable's impedance, temperature, humidity, electromagmetic fields - can make the ammeters seem unreliable.

why do they ALL have LED screens and not LCD screens?????

where's the load

this one is reading point nine nine nine nine nine nine nine nine nine 7 and this one is reading point nine nine nine nine nine nine nine nine nine 8 Volts

Worthless without knowing what the actual value is, all you did was rely on another digital display meter slapped onto the power supply.

I didn't see you use one I the video but do I need a shunt? I will be pulling up to 9A on my meter.

why do they ALL have LED screens and not LCD screens?????