Scullcom Hobby Electronics #43 - Milliohm Meter Update

[@alien8r33d]

It's great to see someone on KZbin producing constructional projects as opposed to all the teardown videos that the majority of KZbinrs seem to produce, and some very useful projects to boot. Big thumbs up from me.

[@scullcomhobbyelectronics1702]

Thanks Mike your comments are much appreciated. I do also a few teardowns but try to focus most of my videos when I can on projects for the hobbyist. Regards, Louis

[@edgarskarklins3572]

Teardowns and many projects where you just slam together cheap but low quality Chinese modules. Thank you very much for designing and sharing a practical quality little device. And the ducational value of the design proces is priceless.

[@IanScottJohnston]

Lovely meter, perfect for the workbench.

[@scullcomhobbyelectronics1702]

Thanks Ian. OSH Park produce some nice PCB's but the only drawback is that you have to order 3 at a time.

[@brucewoods9377]

Simply briliant. Love the new case design and the pcb. I am intending to build this soon.

[@scullcomhobbyelectronics1702]

Thanks. Have fun.

[@aklankrisz]

I have not built it yet, but this is still the most accurate DIY circuit. I think this circuit can currently measure 8-9 Ohms without any modification, but the display in use goes to "HHHHH" above 2Volts (2Ohms). There are already high-resolution 33V panel meter displays that also switch range below 10 volts, but they are smaller in size than the one used here. The INA106U IC can be powered from +/-18V maximum, it would be more useful to power it from +/-15V to be able to measure the full 10Ohm range, but I couldn't find such a charge pump in IC, only as a separate small PCB.

[@SatyajitRoy2048]

Double thumbs up for your wonderful work. Hope you are doing well. Not seen any new videos in recent days.

[@benoySimon]

Brilliant, very good presentation and brilliant ideas. Thanks for your nice update. A great encouragement for hobbyists.❤

[@MarkGarth]

Excellent work and very interesting, this is now on my 'to do' list. Thanks for all of the information.

[@scullcomhobbyelectronics1702]

Thanks Mark. Good luck with the build.

[@abeleski]

I have recently come across your channel and love it. Love it for the completeness of it. I am yet to build anything but this will be the first one. Ordering parts next week. Thanks and keep up the good work.

[@scullcomhobbyelectronics1702]

Thanks for your comments. Hope you enjoy building this project. Regards, Louis

[@jeffsansoterra7743]

I just finished building my unit using your design and the PCBs from OSH Park. Works really well! Thanks for the video!

[@scullcomhobbyelectronics1702]

Glad to hear your build went well.

[@nekelly123]

Interesting project and thanks for the information. I think I'll build this one and try using it to locate short circuits.

[@dhanursharma1752]

very much inspiring... I learnt how important it is for the end product to be presentable and user friendly from this project and I will definitely try doing this one! thank you so much Sir.

[@scullcomhobbyelectronics1702]

Glad to hear you found it helpful.

[@zikermu]

An improvement in the Milliohm meter. Better and Better. Congratulations

[@Scorpio722]

Incredible review and explaination, excellent process. It is great that you update your projects too. You are like one of the prior greats in electronics, very neat and professional presentations, excellent documentation, great responses to your commenters, sort of Forest Mims.

[@michaelstothard]

Thanks for the detailed video. I have just finished building it and it works well. Very impressed, thanks again.

[@scullcomhobbyelectronics1702]

Thanks Michael. Glad to hear it went well. Regards, Louis

[@stevieboi61]

Well explained! i hav no experience but you presented easy learning of this projects goal, components + where they go and what they do in the circuit! thankyou for sharing.

[@rodneyjaygarrett]

thanks for making these videos. I love them. I watch them repeatedly. Can you do a video on making a constant current dc load that a hobbyist could make to test home built power supplies. and maybe use it to drain batteries. Maybe 0-30 volt DC and 0-3 amp? Again Thank you for making these videos .I learn so much from you because you explain (very well I might add )the concepts and exactly how the components work. Your words are thought out well .You keep it concise without gibberish. Also a video on you would be nice to . Tell us about you background how you got started in electronics . Maybe a "show and tell of your lab" and all the instruments people might enjoy that too. Thanks again Rodney USA

[@scullcomhobbyelectronics1702]

Thanks Rodney. I will consider a Constant Current DC Load for a future project.

[@zikermu]

It 's really interesting to follow yours profesionnal explanations . Thanks a lot

[@chriscorcoran6889]

Just finished it and its working fine. I ordered the 1.4 boards by mistake but implemented the 1.5 changes. Geting hold of the 2V voltmeter (YB514B) was difficult to find in the UK. I could only get 200mV version. After a lot of mucking about you have to remove 2 resistors, RA and R1, the put a 100k at R1 and a 11K at R2. Then change the decimal point link to 2V. It should be 10K at R2 but I couldn't get the bourn pot to set it to 1.999 Volts. China seems to have a lot of 200V versions, suspect they could be modified the same way) I have 2 boards and 2 modified Voltmeters if anyone in the UK wants to have ago. (I also changed the 5V voltage regulator because the one specified seems to be either discontinued or a very long wait)

[@sh-hq9yk]

Hi, having the same problem finding the LED meter. Which ones did you buy and mod ?

[@audiotecnologia4084]

Their designs are always perfect , eager to see the next video .

[@scullcomhobbyelectronics1702]

Thanks. I am just finishing an update on my Millivolt Meter project and hope to upload the video soon.

[@pagepro211]

Great work! exactly what I was looking for, even the 1st one was good.

[@MarcoFranceschini1971]

Another great project...thanks Louis.

[@scullcomhobbyelectronics1702]

Thanks Marco.

[@PapasDino]

Good to have you back Louis!

[@scullcomhobbyelectronics1702]

Thanks Dino. I have been busy of late with having new gas central heating installed in the house which involved me doing a lot of work making access for pipes under floors and then putting some new wood flooring down. Also my youngest son moved in to a new build house and we had a lot of work there. Just about getting on top of all that now but still have to finish laying a new oak wood floor in the hallway. But I still love to get back to electronics in my spare time!

[@javierpallalorden]

A very nice update video, thank you!

[@scullcomhobbyelectronics1702]

Thanks.

[@PelDaddy]

Good to see you back on KZbin. Thanks for all the great videos. Thanks.

[@scullcomhobbyelectronics1702]

Thanks for your kind comment. I have been very busy just lately with work on the house and also work on my son's new house he has moved in to. Seems there is just not enough hours in the day to do all I would like to do. Trying to put a few more videos together as time allows me.

[@robertcalkjr.8325]

Thanks Louis. Nice upgrades.

[@scullcomhobbyelectronics1702]

Thanks, Robert.

[@FixDaily]

Hi sir, could you explain why you have used 4 resistors in paralel instead of 2 or just 1? Maybe to get a more accurate equivalent value and also to avoid thermal variances?

[@BajatecnologiaNetdiy]

Nice to see you back! Neat upgrade, thanks for sharing.

[@scullcomhobbyelectronics1702]

Thanks.

[@felixcat4346]

Very nice video. This device has many useful applications.

[@scullcomhobbyelectronics1702]

Thanks.

[@isidoromaich7226]

Thank you! I'm always waiting your new videos

[@scullcomhobbyelectronics1702]

Thanks, nice to hear.

[@voltlog]

Much neater than the previous version and I like the tshirt!

[@scullcomhobbyelectronics1702]

Thanks. My youngest son David designed the T-Shirt, may ask him to do some more designs :)

[@agaelema]

Very nice project. Thank you for share with us.

[@scullcomhobbyelectronics1702]

Thanks. Your welcome.

[@boogerhead0]

I am making a minor modification to clamp the voltage to 1.0V using ADR510 1v ref. My reason is that I plan on using this instrument to help locate power plane shorts on laptop motherboards. Since laptop VCORE is often 1v, I prefer to not approach 1.25 of original design. I changed the resistors to 4 x 44.2 ohms with the one above the pot to 56.2 ohms, and keeping the 100 ohm pot, providing a 10 ohm network, leaving the current as originally shown 100mA.

[@trevorcoard8777]

PDF Print Scaling issue. It appears that all your PDF files are produced with the "Print Scaling" setting set to 97% as the default. In Adobe Reader Pro, I have found that this needs to be reset (from 97%) to "None" (100%) to print at the correct size. I have noticed this on other project PDFs, for example, DC Electronic Load which also has the default Print Scaling set to 97%. Generally speaking, this setting is normally always left at the default setting of 100% when creating the PDF file, therefore requiring no further adjustments necessary to print out the exact size on paper. I am not sure which method you use for producing PDFs, but it seems that the default Print Scaling is always set to 97% during it's creation! May be worth taking a look at the PDF creation settings? These are exceptionally good quality videos and I applaud you for all the thought and effort that you put into these. I look forward to more projects from you in the future.

[@scullcomhobbyelectronics1702]

Thanks Trevor for your comments. Yes I am aware of this issue. I found that if you save the PDF file to your PC first then open with your PDF reader software it works OK. The problem is that when you open up the PDF file in the internet browser it opens at reduced size (97% as you say). You can make some setting changes in the browser to correct for this but I think they do it so the PDF is sized to fit the screen. Just lately I have been supplying all my PCB artwork as ZIP files and when you then unzip and open the PDF file its OK. You also need to ensure that when you print in the print setting make sure you select print "Actual Size" and not "Fit" (for some reason it may select "Fit to page" by default in which case it will print at 97%). Regards, Louis

[@francofranceschini9591]

Great T-Shirt Louis...great...

[@gregory6488]

A comparisson between the two different versions would have been great.

[@irgski]

Not sure if this was suggested but, if you add a switch and a resistor, you could use the internal voltmeter to calibrate the 100mA source, thus not requiring the external DVM.

[@scullcomhobbyelectronics1702]

Thanks for the comment. Nice idea. Regards, Louis

[@shlomsi2000]

Excellent design and a useful meter. I just want to suggest a little improvement: As all resistors but the trimmer are 15ppm/c and the trimmer is 100ppm/c, it would be better to choose a low as possible value for it and still have enough room to compensate for the 0.1% tolerance of the other resistors. A value of 10ohm will be a good choice as it will greatly reduce the overall temperature coefficient of the whole array and also reduce drift due to vibrations. Of course the 63.4ohm will have to be changed to a higher value to complement it.

[@scullcomhobbyelectronics1702]

Thanks for the comment and suggestion. Lowering the value of the preset to 10 ohm is a nice idea, in which case the 63.4 ohm would be replaced with a 102 ohm (nearest available value at ±0.1% and 15ppm). Would then need to check if there is enough adjustment for calibration. Regards, Louis

[@zebratangozebra]

Nice thing about a meter like this is if it breaks you can fix it yourself.

[@hullinstruments]

Beautiful build! would it be possible to add a small circuit for generating a variable tone? A tone which would go up and down depending on resistance. So that low resistance is a very deep tone, and the pitch gets higher as the resistance gets lower. So as you get closer to the short on a circuit board… The pitch becomes higher. similar to the “tone-ohm” device sold by Polar Instruments. Thank you for your input!

[@fredlllll]

you could make a git repository with the design files. helps you to track the versions and people can maybe make suggestions

[@scullcomhobbyelectronics1702]

Thanks for the comment and info. Not familiar with GIT but worth looking at.

[@fredlllll]

there is a program called sourcetree which is a complete git client with GUI. dont have to fiddle with the command line. i use it for all my repositories :D

[@AndrewGillard]

@@fredlllll As a quick update to this: I got fed up with Sourcetree after they updated the design, introducing a ton of bugs and stability issues, and then seemed to ignore it for ages =/ I'm now using GitKraken, which I think is much better, and faster (my main gripe is that it can't open more than one repository at once, which probably isn't a concern for people who don't use git very much, but is more of an annoyance for me as I often need multiple repositories open simultaneously for work - and even more so when I use git repos for tracking my KiCad PCB-design projects...). It's also free for personal, non-commercial use (though I have to pay their $49/yr as I use it at work and for occasional consultancy work, too) :)

[@fredlllll]

@@AndrewGillard yeah its pretty buggy but my computer cant handle running another electron app. Also gitkraken crashed just as much on me as sourcetree currently does

[@AndrewGillard]

​@@fredlllll Interesting that GitKraken crashed a lot for you. I'm not sure I've ever had it crash for me - but then different hardware & software combinations can often cause issues like that, so it's not too surprising! (I'm *so* glad that I don't generally write software that gets distributed to lots of end users who I have to support using it on and endless range of hardware/software combinations!! I'm only doing Web development these days, and I don't think I've ever had to write anything of any complexity that would be running anywhere but my own/my employer's own server(s)!) If it wasn't for you saying that you can't handle running another Electron app, I'd ask if you've tried it more recently, as the stability issues might have only been in the past. But yes, if your PC is already at its limits [*glares at his Surface Pro 3 with its pathetic 8GB of RAM...*], another Electron app may not be a great idea ;)

[@markj3851]

Louis and All- Another great video and project that I'm excited to make. The e-bay links in the parts list for the 4.5 digit high precision panel display are expired and I can't seem to find anything similar. Are there other vendors that may have something similar?

[@BillKukowski]

if you build this, note the BOM lists an incorrect part for R10. It should be 499K ohm not 499 ohm. This is per the schematic and the ina106 datasheet application note. This is an acceptable part for R10. www.digikey.com/product-detail/en/te-connectivity-passive-product/YR1B499KCC/A105891CT-ND/

[@scullcomhobbyelectronics1702]

Thanks Bill for pointing out the error. I think it was finger trouble on my part while typing :)

[@markbell9742]

Thanks Professor. Cheers, Mark

[@scullcomhobbyelectronics1702]

Thanks

[@rogeronslow1498]

No problem finding those hairline shorts on a new PC board now.

[@scullcomhobbyelectronics1702]

;-) Regards, Louis

[@zx8401ztv]

Smashing job sir :-D, slimmer and neater than the original, and still a very accurate tool. :-). That pcb is so neat, he did a good job didnt he :-D. Extra capacitors, catching the high frequency noise i guess, i still dont get the oddness that high value capacitors dont catch everything, but its known so a smattering of different value capacitors around linear regulators is stamped into my grey matter LOL :-D. Hey dont forget that youtube is a hobby, we dont expect you to churn out loads of videos, you have allready produced so many excellent tutorials/projects/teardowns :-D.

[@scullcomhobbyelectronics1702]

Thanks for your comment, always welcome. The reason the larger electrolytic capacitors do not filter everything effectively is due to the fact of the internal inductance. You will often see several different value capacitors in parallel so as to prove improved filtering over a wider frequency range.

[@zx8401ztv]

You know what, i think my brain is wiping info without me knowing, I should have remembered inductance, im putting the "D" cone on and standing in the corner LOL :-D

[@scullcomhobbyelectronics1702]

Just SMILE !!!!!

[@Barbouri]

Louis, really enjoyed the project update, and especially the innovative use of the PDF drilling template. There is now an updated version 1.5 board available with only a few minor hardware changes such as a PTC fuse, larger capacitors in the charge pump circuit, and a 5 volt supply header for the panel meter. www.barbouri.com/2016/10/09/milliohm-meter-version-1-5/ Thanks again for the educational video's.

[@scullcomhobbyelectronics1702]

Hi Greg, Thanks for your comments and info on the updated PCB (version 1.5), details of which I will add to my website on this project. It is also nice to have a 5v supply header on the PCB for the panel meter. Thanks for all your work on the PCB, and for making it available for other hobbyists, making the build of this project much easier. I hope to also upload an update video on the Millivolt Meter project soon, using your PCB. I particularly like the use of guarding on the PCB around the input area - signs of a very well designed PCB - great job. Thanks again for your support, it is most welcome. Regards, Louis

[@fizzyade]

Fantastic video and description. I’m wondering why you went completely analogue and not down the digital route since it offsets and adjustments could be compensated for digitally. I guess part of the answer is that you’re “doing it right”. I’ve just completed my own design and I’m really curious to see how mine performs against yours, since mine is a lot simpler! (And probably a lot less accurate)

[@gtag174]

Just assembled your design on the pcb and the meter reads -0.002 tried adjusting R12 but the display don’t seem to be responding. I heard a crackling sound earlier while soldering when the solder leads had to her some part of the pcb so I guess I may damages some IC but not sure which one.

[@LaLaLand.Germany]

What a lovely piece of kit! I love the case! But there might be problems getting it since a lot of British sellers don´t ship to Germany anymore. I understand why but it´s a crying shame that all of that went down. Do You ship to Germany? I think I´d like to get the kit to assemble myself, how much would it be, compared to a readymade solution? Kind Regards

[@passioneelettronica]

Hi, I like new version, but why don't you use multiturn potentiometers with knobs instead of trimmers?

[@audiotecnologia4084]

Hugs from Brazil.

[@scullcomhobbyelectronics1702]

Thank you.

[@gtag174]

Seemed that the meter connections were wrong. Corrected it and now it shows 0.0000. I read a voltage 19.19v at the opamp and at pins 4 and 8 on the charge pump IC. is that normal ?

[@eZinovate]

Great design, would it be able to connect this to the milliohm meter with Arduino nano in your other project.?

[@scullcomhobbyelectronics1702]

Thanks. Yes you could connect it to the Millivolt Meter project.

[@satishkumar-gg5fm]

i want this full assemble circuit....where i can purchase this

[@davidgorringe]

Can I swap farnell No.9725717 not found on their website for farnell No. 2519475 as a replacement please

[@scullcomhobbyelectronics1702]

The Farnell part No. 2519475 is OK. For some reason Farnell changed their part number.

[@SuspiciousPixels]

Is this still the best DIY milliohm meter as the video is 7 years old

[@ibringthelastwords1358]

I want to build one to test some batteries but the ICs are hard to find now 😓

[@carcarrcracing8944]

If I were to build this, would it provide results comparable to the RS components 611-953 meter? Rhopoint, Model A210-091 Ohm Meter, Maximum Resistance Measurement 200 Ω, Resistance Measurement Resolution 100μΩ I am interested to know if building this would be cost effective as well. Gordon

[@miguelsl5417]

Hello. Very very nice job. Is possible measurements up to 9.9 Ohm? (Only change digital panel 4-1/2 (2V ) for digital panel 5 digit (10V)) I have a problem, OSH Park not sent to Spain. Thank you.

[@scullcomhobbyelectronics1702]

Thanks. You should be able to read up to 9.9 ohm using a 5 digit meter. You can check that by using a multimeter to measure the output voltage. OSH Park manufactured in the USA, but they do shipped for free to anywhere in the world. Checkout their website: oshpark.com/ You can also download the PCB artwork file free of charge from OSH Park. Alternatively checkout the first video I did on this project where I give details of a simple PCB. Link below: kzbin.info/www/bejne/l5-oYZ16mqeortE

[@miguelsl5417]

Thank you. OSH unavailable shipping to Spain. I am making PCB (#31). What is the maximum measurable resistence? - 20ohm (for input voltage INA106U +- 10V) Thank you

[@acharfarance5835]

brilliant!

[@scullcomhobbyelectronics1702]

Thanks.

[@diyiqos7729]

I would like to get one of this meter is that position to purchase?

[@year2525dpm]

¡Genial!

[@davidhenrycat]

Please help Farnell part No. 9725717 not found. Can i use Farnell part No. 2519475 in its place.this is going to be my first project.many thanks.

[@scullcomhobbyelectronics1702]

The Farnell part No. 2519475 is OK. For some reason Farnell changed their part number.

[@xaviero1412]

very nice meter sir. Can it be measuring onboard component ? Thanks

[@scullcomhobbyelectronics1702]

Thanks. You could measure on-board components as long as power is removed. Could be useful for identifying where shorts circuits are on a PCB.

[@xaviero1412]

Scullcom Hobby Electronics​ nice, i have to make one. Thanks again sir

[@samhsavdr9647]

master job's

[@scullcomhobbyelectronics1702]

Thanks.

[@niemoge]

Excuse my stupid question, but do I get simmilar results when I take power supply, limit the current to 100mA and measure the voltage accross the resistor (4 wires) ? Just asking, whether its worth the effort to build this project. I would need it to measure resistances between 2 and 100 milliOhm. Thank you.

[@Mrhvac]

I think it's a great question. Yes. It's basically the same thing. This project includes building a good single-purpose power supply and an accurate single-purpose voltmeter. What makes the voltmeter unique is it's resolution. So, if you already have a capable power supply and a high-quality voltmeter with comparable resolution, then you would not need to build this.

[@niemoge]

@@Mrhvac Thanks a lot. The voltmeter I have may not be so precise. And to have this device portable, I will go for the project :).

[@fu1r4]

What is the range this milliohm meter can measure?

[@aklankrisz]

I think this circuit can currently measure 8-9 Ohms without any modification, but the display in use goes to "HHHHH" above 2Volts (2Ohms). Also see my newest post here.

[@aldob5681]

whats the point of using .1% resistor with a trimmer in parallel? 5% will do just fine

[@TheRcEngineer]

Low temperature coefficent

[@davidgorringe]

can I use farnell No. 2519475 please

[@scullcomhobbyelectronics1702]

The Farnell part No. 2519475 is OK. For some reason Farnell changed their part number.

[@tubeDude48]

I see a sticker, but NO t-shirt as of: 06/09/2022

[@GeorgeGraves]

Looks like OSH Park makes you order 3 boards. Anyone order 3 and have one to spare? I'd be glad to pay for it and shipping. Thanks! (I'm in the US)

[@jameshauser1507]

I am ordering some boards--are you still in need??

[@aqib2000]

Yes I am +James

[@jameshauser1507]

You can also reach me at [e-mail]

[@aqib2000]

James Hauser Only interested in millio ohm posted to uk

[@abeleski]

I am in need for one too. I am in Australia. If anyone has spares let me know. Cheers

[@mevlutcagdas8810]

grand master 12v mppt battery charger pls

[@DavidLeeMenefee]

The diet your on is obviously working for you. Stick with it...PEACE

[@scullcomhobbyelectronics1702]

Thanks you made my day. But it may be just the tight T-Shirt LOL :)

[@DavidLeeMenefee]

Glad my statement didn't offend. I don't think it was the shirt but what do I know. PEACE

[@scullcomhobbyelectronics1702]

Thanks, it just brought a smile to my face. Could be I have been doing a lot of manual work on the house lately and may have lost a little, you never know. Cheers, Louis

[@TheRcEngineer]

Hi I miss your highly educational videos. Hope you are healthy and got through the pandemic well. vy73 de OE1MIS

[@mevlutcagdas8810]

grand master 12v mppt battery charger pls