Half Ohm milliohm adapter is ready! Multimeter adapter that transforms any multimeter into a precision milliohm meter and debugging device. Notice that your multimeter is useless when measuring small resistances, like connectors or tracks. So did I, so I built this: 1% precise, small and cheap adapter for you. Ultra useful for finding position of shorts on your board. I have already used it tens of times. Get one!
Usage:
- Connect the adapter to your multimeter and power both of them.
- Half Ohm should light up brightly.
- Switch multimeter to voltage range.
- When nothing is connected, you can read the battery voltage. Battery is 3V CR2032, so if the voltage is lower than 2.6V, consider changing the battery.
- When connected with a resistance smaller than 1Ω the voltage in mV shows measurement in mΩ. So 1mV = 1mΩ, 10mV = 10mΩ and so on.
- Connect your probes to adapter and connect them both with each other (press into one pad or something like that) the readout is more or less the resistance of your probes, connections and meter itself. Zero that with RELATIVE button or just memorise it.
- Measure the real thing, the difference between last and this measurement is your resistance.
Finding position of short circuits:
Connect and power everything. Press your probes to shorted tracks. Probe around. The direction where the resistance decreases is the direction of the short.
Calibration:
If you want to test or calibrate the adapter then you can use 100mΩ resistor that is included. On the bottom edge of the PCB there is big 1206 100mΩ 1% resistor that you can measure.
The sources:
Schematic and board in KiCad. My KiCad libraries! Schematic in PDF.
Probably just my noob status with Kicad...but the HalfOhm project doesn't find the opa335, the coin cell conn, etc. and I don't seem to find them your Kicad libs either.
That was my bad. I had accidentally deleted some of the library components. Now I redrew the components.
Any chance you can post the schematic in PDF form? I don't use KiCad.
Posted.
What is the usable range?
Thanks,
Brad
1mΩ to 1Ω. Under 10mΩ the pressure on the probes starts playing almost too much. This will probably improve with sharper and/or golden probes.
Hi Jannus,
Where is the resistor for calibration connected to?
All the resistors used in the schematic are precision resistors?
Thank you very much.
Bimi.
Calibration resistor is not connected to anything. You must use your multimeter leads to measure it.
And all the resistors are 0.1% precision resistors.
What part are you using for the banana plugs? I'm working on a project that I'd like to plug directly into a power supply with banana jacks, but can't find any form of SMT banana plug part.
I'm using hobby RC 4mm banana connectors. They are not SMD, I made the shape of the PCB weird so it would hold the connectors in place.
Hi, I just received my Half-Ohm. It works nicely.
Q: Why is the shunt-current so high?
The lower the shunt current the better the op-amp has to be. At the moment the balance between currents and precision is the best I could do.
It is possible to make the current 2x smaller and lose 2x of precision.
Mõni "Half Ohm - milliohm adapter" veel postiga saata on ? https://youtu.be/wJr7Ts86wpk?t=686
Your guide is very detail comprehensible thank so much.
Hello Jaanus,
Greetings from Lithuania! Great job! I would like to ask what zener diode (U1) you use? And is it possible to expand measure range up to 2 ohms?
Thanks for Your answer!
Best regards
I use precision voltage reference, not zener. Voltage reference is needed to get the claimed spec. It is possible to expand measurement range by changing resistors or using higher reference voltage. Both would have impact on absolute precision.
Schematics diagram of half ohm meter please
precision voltage reference part details, please
Thank you so much for wonderful product , it's work perfectly as per all your updates
Great job !
HI, I saw yor project on EEVBlog,
dave pointed out, that the LED is power hungry.
In My experience, the best results you can get with Brightness/Power Saving with Blue LED working at 0.6-1mA
I just like the helpful information you provide in your articles
Very well presented. Every quote was awesome and thanks for sharing the content. Keep sharing and keep motivating others.
I am truly thankful to the owner of this web site who has shared this fantastic piece of writing at at this place.
I really like reading through a post that can make men and women think. Also, thank you for allowing me to comment!
For the reason that the admin of this site is working, no uncertainty very quickly it will be renowned, due to its quality contents.
I do not even understand how I ended up here, but I assumed this publish used to be great
Awesome! Its genuinely remarkable post, I have got much clear idea regarding from this post
very informative articles or reviews at this time.
Nice post. I learn something totally new and challenging on websites
it'd be such a criminal offense to not share this article with everybody who lives in writer California, it's really informative enough.
Great information shared.. really enjoyed reading this post thank you author for sharing this post .. appreciated
Hi there to all, for the reason that I am genuinely keen of reading this website’s post to be updated on a regular basis. It carries pleasant stuff.
Hi there to all, for the reason that I am genuinely keen of reading this website’s post to be updated on a regular basis. It carries pleasant stuff.
Hi there to all, for the reason that I am genuinely keen of reading this website’s post to be updated on a regular basis. It carries pleasant stufff hahaha
Konular mükemmel olduğu gibi site teması da içeriğe müthiş uyum sağlamış. Tebrikler
I very delighted to find this internet site on bing, just what I was searching for as well saved to fav
This was beautiful Admin. Thank you for your reflections.
Hi there to all, for the reason that I am genuinely keen of reading this website’s post to be updated on a regular basis. It carries pleasant stuff.
Nice post. I learn something totally new and challenging on websites
Nice post. I learn something totally new and challenging on websites
What I gathered from what you shared here, it's higher to grasp US and not need us then to wish us and not know us, is that this what you're making an attempt to say?
Lorem ipsum dolor sit amet, consectetur adipiscing elit.
fcuk you google fcuk you googlefcuk you googlefcuk you google
You are an inspiration, gorgeous.
Dziękuję , i liked your site.
I’m often to blogging and i really appreciate your content. The article has actually peaks my interest. I’m going to bookmark your web site and maintain checking for brand spanking new information - locask.com.
very informative articles or reviews at this time.
Nice post. I learn something totally new and challenging on websites
I appreciate you sharing this blog post. Thanks Again. Cool.
I am truly thankful to the owner of this web site who has shared this fantastic piece of writing at at this place.
I just like the helpful information you provide in your articles
very informative articles or reviews at this time.
I do not even understand how I ended up here, but I assumed this publish used to be great
Decker's Deck is a deck builder and designer in Mississauga, Toronto, Vaughan and all communities in Ontario. We offer personalized Composite Decking options at affordable prices. For deck railing options, you'll want to choose Decker's Deck for high quality Cedar Decking services.
very informative articles or reviews at this time.
For the reason that the admin of this site is working, no uncertainty very quickly it will be renowned, due to its quality contents.
I just like the helpful information you provide in your articles
Hi, thank you so much for this great project! I would like to build it. However, I am a little confused about the banana jacks/plugs. On the schematic it looks like P2 and P4 are connected to Ground. Is that correct?
Canlı maç izle hizmeti için sitemizi tercih edebilirsiniz
We are building our site for you, where you will find the apk download option the most accurate.
casino sitesi özelliklerimize sizlerde bi arada keyifle bakabileceksiniz.
Ankara kanal vidanjör, kanal açma hizmetleri için bizimle iletişime geçin.
As I read this essay, I found it to be really interesting. The author's work amazed me since he expertly selected the most appropriate terms to utilize in his essay. The terms he utilized make this post stand out and be interesting. As I read the piece, I had the feeling that I could fully understand its substance and that the author had written it just for me or my school of thought.
Thanks for the beautiful post.
I very delighted to find this internet site on bing, just what I was searching for as well saved to fav
This was beautiful Admin. Thank you for your reflections.
I very delighted to find this internet site on bing, just what I was searching for as well saved to fav
Savoybetting bonus sayfasında bulunan bonuslardan faydaylanabilirsiniz.
I just wanted to take a moment to express my gratitude for the great content you consistently produce. It's informative, interesting, and always keeps me coming back for more!
Let us know in the comments which of their posts has resonated with you the most.
I like the efforts you have put in this, regards for all the great content.
Your article is a great reminder of why we need to keep fighting for change. Thank you for being a voice for those who can't speak up.
very informative articles or reviews at this time.
I like the efforts you have put in this, regards for all the great content.
Unlock the potential of your online identity with Flickerlink.
Thank you for considering different viewpoints and providing a fresh perspective in this article.
Every couple has a different style. Some want specific color schemes or a theme, others are looking more for a specific feel or vibe.
Your article is an excellent resource for anyone interested in this topic. I appreciate the way you presented the information in a clear and concise manner.
Your writing is so engaging and easy to read. It's clear you have a talent for communicating complex ideas in a simple and approachable way.
Your article is an excellent starting point for anyone interested in learning more about the topic.
The best hosting in our univers, visit to:
I appreciate the thoroughness of your article. You covered all aspects of the topic in a comprehensive and engaging way.