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Experience with those cheap micro ohm meters

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Grossel

Well-Known Member
Hi.

I'm considering buying a cheap four pin micro ohm meter (**broken link removed**), just because it's cheap.

However, I cannot find any reliable sources on the net that states anything about the quality of those. I do not care if it is barebone, as long as the readings are correct.

Any of you have any epxperience with those devices, and hopefully can say if buying one is a waste of time?


Thanks
 
I bought one of the one's listed as per the one photo. I could measure low ohm resistors by touch the center pin and the outside. It seemed impractible to me so I opened the case and rebuilt it in another box and the results were great as shown. The resistor is is measuring is a 2.7 ohm resitor.
Hi.

I'm considering buying a cheap four pin micro ohm meter (**broken link removed**), just because it's cheap.

However, I cannot find any reliable sources on the net that states anything about the quality of those. I do not care if it is barebone, as long as the readings are correct.

Any of you have any epxperience with those devices, and hopefully can say if buying one is a waste of time?


Thanks
I bought one of the one's listed as per the one photo. I could measure low ohm resistors by touch the center pin and the outside. It seemed hard to handle to me so I opened the case and rebuilt it in another box and the results were great as shown. The resistor is is measuring is a 2.7 ohm resistor. The digits are less than 1/2" high and the circuit works from 12VDC. The last photo is of a EBAY entry that I got the atomizer from.
 

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I plan to use this device in field, so then I got to have a box and also a set of leads. Therefore I probably would look for a practically box.

Since this is a cheap device, I have some concerns about deviation over time - is it possible to calibrate this thing?

Thanks
 
I plan to use this device in field, so then I got to have a box and also a set of leads. Therefore I probably would look for a practically box.

Since this is a cheap device, I have some concerns about deviation over time - is it possible to calibrate this thing?

Thanks
I think it would be best to use the circuits posted by chemelec, as his can be calabrated. Looking at his posted schematic's I think is is possible to use just one battery as the common of both circuits is the same and I have used digital DVM's that can use a common battery.
 
Thanks for your answer. Right now I think my megger (Fluke) with 1/100Ω resolution provides good enough measurements for my needs.

Maybee I just buy one just to give it a try. Anyway, as I'm now aware that it probably lacks the ability to being calibratet I'll find an conductor with fixed resistance, and put that on a safe place, so I can measure the same conductor when some time is passed and I can see if the measurement have changed since then.
 
DO NOT TRY to use it with ONE Battery!
My Low Ohm Tester is ACCURATE.
I Can also Supply One Totally Assemble and Calibrated. FOR A PRICE!
 
DO NOT TRY to use it with ONE Battery!
My Low Ohm Tester is ACCURATE.
I Can also Supply One Totally Assemble and Calibrated. FOR A PRICE!
chemelec, please tell me why you would not use one battery for on source of power for the current source and the ohms reading. Thanks
 
chemelec, please tell me why you would not use one battery for on source of power for the current source and the ohms reading. Thanks

Fairly obviously because they don't (and can't) share power rails - you pretty well always need a separate supply when using digital meter modules (and in fact I've recently bought some little modules which provide an isolated 12V supply from a 12V source for just such a reason).
 
Fairly obviously because they don't (and can't) share power rails - you pretty well always need a separate supply when using digital meter modules (and in fact I've recently bought some little modules which provide an isolated 12V supply from a 12V source for just such a reason).

YES that is Correct
 
I bought one of the one's listed as per the one photo. I could measure low ohm resistors by touch the center pin and the outside. It seemed impractible to me so I opened the case and rebuilt it in another box and the results were great as shown. The resistor is is measuring is a 2.7 ohm resitor.

I bought one of the one's listed as per the one photo. I could measure low ohm resistors by touch the center pin and the outside. It seemed hard to handle to me so I opened the case and rebuilt it in another box and the results were great as shown. The resistor is is measuring is a 2.7 ohm resistor. The digits are less than 1/2" high and the circuit works from 12VDC. The last photo is of a EBAY entry that I got the atomizer from.

Those Meters are not as accurate as they could be.
For Accuracy you need a Four Wire Tester, to Greatly Reduce Contact Resistance.
Two to supply the Current to the Resistor and Two for the Sensitive Test Meter.
 
chemelec
This could make your system run on a single battery: Lower R8 to increase output V based on load.
chg-pump.png
 

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Looks like More Trouble than its worth.

Besides, What is the Problem with two 9 volt batteries.
A DPDT Switch turns them both Off when not in use.

I Get Two of these for $1.25 at the Dollar Store and Considering the Low Current Draws, they last WELL OVER three years.
The LCD Meter Just Draws LOW Milliamp and the Current Source only draws Current when actually Testing a resistor.
I connect up the leads to the Resistor, Turn it on and take a reading, than turn it off. About 5 Seconds of On time for a test.
 
Hey ChemElec looks like someone is plagiarizing your design. https://electronics-diy.com/electronic_schematic.php?id=951
Unless that is your website?

Thanks for this Info.

At Least they kept it showing my Company Logo on the PCB and Schematic.
Some Sites Steal projects and Remove all this info, making it look like they created it.

But they should have also put a "Link to My Project"
I have now contacted them about this.
 
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