ITTSB.EU Blog Forum
Electrical Metrology | Measurement Tips & Products | Calibration standards => Electrical Metrology for enthusiast => Topic started by: Kiriakos GR on June 22, 2017, 08:27:21 PM
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HIOKI RM3542A Resistance Meter this is a tool that I am aware that with out it I would be blind in the world of resistors. ;)
Recently I made a power supply for a friend with eight power transistors connected in parallel.
Therefore I was forced to buy several 5W 0.1R ( we called them as cement type) in Greece.
By having around HIOKI RM3542A this become a great opportunity to actually measure and make a conclusion of specific resistors tolerance by %, as this is usually not labeled any more.
In past two decades most such resistors were labeled as 5% or 10%.
Twenty years later that manufacturing technology supposedly become more precise, now they do not label in full such resistors.
Now lets see what I got speaking of measurements of twelve resistors.
HIOKI RM3542A set at measuring range of 100 milliohm , and comparator system set at 1% (+/_)
Resistor value ...... comparator Value
99.1073 .... - 0.983
99.0805 .... - 0.919
100.2165 .... + 0.226
99.5548 .... - 0.455
97.9256 .... - 2.074
100.0870 .... + 0.087
99.2508 .... - 0.749
97.6602 .... - 2.340
100.0140 .... + 0.014
98.1107 .... - 1.889
99.9268 .... - 0.073
99.7705 .... - 0.229
I do not know how to react speaking of conclusion.
Should I be happy ? That this factory aiming for 0.5% tolerance on average.
Should I get mad ? Because production quality this is far from be stable.
Another mystery with specific resistors this is their wattage, version of 22 Ohm resistors from this factory was unable to tolerate equal wattage with resistors made at 90s, and new resistors got up to 100 Celsius right away, and due wattage limitation they caused huge output voltage sag over load condition.
New resistors was indeed selected to match actual transistor specifications, and they do not get hot at all.
My thoughts now are that precision in resistance manufacturing this also influenced wattage, and this also become more precise, this now translates that hobbyist makers are in higher risk of watching resistors to get in flames, when they will do wrong parts selection.
Professional electronics engineers they have modern tools, and parts selection will be precise.
And in case that an electronic part this fails, then it is a manufacturer fault.
Conclusion
Within 2017 precision this is all around us.
And your measuring gear this must be equally precise according to electronic spare parts that you are going to work with.
Low Ohm measurements this is a job for measuring equipment which they have lower measuring range, this be close to measuring value.