How to measure low ohms resistor with a multimeter / 1R0 R01 0.1 Ohm Shunt DMM and a dummy load test

hi guys did you ever try to make a less than one ohm resistor measurement with a digital multimeter probably you will get frustrated because no one of them will be good enough let's learn about it for many of our multimeters one ohm resistor will be in the limit of the specifications or the tolerance to read with your multimeter things get serious when we try to make a measurement with less than one ohm one of the main reasons why it happened is because many multimeters have a very high resistance in the test leads and that test lead resistance is very high compared with 0.1 ohm now if we try to go from 0.10 to 0.01 ohm forget it no one of our digital multimeters could be good enough for that so we have to go for plan b one plan b could be to get a specialized digital multimeter like a bench multimeter this kind of multimeters use four wires test for resistors and is what we call the kelvin test is an extra accessory in some of the multimeters you can get it and you can make circuits with it too and apply the system back to the multimeter what we get is something like this it's four wire sense we use two lines to give the voltage and the other two lines to make a measurement of the voltage the voltage drop in the resistor so the true we are not making a resistor measurement we are making a voltage drop measurement on the resistor as a plan c we can get a dummy lot an electronic load in this case what we do is we generate constant current with it and we apply it to the resistor we want to test using the voltmeter to get a reading of the voltage drop across of the resistor let's learn how to do it the circuit is very simple what i'm going to do i'm going to set up the dummy lot for one ampere with one ohm resistor one ampere will be one voltage drop across of the resistor in this case i will use the multimeter in voltage or millivolts if it is possible then i will get the reading across of the resistor guys very important don't even forget when you work with this kind of test with your work applying one ampere to one resistor you must remember you have power and that power you have to calculate the power i'm using one ampere in one ohm that will give me one bolt drop but also it will be one watt dissipation remember guys one watt is heat two watts is more heat three watts a lot of heat that's the reason why when we forget about calculating the watts we get a beautiful black spot in our workbench that will be there forever telling us you forgot to calculate the watts so do not start a fire at home here i'm applying 1.7 volts and i set the electronic load to one ampere let's see what happened when i turn it on now it's on and he tells me there is 986 milliamperes across of the resistor this is the resistor and the voltage across of the resistor with the test leads shows 978 millivolts that means my resistor that is one ohm with a tolerance of plus minus five percent is with one ampere across showing by ohm's law is 0.978 ohms with same settings 1 ampere 1.77 volts i switch the resistor for one resistor of 0.1 ohms let's see what happen when i turn it on now it's on this is my resistor with this tolerance plus minus five percent and i'm making a measurement of the voltage across others the resistor with one ampere and the multimeter says is 0.1 volt that guys is the proper way to get the message of a resistor less than one ohm with a digital multimeter thanks by watching see you next time

Channel: Bob. Kalpon

Views: 4,152

Rating: 4.9191918 out of 5

Keywords: bob kalpon, electronics engineering, how to fix, electronics, electronics workshop, eevblog, siglent, uni-t, fluke, tektronix, pcb, pcbgogo, samsung, huawei, sony, dell, hp, oscilloscope, osciloscopio, keysight, electronica español, epson, owon, ow18e, kaiweets, miliohms, how to test resistor, how to test a resistor, resistor testing, resistor measurement, how to measure a 0.1 ohm resistor, shunt resistor, shunt resistors

Id: LoENJCoiS1A

Length: 6min 49sec (409 seconds)

Published: Fri Jan 01 2021