| Electronics > Beginners |
| DIY milliohm shunts |
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| ledtester:
I'm interested in making an ~10 mOhm current sense shunt, but if I made it out of 20 AWG copper it would be about a foot long. The shunts you see in multimeters and digital panel meters are only an inch or two long. What kind of wire are they using??? |
| Kleinstein:
Low ohms shunts are often made form a alloy called Manganin. Due to the alloying elements it has a considerably higher resistance than pure copper. Pure copper does not work well for a 2 nd reason: the resistance changes quite a lot with temperature (some 3500 ppm/K), the special resistor alloys have a much more stable resistance (often < 100 ppm/K, good ones < 10 ppm/K). For a DIY replacement one could use stainless steel - it has a relatively low TC. However soldering is not easy and needs special flux. Brass is also considerably better than copper, but the TC is not as low as with stainless. |
| Brutte:
There is also constantan alloy. Definitely, copper is not suitable. There are 10m SMD resistors available, 100ppm are not that expensive. With 1W resistor you can get as high as 10A. |
| HighVoltage:
Look for Manganin resistors by Isabellenhütte (Germany) they are reasonable in price and very good and you can find good datasheets on them. |
| Bud:
"Resistance wire" on eBay or Amazon. |
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