dBel beat me to the punch! I also just took a chance on one of the 903 series. This one being the AMR. With my LCR meter I’m getting 0.5 DCR and 53.5mH. Also took a reading with the old parts tester. DCR also 0.5 but maybe not the best at measuring inductance.
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Hi Daanve, is there a webshop for these c-cores? Google did not come up with anything usefull.
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=&ved=2ahUKEwjFkPSdlZnxAhUPHewKHbFrAaIQFjACegQIBBAE&url=https%3A%2F%2Fwww.semic.cz%2F!KATEGORIE%2F6K%2FCatalogue%2520Silicon%2520steel%2520cores.pdf&usg=AOvVaw2beLQIUuSzGLeh9_BzvOug
https://www.google.com/url?sa=t&rct..._06_2018.pdf&usg=AOvVaw1M9_t8r0k2n5WltkA0YO4G
https://www.google.com/url?sa=t&rct..._06_2018.pdf&usg=AOvVaw1M9_t8r0k2n5WltkA0YO4G
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Inductor DCR Measurement
How do you check the resistance of an inductor? You can't just use your multimeter on ohms setting.
Suppose you need to measure a device like an inductor with DC resistance in the milliohm range. We had a production quality issue and needed to evaluate some inductors. The target resistance of the part was between 63 and 70 milliohms. Try to measure it with your Fluke 87V and you'll read something in the 0.5 ohm range. So how do you accurately measure it without an expensive micro-ohm measuring instrument? This is how we did it:
Make a "test fixture" from copper tape and a half business card. Add Kelvin sense leads. Solder the inductor on the fixture. Connect the Fluke 87V to the sense leads in voltage measurement mode and connect the power supply to the (copper tape) power leads with current limit set at 1 amp. The reading in millivolts drop on the sense leads is equal to milliohms of DC resistance in the part. Done.
How do you check the resistance of an inductor? You can't just use your multimeter on ohms setting.
Suppose you need to measure a device like an inductor with DC resistance in the milliohm range. We had a production quality issue and needed to evaluate some inductors. The target resistance of the part was between 63 and 70 milliohms. Try to measure it with your Fluke 87V and you'll read something in the 0.5 ohm range. So how do you accurately measure it without an expensive micro-ohm measuring instrument? This is how we did it:
Make a "test fixture" from copper tape and a half business card. Add Kelvin sense leads. Solder the inductor on the fixture. Connect the Fluke 87V to the sense leads in voltage measurement mode and connect the power supply to the (copper tape) power leads with current limit set at 1 amp. The reading in millivolts drop on the sense leads is equal to milliohms of DC resistance in the part. Done.
The actual way to measure an Inductor's DCR value is by using a Kelvin sensing path across the leads and applying current across the Inductor. As the DCR of Inductor is the DC resistance of the copper wire, it will produce a voltage across the Inductor's terminal based on the Ohms law, V = I x R.
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I generally use a signle IXYS and a CPU cooler and fan as the heat flux of 75w from a single part is probably more than a passive heatsink can spread out well spatially. Hence the choice to use several lower power rated, less expensive MOSFETs to permit spreading the thermal load over a wider area to keep the part well within it safe operating area. The three TO-247 MOSFETs spread over a 300mm deep heatsink in DIYA UMS format allows for more people to be able to build it as many are not comfortable or will even consider non-passive heatsinsks.
