Thanks for doing that Itsu. Also I am glad that DC amp Graham made for me is being used. That amp gets you into the region where small temperature difference between the Fe-Croc-clip thermocouples produce a reading. If you do your zeroing (that takes away drift in the amp) without the magnet present then touch one of the connections your body heat transfer will create a reading. Perhaps that explains why your readings take time to settle down. If you could arrange for the connections to be made without using your fingers that might prove this. My pleasure Smudge. Any idea what the Din interface on the side of the box (see picture 1) is for? When without any magnets close, in a stable situation and zeroing out, then touching the red wire connection side of the iron wire with my fingers, will show -10uV within 10s. It takes 20 min. or so for the measured value returns to 0uV (heat dissipated again?. Doing the same now with the black side connection of the iron wire, will show +10uV within 10s and taking another 20 min to return to 0. If you put another magnet at the other end of the Fe wire with its opposite pole close, then both ends will be negative with the centre of the wire positive. Perhaps you could try that. Be aware that the values mentioned e.g. 4uV will NOT be the same all the time, meaning a next SAME measurement will show perhaps 2uV and another 6uV, but the trend is the same (positive). I have split my stack of 10 magnets into 2 stacks of 5 magnets, each measuring 525mT. Putting 1 stack with its N-pole at the red lead end of the iron wire it will measure -4uV after 1 min., when then attaching the other stack N-pole to the black lead end of the iron wire (1.6m long and 1.5mm diam. by the way) then the measured value will increase and reach 0uV after 10 min or so. Now measuring with the black lead in the middle of the iron wire shows same value (0uV) Swapping the black side stack from N-pole to S-pole will show 4uV both with the black wire at the end or in the middle of the iron wire. So, putting the black wire in the middle of the iron wire seems to have no influence on the measurement.
« Last Edit: 2026-01-27, 13:47:59 by Itsu »
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