I will reiterate for the sake of those that may have missed earlier posts, but best to go back to page one for full details: You don't need to put the pickup in between the turns. Most of the scope shots I posted had the mag probe at a right angle to the end of the coil or parallel to the end of the coil, and up to 1.5 inches away. It greatly diminishes as you approach the center of the coil. This also showed up readily with an old long relay coil with a soft iron slug through the center as a pickup device. I also placed the heater into a large 6" hoop with about 50 turns of fine wire, with no magnetic core the pulse is easily visible. I'm sure the Magnetek probe I am using is just a small slug of iron or ferrite with maybe 1000 turns of fine wire and perhaps a loading resistor. It is weakly attracted to a magnet. The probe shows orientation arrows along it's length. It reads 1.52k ohms. Once the coil heats up the pulse disappears. It may be difficult to see it again until it is back down in temperature. I get the pulse up until the point where the coil glows orange then it fades into the noise as the buzzing stops. FYI the pulse reads about 350mV with this probe about a half inch from the end of the heater coil. This is equivalent to around 3.5 Gauss (with this probe, 100mV / Gauss), not very much. e.g. A large, linear wall wart produces about the same level at that distance. Peterae said: EDIT just an after thought, do you see the effect with the heater orientation to earth changed
How about a low volts relay coil with the core taken out, although this will only sit near the heater coil. not in between turns?
Orientation to earth does not matter. The relay coil will work with or without core. You seem to be getting plenty of low level noise from you hall sensor, but it looks random, nothing like the spikes I'm seeing. Strange. We need to calibrate our probes before we can make meaningful measurements. Can you bring the hall effect sensors near a known low level magnetic field to get a rough idea if your pickup is linear and good at low levels?
« Last Edit: 2012-08-15, 02:47:38 by ION »
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