Timeline for Help with closed loop heat controller (for a non engineer)
Current License: CC BY-SA 3.0
10 events
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| Jul 10, 2015 at 19:39 | comment | added | Ryan | Also thanks for the PID recommendation. From what I've read a PID controller would greatly simplify my control circuit. Almost sounds like magic at this point. | |
| Jul 9, 2015 at 21:51 | comment | added | Ryan | Now that I think about it, RTDs would probably work just fine since they don't rely on heat input as a source of energy, and since you have mentioned your drilling idea, I no longer would need to rely on the flexible TCs in the link I sent you. | |
| Jul 9, 2015 at 21:46 | comment | added | Ryan | Ok, I also thought this would be the simplest, but I've been looking into it some more, and Thermocouples produce very weak voltage (10 mV for type K TCs in the <100'C range) and most slip rings I've looked at provide a noise rating of <10milliOhms, which, if I am thinking about this correctly, would be enough resistance to seriously reduce the current. Given these details, would you still go ahead with this method? Also in case you are interested I found some flat (albeit expensive) TCs: omega.com/pptst/SA1.html but drilling a hole in the disk sounds like a better solution. | |
| Jul 9, 2015 at 17:02 | history | edited | DLS3141 | CC BY-SA 3.0 |
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| Jul 9, 2015 at 16:51 | comment | added | DLS3141 | Unless you only want data every hour, I'd abandon the magnet idea. While you could use a magnetic strip or a series of magnets, there will be variation in the magnet's strength along the strip and variation between each magnet that you'd need to account for in calibration. Based on what you've said, and your I would start with a TC or RTD, a slip ring and a cheap PID controller from eBay for your control system. | |
| Jul 9, 2015 at 16:44 | comment | added | DLS3141 | I've never used slip rings at speeds that low, typical speeds of 400rpm up to 20k rpm., so, I honestly don't know. I would expect that the noise issues would be low, but that's not based on direct experience at those low speeds. I've used a dab of epoxy to attach thermocouples to metallic and ceramic surfaces. The epoxy provides good enough thermal contact for wjhat I was doing, much better than just placing the TC onto the surface. Another approach I've used is to drill a hole into the piece, just big enough for the end of the TC and inserting the TC. | |
| Jul 8, 2015 at 22:33 | history | edited | Air | CC BY-SA 3.0 |
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| Jul 8, 2015 at 21:56 | comment | added | Ryan | Also: my disk rotates very slowly, only about once per hour, so would noise with a slip ring still be an issue at this rate? | |
| Jul 8, 2015 at 21:44 | comment | added | Ryan | Ok thanks, this is an interesting suggestion. I've looked a bit into IR sensors, and a simple workaround for variable emissivity is to stick a piece of masking tape onto your surface and use that as a reference to calibrate the sensor to account for emissivity. I do also have a digital thermal couple to calibrate the IR with, but I've found that it doesn't make enough contact with our flat metal disk to be accurate, since it is basically just a blunt-ended wire that rests on the aluminum. Would a magnet suffer from deterioration over time? | |
| Jul 8, 2015 at 16:59 | history | answered | DLS3141 | CC BY-SA 3.0 |