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| Can a variable thermal shut off circuit be build? |
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| David Hess:
We have used the metal can AD590 as the temperature sensor for this sort of application in the past but they are pretty expensive. The current output is easier to use. I would build a latching circuit using the temperature sensor, a reference, and an operational amplifier as a precision comparator. With proper calibration, the trip point can be set with a potentiometer and multimeter. An external temperature trip might be a useful feature to build into a power supply. |
| FriedMule:
--- Quote from: David Hess on August 03, 2019, 03:18:32 am ---We have used the metal can AD590 as the temperature sensor for this sort of application in the past but they are pretty expensive. The current output is easier to use. I would build a latching circuit using the temperature sensor, a reference, and an operational amplifier as a precision comparator. With proper calibration, the trip point can be set with a potentiometer and multimeter. An external temperature trip might be a useful feature to build into a power supply. --- End quote --- The dmm idea sounds great, maybe even use one of the dmm displays from Ebay? Yes and maybe in an electronic load, I am wondering on why that is not standard in the top of the range PSU / Loads. May I put an enormous strange on your genres help? :-) Could you maybe try to draw a schematic that I can start my project from? |
| David Hess:
--- Quote from: FriedMule on August 03, 2019, 09:24:55 am ---The dmm idea sounds great, maybe even use one of the dmm displays from Ebay? --- End quote --- That could work but I always just connected a multimeter temporarily to set the trip point. --- Quote ---May I put an enormous strange on your genres help? :-) Could you maybe try to draw a schematic that I can start my project from? --- End quote --- There is not much to draw. Filter the signal and reference voltage before the comparator. Using an operational amplifier makes this easier because of lower input bias current. When I did it, I latched the output by using the operational amplifier to trigger an SCR which pulled the output to the load disconnect down to ground and kept it that way until reset. |
| FriedMule:
Thanks a lot, I'll try to se if I can draw something that do that:-) Would you mind looking at it when / if I can draw it? |
| David Hess:
--- Quote from: FriedMule on August 03, 2019, 11:11:38 am ---Thanks a lot, I'll try to se if I can draw something that do that:-) Would you mind looking at it when / if I can draw it? --- End quote --- Just post it. Everybody will comment on it. |
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