jocanon
Member
I want to be able to control the speed of a simple 4 wire PWM computer type fan based on the temperature of various components. I bought this item which will arrive eventually on a slow boat from China:
https://www.ebay.com/itm/221878598666?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
It appears this little gadget will do what I need, except I want to make one minor tweak, that is, instead of controlling the temperature based off of the change in only 1 location, I want to expand it so the fan will rev up if the temperature heats up in one of several (probably about 4) different locations. I have a soldering iron and some soldering skills and I know enough about circuits to know (or at least think I know) that this is pretty easy to do, I just do not know enough to actually know how to do it (i.e. what components I will need).
So in short, I would like to create a schematic and BOM for parts that in the end will allow me to put a varying amount (at least up to 4) separate thermistors in 4 separate locations that all link back to one central location where if any one of the separate thermistors heat gets above a certain level then it will cause the speed to increase on the PWM speed controller (instead of just the one thermistor that comes standard with the eBay device I purchased).
Is this as easy as just connecting the desired quantity of thermistors in parallel and then plugging them all into the speed controller? Would this mean that the thermistor with the least resistance would set the speed (in other words the one connected to the hottest device at the time would be the one that would set the speed)?
edit:
now that I think about it, the conductivity of the thermistors would probably be additive. For instance, if I had 2 thermistors and both were open half way while being connected in parallel to the speed controller, then the fan would go at full speed, versus if I just had one that was open half way and the fan would go half speed. Am I thinking of this correctly? If so, is there a way to make a circcuit where they would not be additive, but just the hottest thermistor would set the speed and override all the others as if only the hottest one was the one connected at any given time?
https://www.ebay.com/itm/221878598666?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
It appears this little gadget will do what I need, except I want to make one minor tweak, that is, instead of controlling the temperature based off of the change in only 1 location, I want to expand it so the fan will rev up if the temperature heats up in one of several (probably about 4) different locations. I have a soldering iron and some soldering skills and I know enough about circuits to know (or at least think I know) that this is pretty easy to do, I just do not know enough to actually know how to do it (i.e. what components I will need).
So in short, I would like to create a schematic and BOM for parts that in the end will allow me to put a varying amount (at least up to 4) separate thermistors in 4 separate locations that all link back to one central location where if any one of the separate thermistors heat gets above a certain level then it will cause the speed to increase on the PWM speed controller (instead of just the one thermistor that comes standard with the eBay device I purchased).
Is this as easy as just connecting the desired quantity of thermistors in parallel and then plugging them all into the speed controller? Would this mean that the thermistor with the least resistance would set the speed (in other words the one connected to the hottest device at the time would be the one that would set the speed)?
edit:
now that I think about it, the conductivity of the thermistors would probably be additive. For instance, if I had 2 thermistors and both were open half way while being connected in parallel to the speed controller, then the fan would go at full speed, versus if I just had one that was open half way and the fan would go half speed. Am I thinking of this correctly? If so, is there a way to make a circcuit where they would not be additive, but just the hottest thermistor would set the speed and override all the others as if only the hottest one was the one connected at any given time?
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