3 ms·
It could be much simpler. If I understood the problem, a differential amplifier (any opamp would do) wired to the temp sensors would output a voltage proportion
by squarefoot 6y ago
It could be much simpler.
If I understood the problem, a differential amplifier (any opamp would do) wired to the temp sensors would output a voltage proportional to the difference between the two temperatures, plus adjustment. This voltage then can be used to drive a pwm generator wired to a h-bridge that drives a reversible fan that would pump air with speed and direction depending on the difference between two temperatures, so that it could be used both ways too warm up or cool down.
The same could also be done the digital way by using for example an uber cheapo ATTiny85 small board wired to the sensors, plus the fan and its driver, then doing all in software. That little critter has just the right amount of ports for the job and then some.
Not checked on paper (especially the first) but on principle both should work and also would be extremely cheap.
- phyzome 6y agoI have to ask -- are you aware of the existence of bimetallic strips, and how they can perform this function in a completely mechanical way? (No electricity.) It doesn't get you active air movement, of course, but it has worked for years in greenhouses.
- Scoundreller 6y agoMy only worry with that is having one end hang out the window. The household round thermostats are still like $35+ each.
- squarefoot 6y agoI know about them; that would be the simplest and safest possible solution indeed, however they are on-off switches and also have a fixed (sometimes excessive) hysteresis which couldn't be ideal for some uses.