Peltier Heat Off Cool ADC

228

02:47:21

Driving a Peltier element (here represented as motor to see direction change) for a wine refrigerator, allowing heating as well as cooling with an off state for the target temperature of 16-18°C.  The OpAmps are LM393 types.  The LEDs are here only for didactic and testing (easier than looking at relay contacts). There seems to be enough hysteresis in the working simulation to avoid continuous switching, would like to stay within 1°C = 1k range for the NTC.
If anyone comes with a better (read "easier") idea as well as the NTC setup at the front (actually NTC 10k with 13-15k range for 16-18°C range)
The top potmeter sets the target temp

published 6 years ago

kiani

6 years ago

The motor doesn't seem to change direction,, or have i missed a point.

solivi

6 years ago

Resistor network adapted so that the 14k = NTC value for 17°C + and - 1°C reacts correctly. Chnge value of 14k resistor (=NTC) = Orange line which must stay between Blue and Red lines

eekee

6 years ago

Neat! That's not actual hysteresis, but I'm sure thermal inertia will keep the relays from switching too often.

hurz

6 years ago

@eekee, even its not with hysteresis this little window will do the job and avoids oscilation the Tau is big enough 😜 or in other words, by reach on of the window bondaries it switches off and hopfully it does not shoot through to the window other side, then the bad will happen and it does oscillate 😜

add comment in editor

EveryCircuit is an easy to use, highly interactive circuit simulator and schematic capture tool. Real-time circuit simulation, interactivity, and dynamic visualization make it a must have application for professionals and academia. EveryCircuit user community has collaboratively created the largest searchable library of circuit designs. EveryCircuit app runs online in popular browsers and on mobile phones and tablets, enabling you to capture design ideas and learn electronics on the go.