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Electronic Circuit- Help Answered


My name is Daniela, I'm student and I need help to anyone who can help me :D

Project goal: Control the temperature inside a closed chamber

I need help to connect the all components and I don't know how because I'm new in this . I don't know how to amplify and to maintain the current, voltage so as to the whole circuit should work, what value is need for resistance, capacitors and other necessary components.

I use a launchpad MSP-EXP430FR4133. I prefer to use power supply 3.3V (not 5V). To amplify the voltage I use a DC Boost Converter 2A power supply module MT3608 where the module output voltage can be adjusted.

The temperature sensors it for hot side and cold side of Peltier element. A good size to have on the hot side is about 3 times as big a heatsink than on the cold side to don't find that both sides are getting hot.

I have attached below a Block diagram, a List of Components, Description and What it looks like the final project.

Please help me :D :)

Datasheet: MSP-EXP430FR4133 :http://www.ti.com/lit/ug/slau595b/slau595b.pdfs

FAN-BM5115-04W-B50-L00 : :http://www.farnell.com/datasheets/2266998.pdf?_ga=2.72941011.1375318338.1566287615-2140457824.1565329371

LM35DZ/NOPB :https://www.ti.com/lit/ds/symlink/lm35.pdf

LMT86LP :https://www.ti.com/lit/ds/symlink/lmt86.pdf

TMP112AIDRLT :https://www.ti.com/lit/ds/symlink/tmp112.pdf

TEC-40-33-127 :https://eu.mouser.com/datasheet/2/433/Wakefield_Vette_Thermoelectric_Cooler_Full_Data_Sh-1501217.pdf

MT3608 :https://www.olimex.com/Products/Breadboarding/BB-PWR-3608/resources/MT3608.pdf


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1 year ago

Probably a bit too late, but just wanna add, that for the tightest control, don't have any un-powered periods using PWM for a Peltier/TEC, if you can "afford" the higher power use.
This meaning that when not powered hot, it's powered cold (if that makes any sense).
This principle is used in robots, where positional precision is more important than power consumption and will hold any load (that can handle it) in a really firm grip.
Have a nice day :)


1 year ago

Sound like a cool (hahaha!) project!
Be aware, that you could potentially make the mechanics MUCH simpler with a bit of electronics:
A peltier can be reversed. So If you supply + to RED and - to BLACK it works as expected. But if you reverse the polarity, ( - ro RED, + to BLACK), it will also reverse the cold and hot side.

This is how i would tackle this project:
- Have a controllable fan (PWM)
- Have a controllable Powersupply (PWM)
- Have the option to reverse polarity on the Peltier (H-Bridge or Relais)

This would simplify it massively! No more servos and gates to be regulated. The fan acts as regulator (No fan, no hot or warm air is pushed into the chanber), you dump heat or cold to the outside of the box which has basically infinite heat- or Cold capacity unlike your closed box (less influence to the Peltier side you want, more aggressive temperature-changes and temperatures possible)

So basically:
- Room too warm, Peltier warmer than Room: Switch off fan, Lower PWM Peltier, wait till T peltier < T room, Switch fan on
- Room too warm, Peltier cooler than Room: Raise PWM Peltier
- Room too cool, Peltier cooler than Room: Switch off fan, Raise PWM Peltier, wait till T peltier < T room, Switch fan on
- Room too cool, Peltier warmer than Room: Lower PWM Peltier

- In all cases, if the lowering of PWM is not sufficient (Warmth/cold comes from outside of the box into the box and not the peltier is heating/cooling too much, the peltier can be reversed and
- Cool massively if too warm room
- Heat massively if too cold room

2019-08-21 11.15.34.png

Reply 1 year ago

It's a good idea. Can you help me to creat the schematic circuit?
I'm trying to understand how it works and I would like you to explain to me.
Initialy I need some help to connect the peltier element. I want to connect and control the element using MSP430 as launchpad(power supply: 3.3v) I use TEC-40-33-127. I attached below some specifications of the device.
I want something similar as in the schematic.


Reply 1 year ago

Read up what a H-Bridge is. (Wiki/H_bridge) It will give you the understanding of how to use the no longer 1 switch (IRF1405) but 4 of those in a H-Bridge-Configuration.
This way, you will be able to drive the peltier in both directions and therefore change the one side inside your room from heating to cooling and vice versa.
Think on how to connect and control the 4 switches (4x IRF1405) to power the peltier in both ways / how to use the H-Bridge in both polarities.
Read up on PWM (Pulse width modulation). Normally, the analogue-Outputs of a uC are PWM. Check if this is the case with the MSP430. I think it should.
With PWM, you are no longer bound to "FULL STEAM AHEAD" but can gently increase and decrease the power to the peltier.
4: Try to draw a flow of questions and decisions on how YOU would determine if you need to lower the power of the already hot peltier in a little bit too warm room or even maybe if you need to actively reverse the peltier and start cooling instead of heating less...
This will give you a starting point on how to regulate the room.

Edit: https://www.modularcircuits.com/blog/articles/h-b... is a quite good writeup on many of the topics discussed here.