Replace wine fridge circuit board with Arduino?

Hi,
I'm a fairly new hardware tinkerer, have not used Arduino, and have only a basic understanding of electricity. I am also a Software Engineer (which, I hope, counts for something as I explain this project).

I acquired a 2-zone Thermoelectric (peltier) wine fridge that appears to have had the power circuitry burned out. It has 2 circuit boards (power daisy-chained). The first one in series does not appear to work at all, and the 2nd works, but gives an intermittent humming/buzzing sound when the peltier cooling fan turns on (which, I think may be bad capacitors). The components connected to the 'working' board appear to work properly (peltier, fan, interior LED lights, and digital readout and buttons on the front panel).

With this in mind, I was thinking it may be somewhat 'straight-forward' to replace the circuit boards in the fridge with one (or 2) Arduino boards, connecting it to the existing other components (fans, peltiers, thermometers, etc).

Being such a newbie at this, i'm not sure yet which components I need, but I've attempted to make a list below, just in case I'm on the right track.

I think I will need:

  • An alternative power source (12v for fans/peltiers, 5v for Arduino(s))
  • A SSR / Mosfet / H-bridge for providing enough power to the peltiers/fans (these are just guesses)
  • Software libraries to interface with each of the components
  • Code to control the peltiers, fans, thermometers, LCD display, and set temperature buttons

I don't know if I'm on the right track here or not, but if someone would be kind enough to give their two cents on this project idea I have, I would be very grateful!

Seems like you'd need some temperature sensors somewhere in all of this.

I’m fairly sure the temperature sensors are already part of the fridge’s components. I haven’t followed every wire to track down where they are in the fridge compartment, but there’s got to be temp sensors already installed, right?

rlsix:
I'm fairly sure the temperature sensors are already part of the fridge's components. I haven't followed every wire to track down where they are in the fridge compartment, but there's got to be temp sensors already installed, right?

Sure. Do you know what they are and how they work? That's going to be the real problem here.

Take the LCD for example. Coding for an LCD is easy IF you know what LCD you have and how to control it. For some random LCD in some random piece of equipment where you don't know what type of driver it has... You might as well give that up. Hacking it would take so much more time and money than just buying a new wine fridge.

So unless you can identify these parts and track down their documentation they're worse than useless to you.

Do you have complete schematics of the internals of that fridge?

Otherwise it's probably cheaper to just buy a new one...

Hi rlsix,

(first of all if you like hardware tinkering it is always worth to get an arduino because they are great fun anyways, but besides that)

Like Delta_G said it can be very hard to interface with all the components if you don't know what they are. However, you could just replace all of the broken section with an arduino based system. Peltiers and fans and temperature sensors are relatively cheap (unless you want high performance, but it's a wine cooler so i assume not). There are also pretty standard options for interfacing an arduino with an lcd and some buttons for temp control.

From a software point of view this would mean:

read temp sensor
use something like PID to calculate a control response (so if the temperature rises the cooler starts cooling more)
send this to the peltier and fan
display temp on lcd
read buttons for different temperature setpoint.

You could probably use the old power source depending on what voltages it provides (multimeter time)
The code should be simple (especially since there are so many cool arduino projects which have shared their codes just look for arduino peltier fridge).
An H-bridge could indeed be used to control the voltage for the peltier (there is no real danger in having the fans run on full constantly but if you want you could also control them with an H-bridge).
Most libraries are easy to find (especialy if you use things commonly used with arduino's)

Hopefully that helps you along a little bit.

Regards,
Teunman

teunman:
An H-bridge could indeed be used to control the voltage for the peltier (there is no real danger in having the fans run on full constantly but if you want you could also control them with an H-bridge).

It's not a good idea to use an H-bridge for those.

You don't use half the bridge (both heaters and fans don't have a reverse), and the high side of the half you do use is just causing unnecessary losses. A single MOSFET makes much more sense.

A similar "wine cooler" problem was recently reported here.

jremington:
A similar "wine cooler" problem was recently reported here.

Thanks for the link, I'll go take a look and see if that helps me out.