Mini fridge build part 2Posted: May 12, 2011
Because no project is complete without some sort of optoelectronic display, I’ve decided to attach an LCD to the fridge for the nerd-cred.
It appears the the mini-fridge is constructed with two shells, with the internal space filled with expanded polystyrene. The mini-fridge’s door is of similar construction, providing us with ample space in which to mount the LCD display. The LCD display itself is an inexpensive STN display with a paralel data interface consisting of 8-bit wide bus plus 3 control wires, courtesy of the HD44780 chip.
Accessing the inside of the fridge door is possible by finding the super-secret hidden screws behind the black foam seal (I can’t work out exactly why they need a whole 10 screws to keep on the front of the door).
Like candy, the fridge door combines a hard sugar-coated shell with a cruncy interior.
With the door panel off, I can mark out and cut the viewport. With that done, I next start cutting conduits for the cable. Because of the fridge’s two shell construction, there should be room for us to run a cable between the layers. I start by cutting a hole in the back end where the electronics are, and a corresponding hole at the top side.
Because the intervening space is filled quite tightly with styrofoam, it’s not a simple case of pushing the ribbon cable through, I need to pull it through with something. The only thing I had on hand at the time was my trusty metal ruler, which has a hole on one end. So I decided to shove this metal ruler up the inside of the fridge, and then try to attach some nylon cord to the hole and pull that through. The nylon cord can then be used to pull the ribbon cable through (there was no way of easily attaching the ribbon cable directly to the ruler.)
At this point, I feel that my time watching all those TV medical dramas have paid off – I have fashioned a paperclip into some hook, threaded a loop of nylon, and via an incision in the top of the fridge, I hooked the paperclip onto the hole of the metal ruler, laparoscopy style.
With the loop of nylon pulled through, I then used that to pull the ribbon cable through, which is actually a loop of flat CAT6 ethernet cable.
The cable is stripped, and soldered to a socket, plugged into the LCD, and duct-taped into position. I’ve made a bit of a dog’s ear of the polystyrene. No doubt I could have carefully cut the polystyrene to shape instead of ripping it apart with my bare hands. raaaar.
Finally, the cable is thread through another hold, and there is enough play in the cable to avoid stretching it as the door opens and shuts.