I cook several pieces of meat at the same time. So rather than have multiple digital thermometers or another ET-73, I decided to build my own. This is version one. eBay is your friend, but I've got some cash in the thermocouples. Using a programmable logic controller and a thermocouple input card I picked up from eBay I put together this "temp monitor" for lack of a better term. Four inputs, one labeled CAB for the cabinet and three "zones" for three different pieces of meat. The word "CAB" above the temp will flash if the temp falls below 200 or above 250. The Z1, Z2 and Z3 will flash once the target temp is hit. Only two thermocouples were connected when the pic was taken:
This is the backside - thermocouple connectors and power input. The box will accomodate 6 inputs, but the thermocouple card will only allow for 4:
Hitting F1 will set the target temp for Zone 1, F2 for 2, F3 for 3. Temps adjust up and down in 5 degree increments with the up and down arrow keys. F4 returns to the main screen:
Right arrow takes you to the timer screen. Left arrow takes you back to the main screen:
Under the hood:
The Programmable Logic Controller or PLC is a very feature rich device that allows for programming modules, inputs, outputs, etc. They are often used in manufacturing/factory environments to run whole machines. Future expansion may include a stack light, horn or something else to alert to over/under temps or target temps getting hit. The Micro 300 HMI is pretty basic, but a 21" touchscreen could be added. With an ethernet module, the possibilities are endless. Have the PLC send a text with status updates, when temps are hit, that sort of thing. A web page that shows all the info on one screen? Anything is possible.
Yeah, I've got too much time on my hands...