help with temp unit for my Unimog

I forgot to mention that the Unimog has a 24 volt charging system but I could get or make (any help or plans for these) a 24V->12V converter. If it matters, I have a couple OLD laptops around that I suppose could be used as a display if someone told me how.

thanks again doug

Now would be a good time to learn AVR programming. That is a Microprocessor Chip with everything in it.. using an ATmega chip, there is one series that employs 11 ADC inputs (analog to digital), with those, you could use RTD type thermocouples directly on the input. The chip as a lot of io's and easy to work with. You do need to get the Dev kit for it. the Kit comes with one of those chips to play with. The output's can be PWM (pulsed width modulated) to give you analog or simply employ some Serial display device for a report. P.S. they do make multichannel Temp monitors and controllers.

Hi, Doug. Cheap, easy and also able to be done by a newbie? Possibly this is a bridge too far.

The basic problem is that a thermocouple produces a very small voltage (millivolt level), which has to be preserved faithfully through the switches if you want to retain the measurement accuracy. The precision isothermal switch you're looking for is generally not too happy with the extremes of temp, humidity and vibration of the automotive environment. Store-bought electronics solutions are pretty expensive, and the do-it-yourself methods can be relatively inexpensive, but require that you know quite a bit about what you're doing (and also require cold junction compensation for accuracy).

If I were in your shoes, I'd just run the multiple thermocouples to a small box in the cabin. I'd attach them to yellow female bulkhead connectors (if it's K-type) for each one. When I wanted to make measurements, I would just pull out my K-type jumper (with miniature male connectors on each end) wire and plug in one at a time to the DVM with temperature reading.

I hope this has been of help.

Good luck Chris

It seems that the thermocouple idea might have some problems that I didn't know about. Cold junction this and that. Would a temp sensor from a car that varies resistance according to heat be more doable? there are several small 1/8" pipe thread, 1 wire, grounded body sensors that I could use and make fit instead. thanks again.

doug