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help with temp unit for my Unimog

D

doug

Jan 1, 1970
0
Hello everyone,
Thanks in advance for anyone who might offer some help. I have a
Unimog with a few heat sensitive areas that I would like to keep track
of. The biggest area of concern is the transmission followed by the 4
portal reduction boxes and the 2 drive axles. For the time being I'm
using my digital multimeter and what I believe to be a "K" type
thermocouple. The thermocouple thingy is zip-tied to the trans.
dipstick with the wires running into the cab. I'd like a cleaner,
more permanent solution the I could maybe monitor more systems at
once. I can get the thermocouples fairly cheaply and can probably
find a way to mount/install them easily enough. Does anyone have or
know of a way to build (I know very little electronics so go easy on
me) something to monitor several of these at once or even cycle
through them automatically or with the push of a button or turn of a
knob. A small lcd display would be nice, or some way to display it on
another screen/monitor as I'm trying to figure out a back-up camera
and could display the temp info on that monitor. It's a small 5.5
inch b&w crt display with a few inputs. I'm open to anything. cheap
and easy being impotant as I am both.

thanks,
doug
 
D

doug

Jan 1, 1970
0
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
 
J

Jamie

Jan 1, 1970
0
doug said:
Hello everyone,
Thanks in advance for anyone who might offer some help. I have a
Unimog with a few heat sensitive areas that I would like to keep track
of. The biggest area of concern is the transmission followed by the 4
portal reduction boxes and the 2 drive axles. For the time being I'm
using my digital multimeter and what I believe to be a "K" type
thermocouple. The thermocouple thingy is zip-tied to the trans.
dipstick with the wires running into the cab. I'd like a cleaner,
more permanent solution the I could maybe monitor more systems at
once. I can get the thermocouples fairly cheaply and can probably
find a way to mount/install them easily enough. Does anyone have or
know of a way to build (I know very little electronics so go easy on
me) something to monitor several of these at once or even cycle
through them automatically or with the push of a button or turn of a
knob. A small lcd display would be nice, or some way to display it on
another screen/monitor as I'm trying to figure out a back-up camera
and could display the temp info on that monitor. It's a small 5.5
inch b&w crt display with a few inputs. I'm open to anything. cheap
and easy being impotant as I am both.

thanks,
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.
 
C

Chris

Jan 1, 1970
0
doug said:
Hello everyone,
Thanks in advance for anyone who might offer some help. I have a
Unimog with a few heat sensitive areas that I would like to keep track
of. The biggest area of concern is the transmission followed by the 4
portal reduction boxes and the 2 drive axles. For the time being I'm
using my digital multimeter and what I believe to be a "K" type
thermocouple. The thermocouple thingy is zip-tied to the trans.
dipstick with the wires running into the cab. I'd like a cleaner,
more permanent solution the I could maybe monitor more systems at
once. I can get the thermocouples fairly cheaply and can probably
find a way to mount/install them easily enough. Does anyone have or
know of a way to build (I know very little electronics so go easy on
me) something to monitor several of these at once or even cycle
through them automatically or with the push of a button or turn of a
knob. A small lcd display would be nice, or some way to display it on
another screen/monitor as I'm trying to figure out a back-up camera
and could display the temp info on that monitor. It's a small 5.5
inch b&w crt display with a few inputs. I'm open to anything. cheap
and easy being impotant as I am both.

thanks,
doug

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
 
D

doug

Jan 1, 1970
0
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
 
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