Digital Multi-point Thermometer

[gary miller]

Gene---
Good insight, Gene. This should make multi-temperature montoring feasable
at minimum cost. One limitation you mention is the upper limit of about 130
degrees and many of the functions that we would like to monitor don't get
interesting until well above that. Wouldn't it be possible to put an
appropriate size resistor in series with the thermistor to allow for higher
temperatures with a simple constant added to the dial number (ie, +100
degrees)?.
Gary
North Bend, Oregon Coast

> -- [ From: Eugene Fisher * EMC.Ver #3.1a PRODIGY ] --
>
> There have been tons of questions about temperatures on the GMC motor
> home. It seems that we are always asking what is the heat rise of the
> Refer, the engine
> compartment, the batteries, the transmission, etc. I have often
> wondered while driving down the road if my wheel bearings were getting
> hot, were the brakes hot?
> did I hear a strange noise back by the generator, was something getting
> hot there , was I over charging a battery on a hot day. I wanted a
> multi-point thermometer
> that I could switch from the drivers seat that was inexpensive.
> Accuracy of plus or minus a few degrees is ok with me since I am looking
> for large changes of
> temperature.
>
>
> I have modified a dual readout thermometer from Radio shack that costs
> nine dollars to Twenty five dollars. The thermometers store the max and
> min temperatures
> and these reading can be viewed by pushing a readout button. They even
> have one that will give voice readings every hour and will give a vocal
> warning if the
> temperature goes over a set point. I have modified the instrument so
> that the two channels are fed by two external 6 position switches
> which are connected to 12
> thermistor sensors that I also manufactured. The Sensors cost $2 each.
> The thermometers have the advantage of operating from internal batteries
> so there are no
> ground loop or noisy power supply problems. The unit shown above is the
> one I will use in my GMC.
> All for less than the cost of dinner.
>
> Take a look on my web page for details.
>
> Gene 76Palm Beach /Or/CA
>
> GMC Technical Information
> http://www.california.com/~eagle/

 

[roger black]

OK, Mr. Wizard,
That's what I was trying to do without the switch. You answered a lot of my
questions and now I know how to set up and protect the wiring end of the
thermistor. The pics were/are very good. Now for my questions:
1. Want to get directions on using lights instead of the meters
2. Thermistor for yellow caution light when temp reaches certain point and
then another for red light when temp is exceeding normal.
3. How do I find the thermistors for different temps or how to figure their
temp ratings? Can they be mounted together as one unit but wired
separately?
4. Are there thermistors with two set temps on one? I.E. three wire ones.
5. How can I wire in a large separate red light to illuminate when any of
the small ones come on?

This should keep you busy for a while but do not fear, I will have other
questions.

Thanks,
Roger

 

[wayne newland]

Gene

If we used this, would we need the Digipanel?

Wayne Newland

> Gene---
> Good insight, Gene. This should make multi-temperature montoring feasable
> at minimum cost. One limitation you mention is the upper limit of about 130
> degrees and many of the functions that we would like to monitor don't get
> interesting until well above that. Wouldn't it be possible to put an
> appropriate size resistor in series with the thermistor to allow for higher
> temperatures with a simple constant added to the dial number (ie, +100
> degrees)?.
> Gary
> North Bend, Oregon Coast
>

>
> > -- [ From: Eugene Fisher * EMC.Ver #3.1a PRODIGY ] --
> >
> > There have been tons of questions about temperatures on the GMC motor
> > home. It seems that we are always asking what is the heat rise of the
> > Refer, the engine
> > compartment, the batteries, the transmission, etc. I have often
> > wondered while driving down the road if my wheel bearings were getting
> > hot, were the brakes hot?
> > did I hear a strange noise back by the generator, was something getting
> > hot there , was I over charging a battery on a hot day. I wanted a
> > multi-point thermometer
> > that I could switch from the drivers seat that was inexpensive.
> > Accuracy of plus or minus a few degrees is ok with me since I am looking
> > for large changes of
> > temperature.
> >
> >
> > I have modified a dual readout thermometer from Radio shack that costs
> > nine dollars to Twenty five dollars. The thermometers store the max and
> > min temperatures
> > and these reading can be viewed by pushing a readout button. They even
> > have one that will give voice readings every hour and will give a vocal
> > warning if the
> > temperature goes over a set point. I have modified the instrument so
> > that the two channels are fed by two external 6 position switches
> > which are connected to 12
> > thermistor sensors that I also manufactured. The Sensors cost $2 each.
> > The thermometers have the advantage of operating from internal batteries
> > so there are no
> > ground loop or noisy power supply problems. The unit shown above is the
> > one I will use in my GMC.
> > All for less than the cost of dinner.
> >
> > Take a look on my web page for details.
> >
> > Gene 76Palm Beach /Or/CA
> >
> > GMC Technical Information
> > http://www.california.com/~eagle/