is there any way to wire up a light to come on @ 1100 degrees. I'd rather not melt my motor.

thanks

 

Your fine untill about 1200. You can get some pricy Nexus guages and their face will turn a color at a set parameter.

 

Easiest way is to get a gauge/monitor that's programmable. I use a SPA digital EGT/boost gauge that's programmable and has lights for high EGT and boost.



The lights are actually on the gauge itself, the red thing next to the gauge is the button to program/recall. Oh, the SPA's also have the ability to hook up to an external source (ie. extra light, buzzer, etc.) and you can program those external high boost/EGT alarms independently.

 

i like my gauges can i just wire a light

 

Nope, not that easy.

 

i assume that the pyrometer works off of voltage.....so........if i could find out the voltage of 1200 degrees and get a light to come on at that voltage. bada bing bada boom.......right

 

exactly what i was thinking!
now the trick is to tap you thermo wires at the sensor and hook a multi meter to the taps and put the meter in the cab and go for a rip. would more than likely need a potentiometer inline with the light and adjust it to send the current through the pot to the light when it gets to that voltage. heck why not set it up similar to the fuel presure light?

 

potentiometer--- what in the gods name is this

 

it is similar to a reostat/dimmer ****.

 

could you maybe walk me through on what i need.........i have the concept but i dont know much about small electrical dodads. i deal with the higher voltages.

thanks

 

Not gonna happen.

Thermocouples put off a very tiny mV signal that you have to compare to ground in order to measure resistance between the two.

Not as simple as just waiting for a voltage.

 

any ideas???

 

If you tap into the wires for the pyro you might mess up the accuracy of it. A thermal couple (which is what goes into your exhaust to measure temp) works off of two dissimilar metals. By adding another wire you might create more resistance or another thermal couple at that point thus throwing off your measurements.

But to answer your questions, if you looking for 1200 deg, I believe the thermal couple used for our pyrometers are K types, these are good for about 41uV/deg C. So…..

1200 F = 648.8889 C. 648.8889 * .000041 = .26604 volts.

So I think you would be looking for .26604 volts to equal your 1200 deg F. Now you would need to make a little circuit to amplify the .26 volts to something to power an LED. An Op-amp would do the trick I think. Probably use an LED that powers from a 5v source so you don’t have to amplify the signal so much.

By far the easiest solution would be to use a gauge that already has a relay output or transistor output and just hook an LED to it.

Good Luck..

 

where could one find this voltage amplifier

 

Thermocouples generate an open circuit voltage based on a temperature differential between the twisted wires and temperature at the open wires. The open ended wire voltage is very small and susceptible to loading so buffer amplifiers for each wire and a differential amplifier designed for full scale range would need to be designed. An adjustable schmitt trigger comparator designed to the set-point value and connected to an LED would work. But this will take some design work and testing for the specific gauge set-up you have.

It is not as simple as a variable resistor circuit or simpe op-amp...

Ken