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OAT wiring - testing?
Posted: Tue Apr 06, 2021 5:12 pm
by Loman
I have grafted on the wires of the supplied OAT sensor to the relevant wires of the iBox PWR connector. As I understand it, OAT green goes to iBox black on pin 4 and OAT red goes to iBox green (TMP) on pin 9. I have used solder sleeves, which are new to me
But how to test my work? Should there be connectivity across these pins? Do I need to apply voltage and measure resistance? Perhaps I should leave well enough alone until the iEFIS system is powered up and just see if it works, but it would be more difficult to fix at that stage.
I notice that there are two other cores in the OAT sensor cable, yellow and black, which are just snipped off.
Re: OAT wiring - testing?
Posted: Tue Apr 27, 2021 9:05 pm
by adamoconnor
Loman wrote: ↑Tue Apr 06, 2021 5:12 pm
I have grafted on the wires of the supplied OAT sensor to the relevant wires of the iBox PWR connector. As I understand it, OAT green goes to iBox black on pin 4 and OAT red goes to iBox green (TMP) on pin 9. I have used solder sleeves, which are new to me
But how to test my work? Should there be connectivity across these pins? Do I need to apply voltage and measure resistance? Perhaps I should leave well enough alone until the iEFIS system is powered up and just see if it works, but it would be more difficult to fix at that stage.
I notice that there are two other cores in the OAT sensor cable, yellow and black, which are just snipped off.
The temp sensor in the OAT probe is technically a "chip" so it won't be as easy as just using a DMM to check. Rainier might be able to chime in, but as long as the connections are secure and don't move - or otherwise the solder in the sleeve has properly flowed, then you should be perfectly okay.
Re: OAT wiring - testing?
Posted: Fri Apr 30, 2021 9:00 am
by rainier
We use the popular LM335 sensors.
We supply them with a small current and they "drop" a voltage which is dependent on temperature. It is easy to test them as follows:
Voltage drop is linear and proportional to temperature in degrees Kelvin with every degree equal to 0.01V.
0 degrees C is 273 degrees Kelvin = 2.73V (32 degrees F)
30 degrees C is 303 degrees Kelvin = 3.03V (86 degrees F)
The iBOX simply measures the voltage with respect to ground at the RDAC.
OAT connecting
Posted: Sun May 08, 2022 7:48 pm
by DKnezacek
I am trying to figure out how to connect my OAT probe to my Vega EMS-1. I can't find any reference to doing this in the manual.
I guess it needs to be connected to one of the analog inputs? That would be the Orange, Green, Gray, or Red/White striped wires?
The other wire would be connected to ground, I'm guessing? Does it need to be connected directly to the engine, or can it be connected to a ground bus?
The probe has one black and one red wire. Does it matter which one is connected to the EMS-1?
Thanks,
Dan Knezacek
Re: OAT wiring - testing?
Posted: Sun May 08, 2022 8:11 pm
by sparxfly
Black to ground, red to input, pullup resisdtor ON, set sensor as LM335 type.
Re: OAT wiring - testing?
Posted: Wed May 11, 2022 8:53 pm
by adamoconnor
sparxfly wrote: ↑Sun May 08, 2022 8:11 pm
Black to ground, red to input, pullup resisdtor ON, set sensor as LM335 type.
Sometimes Green is ground too.
Re: OAT wiring - testing?
Posted: Fri May 13, 2022 2:14 pm
by DKnezacek
So the pullup resistor goes from the input to 5v, or 12v?
Is the resistor directional? There were 3 or 4 resistors that came in the package, are they all the same?
Dan