How to use this pressure sensor?

Thread Starter

LikeTheSandwich

Joined Feb 22, 2021
164
I have a "Tacklife" brand portable tire inflator but the electronics seem to have died. I'm looking to replace the control electronics with an Arduino microcontroller of some kind. Controlling the pump motor is no problem, but how do I use this pressure sensor? I can't seem to find any data sheets online. Can someone point me to a data sheet so I can write some custom code for this? Thanks!
 

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LowQCab

Joined Nov 6, 2012
4,309
Anything that comes under the category of "Portable-Tire-Inflator"
is an "emergency-use" only device.
They over-heat easily, and wear-out very fast.

They are "throw-away" devices, when they stop working, You throw them in the trash and get a new one.

You don't want it to fail when You really need it on the side of the road.

No "Pressure-Sensing" is necessary, but Temperature-Sensing could be a bonus.
What You have provided a picture of is a "Printed-Circuit Switch Contact".
The fact that it is not attached to the Pressure-Diaphragm that operates it means that it is trash.
Maybe You could just solder the 2 wires together and call it done.
Maybe the Pump will then work.

These types of Compressors are designed to be used only with constant attention from the operator,
so this makes any "Automatic-Controls" a bad idea, ( excepting a Fuse and a Thermal-Circuit-Breaker ).
Also, most of them are only rated for ~10-minutes of
continuous use before they self-destruct by melting in to a puddle of goo.

I have the "Pittsburgh" brand pump from Harbor-Freight, and use it regularly,
it still works surprisingly well after ~3+ years of occasional use.
And, it's fast, ( relatively speaking of course ).
Rating/Comparison
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Thread Starter

LikeTheSandwich

Joined Feb 22, 2021
164
It wasn't attached because I removed it for pictures.

Yeah it definitely overheats bad, but if I can figure out how to use it then I could probably fix it for basically free with parts I have. Otherwise I just have to install a switch and carefully monitor it which would be a pain.
 

Jon Chandler

Joined Jun 12, 2008
1,099
Is this circuit board mounted in a cavity with a hose connection or fixed up against a hose? The configuration looks like a Whetstone bridge configuration of a (full-bridge) strain gauge. If it's mounted in a cavity with pump pressure on one side, it would act as a diaphragm – pressure deflects the diaphragm and the strain gauge measures that deflection.

The four wires coming off the board would connect to points A–D in the diagram. If you measure the resistance between each of the wires, you'll measure the value of each resistor or the value of 2 resistors in series. Strain gauges are typically 120 ohms or 360 ohms.

Wheatstone-bridge-Updated.png
 

Jon Chandler

Joined Jun 12, 2008
1,099
Yes. I believe my description is correct.

Do some research on Whetstone bridge sensors. As shown in the diagram above, you'll have to supply excitation voltage between A and C, and measure the small output voltage between B and D. This will require amplification to feed into the Arduino ADC.

I believe there are some cheap modules available to take care of excitation and amplification.

As far as calibration, you'll have to compare output voltage vs air pressure.
 
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