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Thread: Cheap Sensors

  1. #1
    Nothing good comes cheap, blah blah blah. I have to imagine that there are very cheap alternatives to buying sensors from the main motorsports sensor companies or big DAQ companies. Typically the guts of any sensor is based on individual components that are dirt cheap. Granted, that purpose built sensor will be more accurate, have a faster time constant, or more resolution, but could a team on a budget not get usable data for a handful of change?

    Our team could only afford 2 linear pots from the suspension, and ran them diagonally opposed to estimate 4 wheel data. A few years ago, Claude asked, "how many wheels do you have? Then why do you only have 2 poh-tench-ee-oh meters?" He then proceeded to talk about a team that made a usable system with cheap radio shack rotary pots and told us that budget should never be an excuse, because you can almost always come up with a clever solution on the cheap.

    For example: Cheap chinese eBay IR guns. Can they not be taken apart, repackaged and become IR tire temp sensors? They have to have some voltage output that could be read.

    Wheel speed sensors are relatively expensive for what they are. Could those not be replaced by simple hall effect PCB's?
    Stephen Rodi
    University of Central Florida
    Formula Team Leader

  2. #2
    Oh absolutely Stephen!

    Cheap, homemade or improvised sensors and transducers can work really well if they are carefully calibrated and installed with tender loving care.

    Now maybe they won't last 300,000 road miles, or work over aerospace temperature ranges, or survive 50G shock and vibration, or submersion to 200 feet.

    But they can work wonderfully well over a short intensive do it yourself on a shoe string R&D effort.

    In the end, it is what you do with the data that really counts.
    Cheers, Tony

  3. #3
    You can get Melexis IR temp sensors for ~$12 on digikey. These can be configured to output a PWM signal. Run this through a low-pass filter (1 resistor and 1 capacitor) and you have a voltage output with relation to temp. They also have an I2C interface, so if you have a competent EE/CE or 2, it's really simple to make an IR to CAN device using a microcontroller. We're running 3 of these on each wheel and logging the data via CAN to a DL1. Overall it'll cost you about $50 in parts per wheel compared to ~$200 per individual IR sensor from somewhere like Texense.

    Mark Schaumburg
    Head of Electronics and Data Acquisition (2011-2013)
    Mizzou Racing
    University of Missouri - Columbia

  4. #4
    Exactly. If you have people who can read (and make sense of) the datasheets of sensors on Digikey / Mouser / Etc., then you can find cheap industrial alternatives.

    Just keep in mind that a lot of industrial sensors are meant to be powered by 24vdc, check the power requirements extra carefully and you will be fine.

    Northwestern Formula Racing Alum
    Head Engineer, Frame/Suspension 2006-2009

    My '73 Saab 99 Road Race Build

  5. #5
    Senior Member
    Join Date
    Mar 2008
    Palo Alto, CA
    Sparkfun electronics all day long.
    Formula SAE: When you just can't get rid of a girlfriend.

  6. #6
    I'm still waiting for a team to show up with the junkyard sourced Cadillac night vision cameras Bill Cobb has mentioned a couple times.

  7. #7
    Originally posted by Zac:
    I'm still waiting for a team to show up with the junkyard sourced Cadillac night vision cameras Bill Cobb has mentioned a couple times.
    ...In all seriousness, Baja teams have talked about it. They want it for a rear view camera.
    Kettering University Vehicle Dynamics
    Formula SAE 2010 - 2015
    Clean Snowmobile Powertrain 2012 - 2015

    Boogityland 2015 - Present

  8. #8
    Home made daq is going save you a ton of money and would be a neat project. What you save in $$$$ you will be paying for with time and headaches though. Totally possible and cool in scope of fsae none the less.

  9. #9
    This what I have learnt in terms of cheap sensors

    1. What is cheapo is not good. What is good is no cheap.

    2. Three goals: Quick (delivery), good (quality), cheap. Pick two.

    3. Worth to pay a bit more for the possibility to be in contact with the sensors customer support service and ask any question and tips and trick you want.

    4. Beware of manufacturing copyright infringement (Did I say Asia?). If you do not want your intellectual property to be stolen, do not stole others rights. What goes around comes around. Do not do to others what you do not want others to do to you.
    Claude Rouelle
    OptimumG president
    Vehicle Dynamics & Race Car Engineering
    Training / Consulting / Simulation Software
    FS & FSAE design judge USA / Canada / UK / Germany / Spain / Italy / China / Brazil / Australia

  10. #10
    Senior Member
    Join Date
    Aug 2011
    Brisbane, Australia
    In terms of cheap position and pressure sensors we're about to have a crack at using Honeywell RTY's for suspension position and steered angle and SSI P51 series pressure sensors for fuel pressure and both brake circuits. When I've actually had some experience with them I'll post here and let people know how they went, but on paper both look good.

    Honeywell's should stand up real well. Weather sealed sensor with an amp termination and they're hall effect rather than resistive so no friction on a resistive strip to fuck shit up. Hard to justify couple hundred dollar linear pots when we can get these at 70AUD(ish) each.

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