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How to keep the Ping Sensor warm? — Parallax Forums

How to keep the Ping Sensor warm?

Matthias09Matthias09 Posts: 47
edited 2009-09-03 03:19 in Accessories
Hey guys,

in my desperate trials to make the Ping))) sensor measuring more distant objects, I had a breakthrough today. smile.gif Keeping the sensor warm makes it measuring longer distances, from around 20cm (has to detect a ball) to now 35cm!!

However, I cannot hold my hand all the time on the backside of the sensor, so any idea how I can keep it warm? Basically I just have to put some kind of warming object over the whole backside of the sensor that protects him from the cold air conditioning. Active warmer is not necessary.

Best,

Matthias

Comments

  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-08-27 03:50
    Matthias,

    I'm skeptical about this, but still open-minded. When you held your hand over the backside of the PCB, were you in contact with it? I wonder if it's more of a skin conduction thing than heat. Can you verify your findings by using a blow dryer instead? Also, is it possible that when you had your hand over it that you deflected or shielded it from something closer (which would have registered first)?

    -Phil
  • mikedivmikediv Posts: 825
    edited 2009-08-27 17:49
    I have to agree with Phil I think by holding your hand you might be stabilizing the platform and improving its accuracy.
    If we are wrong and it is in fact the heat you can use a pellitier junction one side cools but the other side heats ,,,if the hair dryer causes interference with air turbulence
    try a 60 watt light bulb keep everyone posted I am very curious
  • Matthias09Matthias09 Posts: 47
    edited 2009-08-30 00:50
    Hey guys,

    I am skeptical too. Background story is: I started to work with these sensors in another office a couple of months ago, there was no a/c and it was always too warm to feel comfortable. Few weeks ago I moved to the new, a/c enabled office and the sensors couldn't detect the whole range of the beam anymore (what they could do before). It took my some time to consider temperature as an option.

    The backside of the sensors is taped with duck tape (or insulating tape), where I applied the sticky side directly on the chips. So when I touch the sensors, I actually only touch the tape, not the sensors themselves. There is nothing around the sensors, they are fixed to an alumina beam with a plastic holder (similar to the one Parallax offers, made of Alumina). The sensor are connected to the SX with an unshielded cable. Might that influence them as well?

    I'll try the light bulbs and, if I can get one, the hair blower and keep you posted!
  • mikedivmikediv Posts: 825
    edited 2009-08-30 00:55
    Mathias who knows that's what testing is for I guess, I was thinking some more about this, I race snowmobiles and I have an air density meter the colder the air the more dens (compact) it is so maybe and this is just my hypothetical
    The cold air being denser would be harder for the ping to "push through" limiting its range ???? I am really curious I only one ping and its embedded in a project that I don't want to pull apart right now but I will keep an eye on this post to see what you come up with
  • kwinnkwinn Posts: 8,697
    edited 2009-08-30 04:48
    I think mikediv may have a point. The speed of sound will vary with the temperature of the air, as will the electrical characteristics and resonant frequency of the transducer.
  • Matthias09Matthias09 Posts: 47
    edited 2009-09-01 02:40
    actually the air speed is dependent from the temperature.

    C_air = 331.5+ (0.6
  • Clock LoopClock Loop Posts: 2,069
    edited 2009-09-02 15:35
    Couldn't you use a parabolic dish of some sort to help increase the range? Just a suggestion. (the NYC metropolitan museum of art has a parabolic mirror that reflects your image and voice when you stand in its sweet spot, if your ever out there, visit this museum)
  • SRLMSRLM Posts: 5,045
    edited 2009-09-03 01:35
    Clock Loop said...
    Couldn't you use a parabolic dish of some sort to help increase the range? Just a suggestion
    I don't think so. The ping times out after a while, so you may get better results within the range but it wouldn't increase the range. Of course, you may be able to reprogram the ping if you're so inclined.
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2009-09-03 02:03
    I tiried the parabolic reflector idea. Unfortunately it doesn't work, because the Ping))) picks up the first reflection from the reflector itself, and that's it: no more waiting for a second reflection.

    -Phil
  • kwinnkwinn Posts: 8,697
    edited 2009-09-03 03:19
    If you want to warm the Ping))) try using a resistor as a heating element. A 47ohm resistor will be just under 1/4W with 3.3V applied.
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