Vibration Sensor
Tony11
Posts: 41
Hi,
What kind of vibration sensor should I go with to read A Dryer Machine running. I want this vibration sensor to know if
the Dryer is Vibrating or is off. So if the Dryer is on and Vibrating, it would make A led turn on with the BASIC STAMP or PROPELLER turn on.
What kind of vibration sensor should I go with to read A Dryer Machine running. I want this vibration sensor to know if
the Dryer is Vibrating or is off. So if the Dryer is on and Vibrating, it would make A led turn on with the BASIC STAMP or PROPELLER turn on.
Comments
Hi Tony,
Could you clarify this request a little? Are you trying to indicate when the dryer is on or off by sensing vibration? Or are you interested in indicating a vibrational problem when the dryer is running?
If you simply want to indicate when the dryer is on or off, there might be other, possibly better, ways of sensing on/off instead of vibration. For example, there might be a way to sense when the motor is running via Hall effect switches, LED + photosensor, etc.
So if you could restate what you're trying to do, it might help a bit.
But, as a quick pointer, there is the Vibra Tab.
http://www.parallax.com/StoreSearchResults/tabid/768/txtSearch/vibratab/List/0/SortField/4/ProductID/89/Default.aspx
Frequently a project needs to turn when it is picked up. In one of our projects we needed to log whether the object was being carried around as opposed to sitting on a shelf. The vibratab is a good option, but it is awkward for miniaturization. Accellerometers AFAIK are relatively pricey, I think. I know there is one in the TI Chronos, so it can't be too expensive, at least in the quantities that TI can tap into. I'm curious what others have used for this purpose.
I've obtained clever micro vibration sensors from http://www.sensolute.com/. These the size of 1210 chip resistors, and consist of a tiny stainless steel ball rolliing around in an interior cavity with gold contacts. A switch, basically, but suited for vibration and not static position. They are very sensitive. For a project we are thinking about buying a whole reel, at about $1 each. But what are the alternatives?
It has several modes, including "tap" and "shake" detection, but its internal low-pass filtering may limit its usefulness for detecting small vibrations.
-Phil
What I am trying to do is, when the dryer is on and vibrating the sensor would pick this up and make the led light up. When the dryer is off and led is off.
So I would use A sensor, then the (Basic Stamp or Propeller), then A led.
What sensor would work good for me and the code.
code that is on the page. I had to hit the tab with my hand to make it work. I would like to just set the tab on the dryer and it turn on the led. Why can't it be that easy.
You might need to mechanically "tune" the Vibra Tab to resonate at a vibration that the dryer is generating. To do this, you might need to tape a tiny weight near the end and experiment with your dryer until you get things tuned just right. The Vibra Tab is effectively a mass on a spring, and since you can't really change the springiness of the Tab body, your only way of tuning it is to add mass. As you increase the mass, the resonant or peak vibration frequency will go down. In other words, as you add mass, you will cause the Tab to "listen" better for deeper vibrations.
I suppose another method might be to try a microphone and filter it to pass only deep, low sounds.
As an alternative, consider sticking a magnet on the rotating drum or some other rotating component and use a Hall Effect switch to pick up the rotation, then run wires to the top of your dryer to power the LED.
Just a thought.
Tony, you may need an amplifier for the vibratab to bring the small signal up to the 1 to 2 V input threshold of the Stamp or Prop.
Another possibility is to use two Stamp or Prop pins: One is an output with a high Ω resistor over to one side of the vibratab, and from there a wire or low Ω resistor goes to the second Stamp or Prop pin as an input. The other side of the vibratab to ground. The vibratab is a capacitor, but a special one with the capacity to generate its own voltage. The program repeatedly reads the input and sets the output to the inverse of that. The effect is to keep the vibratab charged up to the input threshold of the Stamp or Prop. The Prop is very well suited to that and has some built in help for that sort of thing, effectively a sigma-delta analog to digital converter. If the tab is not vibrating, the output pin should split 50:50 between high and low. But if the tab vibrates, the high:low ratio follows suit and the Prop can detect and analyze the frequency and amplitude. I'm not sure how well it could be made to work on the Stamp, but I guess that it could be well enough to light the LED.
(Piezo Film Vibra Tab Mass) and led. So when the Tab hit and vibrating it will make the led, turn on.
Thank you people for helping, with the sensor......and the Thread.......
I suppose you might be able to take the output of the Vibra Tab and operate some kind of transistor circuit with it. If you have an oscilloscope, hook it up to your Vibra Tab and mount the Tab on the dryer, then read what sort of signals are coming out of the Tab during dryer operation. You probably want to "clamp" the output voltage of the Tab so it won't exceed 5 volts or so, since the output of the Tab, when bumped, could far exceed voltage levels that are safe for electronic components - use a zener diode for voltage clamping. I think the Vibra Tab's product page has a suggestion for what diode to use.
http://www.parallax.com/Store/Components/Transistors/tabid/155/List/0/SortField/4/ProductID/200/Default.aspx?txtSearch=vibra+tab
If the Tab's signals are weak, you might be able to amplify them as Tracy Allen suggested, then feed the amplified signal into another transistor that switches the LED on and off. With a capacitor and some resistors, you can probably rig up some kind of crude timer so that once the Vibra Tab emits a signal, it will keep the LED on for enough time so that it's visible.
Again, I think it will take some experimentation to get everything just right. Bear in mind that, by sensing vibration, you might also pick up the vibration of other things - people walking, the washing machine on spin cycle, etc.
I don't know how to design transistor circuits, so maybe somebody else can provide a suggestion or two.
hope that helps,
Sounds like a good idea to me.
Consider a 555 timer chip operated in monostable mode. See for example:
http://www.doctronics.co.uk/555.htm#monostable
I'm working on a project similar to the one described by the original poster, but with some more complicated logic, and listening to a blower, not a dryer. And I don't have any VibraTab sensors, just a pile of surplus piezo disks that I picked up somewhere or other. But I did attach some wires to one of my piezo discs and attached the whole thing to the blower and my oscilloscope, and it looked like the signal the disk was outputting in the neighborhood of 2.5 millivolts, on average, while the blower was running. So, yes, it will need some amplification before I can use it. However, when bumped or tapped on, the voltage jumps to several volts or more, so it will definitely need to be clamped to avoid frying whatever is monitoring the sensor. (I was also picking up a huge amount of 60Hz hum, so I actually tried this twice, once with unshielded wires, and once with shielded. The shielded version seemed to "look" better on my 'scope, but I'm still concerned that I may have to filter out some of the hum somehow... or shield the heck out of the analog portion of the circuit. I live near an electrical substation...)
I havent't quite decided yet how I'm going to amplify the signal (I'm guessing some kind of op amp), and/or how I'm going to use the resulting signal as an input... simple on/off detection might be sufficient, but if I could make it detect the difference between high speed and low speed on the blower (i.e. high volume/low volume, a.k.a. higher voltage/lower voltage), that would offer some interesting possibilities too... so an A/D converter might be useful. I'll probably just have to fiddle with it to see what's practical.
Incidentally, in my case I can't tamper with the blower equipment in any way, so I have to use some kind of passive sensor: vibration, microphone, or possibly current draw. I can't disassemble the unit and add magnets, masses, or anything else clever. And for that matter, I live in an apartment, so I wouldn't be able to do that to my dryer, either!
I'm still looking for good ideas to help get this project off the ground, so if anyone has suggestions for me or the original poster, please post!
Welcome to the forums!
If the vibrations are at a specific frequency or at a frequencies that do not overlap the interference, then filtering in hardware or software could help suppress the AC hum pickup. But it is always best to eliminate it at the source with shielding and strategic placement of the sensor away from the hum source, electric and magnetic fields from the blower and the substation. With an oscilloscope, you can ballpark the frequencies and amplitudes of the signals and the noise.
Are you interfacing to the Stamp, or Propeller, or something else?
Is this the easy way to make the (Piezo Film Tab Mass) work, with out using the Propeller or Stamp?