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sensors and actuators?

Discussion in 'Sensors and Actuators' started by Micki, Apr 19, 2013.

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  1. Micki

    Micki

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    Apr 19, 2013
    I have a very limited knowledge concerning electronics. However, I would like to be able to have a linear solenoid that contracts with current and returns to the previous setting when current is removed. I would like the process to begin when a proximity sensor is activated. I am unsure what type of proximity sensor to use. I believe a magnetic sensor might be to generic for my purposes as I would like to have each application be a dedicated circuit that would work only with its "key". Battery life will be a factor for each activator.

    Any ideas on the availability and practicality of this set up and what type sensors or available?

    Thanks for your assistance.
     
  2. Laplace

    Laplace

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    184
    Apr 4, 2010
    Instead of a linear solenoid have you considered a battery powered gear motor driving a worm gear to achieve the linear displacement? How fast does the motion response need to be? Choosing a sensor might become self-evident once you describe what is it about the "key" that can be sensed.
     
  3. Micki

    Micki

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    Apr 19, 2013
    I am in the preliminary stage of considering the process or processes needed to complete my task. I am not sure at this point the type of end movement is as important at this stage of the process as figuring out if getting a current to that solenoid, motor or whatever is possible and what options I have in completing the circuit with a dedicated “key”.

    example- a "fob" allows a completed circuit in an automobile so that a push button start is possible. I would like something along that lines but on a much smaller

    Any suggestions are appreciated.
     
  4. SPLatMan

    SPLatMan

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    Apr 22, 2013
    Micki,

    The two principle devices for converting electrical power to linear motion are linear actuators and solenoids.

    An LA has a motor and lead screw arrangement. It is relatively slow, has a long-ish stroke and usually is expensive. The cheapest source of LAs is electric car window retrofit kits.

    A solenoid consists of a lump of steel inside a coil, which moves when the coil is powered. It is fast, has a short stroke, costs somewhat less but can consume a lot of power. Electric irrigation valves use solenoids, as an example.

    SPLatMan
    http://splatco.com
     
  5. Micki

    Micki

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    Apr 19, 2013
    Thanks again for the attempt to help me on this. But again... I am not so much interest at this time about the "end" movement, direction or type, but the "beginning" of the process.

    I need the information on the "sensor" and "key" (for lack of a better word) that starts the process. I need to know what types of sensor would work best. Helpful information on the proximity distance for the key and the part or parts needed to transfer that key information into a current that would power the solenoid. At this point the type solenoid or whatever is irrelevant. Once I figure out the best way to get the current moving to where I need it then, I can figure out what type motion I need as a result.

    I used a car "fob" as an example earlier. In that example I am not interested in the cars starter. I am interested in the process that allows for the current to flow to the starter without the physical key being in the ignition. I am interested in that only as a design for a much smaller process.

    Thanks again for your help.
     
  6. Laplace

    Laplace

    1,252
    184
    Apr 4, 2010
    In the absence of any relevant design requirements or intended application information, I would suggest a pocket mirror as the "key" and a solar cell as the sensor. Mount the solar cell at one end of a plastic pipe at least ten cell diameters long. Use the "key" interposed between the sun and the plastic pipe to send a beam of sunshine onto the solar cell. Then use the generated solar current to drive the base of a transistor that powers a relay; use the relay to switch the battery to the solenoid. This approach meets all stated design requirements.
     
  7. Micki

    Micki

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    Apr 19, 2013
    Everybody got to be a comedian! Thanks.
     
  8. SPLatMan

    SPLatMan

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    Apr 22, 2013
    OK, that just penetrated my thick head!

    There are a few technologies for the "key". A car remote is one. Another is an RDIF tag.

    Either way you will need a receiver/decoder, as both work on radio with an encoded "secret message". You may be able to find an RFID receiver that can be pre-programmed to a certain code ... I'm not sure. It would take an hour of two googling to find out.

    One company I know if RFD in California. They make keyfobs and matching receiver, which I believe can be pre-coded. This is product intended for professional use, so you need quite a bit of knowledge to decipher their information though it is quite detailed (we have used their product in our company).

    Either way again, once you have the receiver you will almost certainly need some kind of electronic smarts, i.e. a controller, between the decoder and the actuator. That's where our products come in :cool:

    SPLatMan
    http://splatco.com
     
  9. Micki

    Micki

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    0
    Apr 19, 2013
    Thank you sir. I will do some Google work. Hopefully one day I will be at the point where I can use your product as an interface. Thanks again.
     
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