how do to make and design the distance detector device...

Discussion in 'General Electronics Chat' started by aly_chere, Feb 29, 2008.

  1. aly_chere

    Thread Starter New Member

    Feb 29, 2008
    6
    0
    please.....in need your help...here the refference that i got..
     
  2. mik3ca

    Active Member

    Feb 11, 2007
    189
    0
    search for an AM radio schematic.

    A radio can help detect distance. Just make a transmitter and a receiver. Add a potentiometer somewhere on the transmitter that can reduce the transmitter power. Then you can use this dial (potentiometer) to determine the maximum distance between the transmitter and the receiver.
     
  3. h.d

    Active Member

    Oct 22, 2007
    150
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    you can use the encoder with IR transimtter reciever
     
  4. hgmjr

    Moderator

    Jan 28, 2005
    9,030
    214
    What is the range of distances you need to measure?

    hgmjr
     
  5. aly_chere

    Thread Starter New Member

    Feb 29, 2008
    6
    0
    actually this is my project to do, what happen now i need to use some ligth source and also silicon photodiode. so , i need ur help to discuss about how to design this circuit due to meke this circuit operate. how about its amplifiers and also thr reesistor?...please..this is my project refference

    www.freepatentsonline.com/4436418.html
     
  6. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    That's a confusing idea.. it doesn't seem too practical, although it claims simplicity and ease of manufacture.

    I think you need to read the patent fully to understand the concept, then try to replicate the solution via obtainable parts. The lightsource and photodiode are the least of your worries, especially without understanding the overall concept.

    From what I gather, you need a collimated source to be reflected from an object. The light returns, but somehow gets blocked by a shade. Apparently this shade is movable, which makes me think that there is a subsystem which keeps the light from striking the photodiode(s). The position of this shade can be used to determine, through triangulation, the distance from the reflecting target to the unit itself.

    This patent is quite old, so I would tend to stay clear of this particular idea. I designed a 2D distance measurement system a couple of years ago that used a line laser and a 1M pixel CMOS image sensor. It only took a couple months to design and worked quite well. Another idea is to look into position sensitive detectors (PSDs) to do this. Another method is time-of-flight, which requires an extremely fast clock/counter or a very precise phase detector.

    Steve
     
  7. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    The patent isn't all that complicated, just a little clunky.

    It slides a shade across some kind of photo-sensor. The position of the shade, when it blocks the light, is used to calculate distance to the illuminated object.

    Some kind of long, skinny photo diode would be needed.

    Also would need a motor to move the shade, and some kind of sensor to generate a value proportional to the shade position.

    I think the same principle could work with a CCD from a fax machine or scanner. No shade would be needed as the position could be read from the CCD directly. Still clunky, though.
     
  8. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    I found it confusing because they didn't really mention much about the shade, the rest is fairly simple.
     
  9. thingmaker3

    Retired Moderator

    May 16, 2005
    5,072
    6
    One of the big problems with patent documents (for me anyway) is they are written by lawyers. I sort of have to read them "sideways" to squeeze out the useful bits. It can indeed be frustrating.
     
  10. aly_chere

    Thread Starter New Member

    Feb 29, 2008
    6
    0
    hi steve, emm..yap this project is quite to old, but i still want to know how about the kind of silicon photodiode i must used it and also the circuit that worked for this project, n then firstly, i don't get idea to combined with circuit
    and the part 6a..(refer to the refference), and also how about the part 7. emm...this project using mto dc or not?..i dn;t undstand it...emm...i'm interesting from your project which is you were designed. may i know the details with your project, include all the circuit.
     
  11. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    As we mentioned, you need to find a long and narrow photodiode. Use a laser pointer for the best results, since they're fairly easy to make a tight beam (collimated). The light reflects from a target, then returns to find the surface of the photodiode. You need to control the position of the shade via a microcontroller or a carefully designed analog controller. Something like a Proportional-Integral controller would work best. The shade would probably be best driven via a 'leadscrew' type drive (small diameter leadscrew) on some sort of dovetail or linear bushing. The position, calculated from a linear position sensor (potentiometer-type, lvds, etc.) or from a rotary optical encoder fixed onto your leadscrew shaft. You will need to concern yourself with backlash of the assembly, or you will get error in your position.

    For my old design, it was a matter of manufacturing more than circuit design. All I did was make a power supply, add some memory, provide an interface to a host controller, slap on an image sensor and an FPGA. If you want a PCB layout, I can give you gerbers and drill drawings for manufacturing. I would need to generate a bill of materials too, since you cannot just go substituting different parts.

    Two notes: if you want to build, decouple the prom with capacitors, plus, you don't need the I2C interface part. I was planning on controlling a small mirror via another PCB stacked on top, with some bimorph piezo actuators.



    Goodluck,

    Steve

    I snapped a pic of it, it's old and dusty by now. I didn't include the picture of the lens, but I think I have the part number I used somewhere.
     
  12. aly_chere

    Thread Starter New Member

    Feb 29, 2008
    6
    0
    thanks all information..but i'm still quite not understand about your design..so..lets me know further this design, may be we can discuss about this using yahoo messenger...i'm really appreciated...your project is so interesting for me..please.....this is my emails....aly_chere@yahoo.com.my...emm..btw..thanks for helping.



    :)
     
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