TI LDC1000 inductance-to-digital converter

in components by the machinegeek | 16 comments

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Manuel Garbe draws attention to a new inductance-to-digital converter chip known as the LDC1000 from TI. This should eliminate the need for Hall effect sensors and magnets, providing contactless sensing with immunity to non-conductive interferences.

Here’s a link to a good explanatory article from EDN.

The datasheet can be downloaded from TI.

Via the contact form.

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Comments

  1. jfsimon says:

    You can get a small USB evaluation board to play around with it for $4 on the TI e-store, if you use a coupon code that someone gave on thee EEVblog forum. (The coupon also works for other items in the store…)

  2. mossmann says:

    I think this will be my next guitar pickup.

  3. Paul says:

    Can this be upscaled to a handheld metal detector. I have the EVM on order, so I will try it .
    the supply current looks low but that is without the coil. I have tried to find better docs for this, so does anyone know the MAX current this IC will supply to a coil.?
    looks like a software defined metal detector.

  4. hli says:

    I got my EVM, and played around a little bit with it: http://blog.hendriklipka.de/archives/2013/09/ldc1000_test.html

    This sensor is intended for small ranges only (several millimeters), so it won’t work as general purpose metal detector.

  5. Paul says:

    Thanks, I see on the TI site that they adding to the range of these ICs so it may be possible to make a bigger detector. Did you try any other coils or just use the EVM PCB.

  6. hli says:

    Just the coil on the EVM, I did not come around to create another one. The WEBench tool unfortunately seems to work for PCB coils only. And I’m not really in the mood to create a coild with 50 turns or so on a PCB…

  7. hli says:

    Regarding the metal detector question: I got some feedback from TI about my article. One of their product experts told me that, for a more general metal detector, one either needs a larger coil or should add a ferrite backing to it. So I did some more experiments, though not with a larger coil (so the results are not as good as they should be). I need to go into the coil winding business…

  8. Paul says:

    thanks Hli, the depth a detector can see is usually determined, in some degree, by the coil dia. rule of thumb, depth = 1.5 coil dia. This does not apply to all detectors ie the Two Box detector which has a large virtual coil, not the actual coil dia.
    I have made a quickie test coil by wrapping wire around a 90mm (3.5″)plastic pipe, found beside road. The coil has taps every ten turns so I can play with different inductances and frequencies. The large dia also means it will be easy to try some ferrites.
    I”should” hook up my DDS and check for the self resonate frequencies but I’ll probably just wait and see what happens with the LDC1000 .
    Been spying on the progress of my package and it is due to be delivered tomorrow.

  9. Spixycat says:

    Very interesting to follow this guys, using this for a metal detector.

    Would be interesting to use this detector in combination with a ie Android Phone, using the IOIO

    And @Paul (previous posting) what do you exactly mean by different ferrites? Normally a coil is wounded around a ferrite, like an old school radio antenna?

  10. Paul says:

    Ferrites come in a variety of sizes, not just lenght but in the ferrite granular size as well. This means that different ferrite compounds are better for some frequencies and as the LDC can operate up to 5MHz there will be some room for exprrimenting. I have noticed the EVM software won’t let me above 30KHz, and as I’m still working on another type of metal detector, and trying to receive some Phonesats etc some projects have to wait. I’m looking at a 89C2051 board I have or an arduino to interface rather than use the TI micro on the EVM

  11. Paul says:

    I was just looking at some circuits copied from $800+ metal detectors and all I could see was some quaint 80′s tech. Full of 555 timers, analog switches and comparators,nearly pure analog, and thought to myself I could do better with a (now) cheap 32bit micro. The EVM does come with a 32bit micro doesn’t it. I may just have to invest a little time and come to grips with this one.

  12. Paul says:

    EVM is 16bit, 25MHz still good enough.

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