Need an idea for a really tiny receiver

Discussion in 'Wireless & RF Design' started by DickCappels, Nov 13, 2008.

  1. DickCappels

    Thread Starter Moderator

    Aug 21, 2008
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    I need and idea for a very tiny receiver.

    Max. board size: 6 mm x 12 mm
    An antenna can extend a cm or two past the end of the board.
    Max. component height: about 4 mm
    Power supply: 1.5 volt
    Output: Source or sink 140 ma peak to drive a small motor from 1.5V.
    Range: 3 meters was requested, but I think 1 meter will be ok.

    Ultrasound and IR don't seem to be good candidates for practical reasons, leaving RF. I think this is too small for a Bluetooth module.

    This is a one-off for a magician, so the parts can be hand-selected. The transmitter can be anything as long as he can hide it in his clothing, so that's not the worry at the moment.

    Anybody have any clever ideas?

    Thank you in advance.
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    I built a gag gift that was remotely activated from about 10 feet. I used the receiver and transmitter from one of those tiny ZipZap cars http://www.radioshack.com/uc/index.jsp?page=researchLibraryArticle&articleUrl=../graphics/uc/rsk/ResearchLibrary/BuyersGuides/research/zipzaps.html that they were almost giving away several years age. The receiver is very tiny, and runs off 1.5v. It has 4 outputs, though you will need to make transistor level shifters. What are you trying to drive with it?

    Ken
     
    Last edited: Nov 13, 2008
  3. DickCappels

    Thread Starter Moderator

    Aug 21, 2008
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    Wow, KMoffett, that looks pretty good. do you know how large the receiver module is?
     
  4. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    A little bigger than I remember: 21mm x 17mm.

    Ken
     
  5. SgtWookie

    Expert

    Jul 17, 2007
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    Ever seen a ZN414 or MK484? They're an AM receiver in a TO-92 package. You still need a few external components, but if you're clever you can make them pretty small.

    Can't remember who made the original MK484 at the moment, but I think you can still get the ZN414 from Philmore.
    Here's a link to a Philmore catalog, the part is on the upper left corner of the 4th page:
    http://www.calcentron.com/PDF_Documents/philmore_pdf/philmore_d-i-y_component_parts.pdf
    Part# 86-1007
    Calcentron's order form is here:
    https://www.calcentron.com/secure/quoteorder_form.htm

    I attached a datasheet to give you some ideas.
     
  6. DickCappels

    Thread Starter Moderator

    Aug 21, 2008
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    Great minds work alike.

    I am trying some ideas with an MK484, a modern day clone of the ZN414. Its great - lots of gain in a tiny package, not may external components, and it should be easy to use the "AGC" voltage to drive an output transistor, all in a single TO-92. The disadvantages are with the antenna -very low antenna efficiency (0.1 meter antenna for 300 m wavelength) and if I use an inductive antenna to increase sensitivity and get some selectivity, then it becomes directional (no room to mount two of them at 90 degrees).

    I will continue to look at the ZN414/MK484, but I was hoping for something at a higher frequency, and maybe even a small enough circuit already designed with antenna in/ motor drive out.

    BTW, I didn't know about Calcentron. I see that I need to spend some time on their site.
     
    Last edited: Nov 14, 2008
  7. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    I assume you have looked at the micro RC sites. In case not, here is one site that seems to have a good selection: http://www.cloud9rc.com/indoorflying.asp

    The Global Cirrus Micro Joule receiver is about halfway down the page. It is 7.9X28X8.4 mm including the four servo sockets. It is a bit bigger than your maximum, but I am assuming the receiver component per se is considerably smaller than those dimensions. Unfortunately, I don't have one to check part numbers on.

    John
     
  8. DickCappels

    Thread Starter Moderator

    Aug 21, 2008
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    Those receivers are really cute! But OUCH! the price tag. One thing is for sure, the 0805 size passives I was planning to use are very large and out of date - something that hadn't seemed a problem until now. Back to e-bay for a selection of even smaller parts.
     
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