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  • TomTechTod commented on TomTechTod's instructable Ultrasmall Ultrastable DIY UHF Spy Bug3 months ago
    Ultrasmall Ultrastable DIY UHF Spy Bug

    This one is much more stable, insensitive to touching the antenna or moving it around. The antenna is also much shorter.

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  • TomTechTod's instructable Ultrasmall Ultrastable DIY UHF Spy Bug's weekly stats: 3 months ago
    • Ultrasmall Ultrastable DIY UHF Spy Bug
      1,317 views
      10 favorites
      2 comments
    • Coilgun SGP33 - Full Building and Test Instructions
      205 views
      4 favorites
      0 comments
  • TomTechTod commented on TomTechTod's instructable Tiny UHF Tracker Transmitter5 months ago
    Tiny UHF Tracker Transmitter

    For RF circuits, everything that influences the oscillation frequency should be NPO.

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  • TomTechTod commented on TomTechTod's instructable Tiny UHF Tracker Transmitter5 months ago
    Tiny UHF Tracker Transmitter

    No need to tune anything if using component values from the schematic. If you change the SAW resonator you will need to reajust some values as I described.

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  • TomTechTod commented on TomTechTod's instructable Tiny UHF Tracker Transmitter8 months ago
    Tiny UHF Tracker Transmitter

    Wow that's some distance. For the antenna other conductive material could be used too, sure, like copper tape for example. You only need one antenna. The receiver antenna is pretty big, I dont know if you want to walk around with this on a regular basis though. The only advantage is its low tech, small and inexpensive

    Ok, so I just did a test and removed the antenna and left only the receiver dongle and attenuator connected. The range drops to about 10m max. The signal gets considerably stronger depending on distance to the transmitter so an additional switch to disconnect the antenna or an additional attenuator would probably work at short distances. Determining direction is then solely done by walking around and observe signal strength/beep vs background noise strength.

    The unit as shown weighs 1.26g including battery. A bigger battery and some modification to the circuit could increase transmitting power yes. The disk cannot be conductive, that would severely degrade antenna performance, they are made out of plastic right?Through thick brush you are good for at least 100m with this setup I`d guess, didn`t try it out though. When getting near the transmitter you might have problems determining an exact direction and your object is relatively small so that would be something to experiment with.Since you already know where the disk landed (more or less) maybe an audible signal would be better, with a little buzzer that makes a beep every 1 or 2 seconds, but what could be the range of that? Maybe about 10 to 15m? Just a thought.

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  • TomTechTod's instructable Tiny UHF Tracker Transmitter's weekly stats: 8 months ago
    • Tiny UHF Tracker Transmitter
      30,943 views
      200 favorites
      37 comments
  • TomTechTod commented on TomTechTod's instructable Tiny UHF Tracker Transmitter8 months ago
    Tiny UHF Tracker Transmitter

    Oi, sei que é difícil obter essas pecas no Brasil mas não vendo esses circuitos. Talvez alguém venda um kit um dia? (não vai ser eu :-)) As peças são baratas, não sei se a Digikey manda pra lá, o problema talvez seja taxa de importação.

    Sorry I don't have an answer to your question. You could try to lower the bias resistors of the oscillator first. Also a matched antenna output would probably greatly improve range. If you want to experiment with the circuit I suggest you go lower in frequency, for example 433MHz, makes it much easier to adjust the values. I added an image in the circuit section for a a matching circuit for 433MHz, I found these values to be more or less appropriate for the output filter. L of the oscillator would change to about 22nH.

    You are comparing apples to oranges. Yes it's backwards in time you are right, the point is to use a single miniature button cell and a PCB size of what I showed though. If anybody is willing to post an instructable for free how to built an GPS based transmitter that size I would be happy to see it. :-)Your link doesn't lead to an actual product.

    No, nothing calculated. Good comment though. Of course, when building any "intentional radiator" legislation should be observed. The circuit draws about 4mA while transmitting.

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  • TomTechTod commented on TomTechTod's instructable Tiny UHF Tracker Transmitter8 months ago
    Tiny UHF Tracker Transmitter

    Yes it would make a good instructable probably. For now you can check out my other instructable with the little FM transmitter, the whole process is shown in the video.It is really easy once you get the hang of it. All SMD components can be soldered this way but is really useful for the ones that have pads underneath like DFN packages or chips with middle ground terminals etc. Instead of a professional hotplate you can probably use a stove top. I did do it in a little toaster oven (the ones with the front door). The only thing to be careful with is the time you leave it in there. Components usually have a recommended soldering temperature profile that can be found in their datasheets. But it doesn't has to be complicated, as soon as the solder paste liquified / components are soldered o...

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    Yes it would make a good instructable probably. For now you can check out my other instructable with the little FM transmitter, the whole process is shown in the video.It is really easy once you get the hang of it. All SMD components can be soldered this way but is really useful for the ones that have pads underneath like DFN packages or chips with middle ground terminals etc. Instead of a professional hotplate you can probably use a stove top. I did do it in a little toaster oven (the ones with the front door). The only thing to be careful with is the time you leave it in there. Components usually have a recommended soldering temperature profile that can be found in their datasheets. But it doesn't has to be complicated, as soon as the solder paste liquified / components are soldered on the board remove the PCB from the hot environment. That works best of course on a hotplate or stove top because you don't have to lift the PCB and risk shifting the components while the solder is liquid.

    Schematic should be better now.

    Yes. One of the "cheap" ones. A headband magnifier would do though for 0201 packages.

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  • TomTechTod commented on TomTechTod's instructable Tiny Ladybug Sized FM Spy Bug8 months ago
    Tiny Ladybug Sized FM Spy Bug

    It's a MEMS microphone, the part number is included in the schematic

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  • TomTechTod commented on TomTechTod's instructable Tiny UHF Tracker Transmitter8 months ago
    Tiny UHF Tracker Transmitter

    Thanks. When you click on the schematic picture twice it will open in a new window then there is a link just below the picture named "original DIY file", click on it and the full res pic is available. I don`t know how to make the full res picture show in the instructable itself.

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  • TomTechTod commented on TomTechTod's instructable DC Power Harvested From Audio Jack1 year ago
    DC Power Harvested From Audio Jack

    you need to provide more details.

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  • TomTechTod commented on TomTechTod's instructable Tiny ladybug sized FM Spy Bug1 year ago
    Tiny ladybug sized FM Spy Bug

    Coming soon: 916MHz, 400m range bug in a ballpoint pen.https://www.facebook.com/Tom-Tech-1162318370524245/

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