Limpkin's blog - Electronics for a $7 USD doppler motion sensor - Comments<div>An electronics geek blog, dedicated to sharing and open source. Check out my stores: <a href="https://lectronz.com/stores/stephanelec" hreflang="en" title="Lectronz store">EU</a> / <a href="https://www.tindie.com/stores/stephanelec" hreflang="en" title="tindie store">EU & US</a>.</div>2024-03-27T19:19:38+00:00Mathieuurn:md5:51de6a3d917257edeff5a252fe925b02DotclearElectronics for a $7 USD doppler motion sensor - limpkinurn:md5:3a1d857f3d329514681367534a61f2a02017-06-27T12:41:56+02:002017-06-27T11:42:37+02:00limpkin<p>@<a href="http://www.limpkin.fr/index.php?post/2013/08/09/Making-the-electronics-for-a-%247-USD-doppler-motion-sensor#c98983" rel="ugc nofollow">Leo</a> : to be honest I have no idea if that would work...</p>Electronics for a $7 USD doppler motion sensor - Leourn:md5:81c4695a83a3269bfe235756ea3ed9822017-06-27T02:15:25+02:002017-06-27T01:15:25+02:00Leo<p>Hi, Im interested to use to measure river water and velocity level<br />
What do you think to use this?</p>Electronics for a $7 USD doppler motion sensor - limpkinurn:md5:500911ffce437da9fd83d8a610e66db02017-06-23T21:23:55+02:002017-06-23T20:24:20+02:00limpkin<p>@<a href="http://www.limpkin.fr/index.php?post/2013/08/09/Making-the-electronics-for-a-%247-USD-doppler-motion-sensor#c98504" rel="ugc nofollow">Sebastian</a> : I didn't, but I'm certain it'll work better than on humans. You should expect at least 20-30m.</p>Electronics for a $7 USD doppler motion sensor - limpkinurn:md5:3132b1be974fcdebd4ddd3482ba564202017-06-23T21:23:21+02:002017-06-23T20:23:41+02:00limpkin<p>@<a href="http://www.limpkin.fr/index.php?post/2013/08/09/Making-the-electronics-for-a-%247-USD-doppler-motion-sensor#c98633" rel="ugc nofollow">august1</a> : I'm quite sure ferrite sheets is what you're looking for :)</p>Electronics for a $7 USD doppler motion sensor - august1urn:md5:81a79d4d2f7db96598b99145e4bed66c2017-06-11T14:36:07+02:002017-06-11T13:36:07+02:00august1<p>Hello, I am currently working on a project where I use 2 HB100 (which do not work at the same time). I would like to know if it is possible to decrease the width of the azimuth radiation pattern. The desired width would be about 15 degrees.<br />
Thank you for your reply.</p>
<p>August1</p>Electronics for a $7 USD doppler motion sensor - Sebastianurn:md5:8fec0555ef8045caea3de20b8b5f65b82017-06-06T23:35:29+02:002017-06-06T22:35:29+02:00Sebastian<p>Hi limpkin, have you tried the radar for car speed measurement, for example in a parking place? And, if you have, at which distance has it detected the vehicle? Thanks!</p>Electronics for a $7 USD doppler motion sensor - limpkinurn:md5:201450d38ca52431c28b2e96e0dc2fb12017-06-05T21:58:54+02:002017-06-05T21:03:53+02:00limpkin<p>@<a href="http://www.limpkin.fr/index.php?post/2013/08/09/Making-the-electronics-for-a-%247-USD-doppler-motion-sensor#c98388" rel="ugc nofollow">Geoffrey</a> : wow... that looks like a great idea! However I'm afraid the only way to know it is to try, as there's no easy way to check how the 24GHz varies depending on the input voltage. I'm fairly certain that the cdm324 does not contain a vco.</p>Electronics for a $7 USD doppler motion sensor - Geoffreyurn:md5:c0f455307071855546ef84540724232a2017-06-03T09:48:08+02:002017-06-03T08:48:08+02:00Geoffrey<p>Hello, I have an idea for this module that I want to get your opinion on. I believe it may be possible to turn this module into an FMCW radar capable of measuring the distance to objects, similar to this (though with much less range of course): <a href="http://lea.hamradio.si/~s53mv/vnr/design.html" title="http://lea.hamradio.si/~s53mv/vnr/design.html" rel="ugc nofollow">http://lea.hamradio.si/~s53mv/vnr/d...</a></p>
<p>Even though the HB100's oscillator is not officially a VCO, it appears that the DRO in question is sensitive to input voltage and can be modulated at a rate of 3 kHz/mV: <a href="http://lea.hamradio.si/~s53mv/vnr/design.html" title="http://lea.hamradio.si/~s53mv/vnr/design.html" rel="ugc nofollow">http://lea.hamradio.si/~s53mv/vnr/d...</a><br />
Therefore, it seems it would be possible to sweep the input voltage and therefore the carrier frequency in a triangle or sawtooth pattern, and use the frequency shift of returned signals to calculate the delay/time-of-flight and therefore the distance of the objects the returns come from, instead of speed.</p>
<p>Do you see any reason why this wouldn't work?</p>
<p>Also, do you know if the CDM324 module you used in your more recent project can be modulated the same way, or if it contains a proper VCO?</p>Electronics for a $7 USD doppler motion sensor - BOBurn:md5:e8fe69f3b128f20036d0dfa7cef9dc212016-12-18T16:00:31+01:002016-12-18T16:00:31+01:00BOB<p>I've used a LM324 for this circuit and it's work...</p>
<p>-I use a potentiometer (10K) to replace fixed resistor R10 (adjust the trigger voltage of the comparator)</p>
<p>Question: R3 is used for what ?</p>Electronics for a $7 USD doppler motion sensor - limpkinurn:md5:1d3be3239fd00d910b285711a96dbb4c2016-11-25T17:57:07+01:002016-11-25T17:57:14+01:00limpkin<p>@<a href="http://www.limpkin.fr/index.php?post/2013/08/09/Making-the-electronics-for-a-%247-USD-doppler-motion-sensor#c26003" rel="ugc nofollow">Dole</a> : I'm affraid not!</p>Electronics for a $7 USD doppler motion sensor - limpkinurn:md5:3e12739033423b5c4a50f2f18128dfa42016-11-25T17:56:34+01:002016-11-25T17:56:45+01:00limpkin<p>@<a href="http://www.limpkin.fr/index.php?post/2013/08/09/Making-the-electronics-for-a-%247-USD-doppler-motion-sensor#c27006" rel="ugc nofollow">rakesh</a> : I'm affraid that is not possible due to the required impedance matching.</p>Electronics for a $7 USD doppler motion sensor - limpkinurn:md5:85fec74f4a1e173ef29dabce0d757d262016-11-25T17:55:53+01:002016-11-25T17:56:15+01:00limpkin<p>@<a href="http://www.limpkin.fr/index.php?post/2013/08/09/Making-the-electronics-for-a-%247-USD-doppler-motion-sensor#c31726" rel="ugc nofollow">Nick</a> : Hello! It draws around 50mA. I unfortunately can't tell you about the activation time, but that's what you'd need to do indeed!</p>Electronics for a $7 USD doppler motion sensor - Nickurn:md5:5bd5d78748bc44e5f54faecaeb3819922016-10-24T20:48:22+02:002016-10-24T19:48:22+02:00Nick<p>Hi Limpkin, Great work. Can you tell me who much current your board draws please? I would like to build one into a battery powered device which needs to be very low power. Also does it need any warmup time when first powered. One method for me to reduce battery consumption would be to only turn it on for a short period of time every second or two to detect if any motion is present. I have experimented with the Parallax version of this but their amplifier circuit draws 3 mA even with the Microwave turned off! Thanks</p>
<p>Nick</p>Electronics for a $7 USD doppler motion sensor - rakeshurn:md5:7271d67665eb362aad83ec1ccc60398e2016-09-21T08:58:55+02:002016-09-21T07:58:55+02:00rakesh<p>I want to make this radar for c band and to process the signals for object detection for longer range. Can i connect bigger antennas for this module?</p>Electronics for a $7 USD doppler motion sensor - Doleurn:md5:343c4cf66971cbdde4544f08737c28f72016-08-20T04:34:48+02:002016-08-20T03:34:48+02:00Dole<p>Really nice finished design. Do you think the mixer can be swapped out with a side band rejection mixer to distinguish or isolate positive or negative Doppler frequencies?</p>Electronics for a $7 USD doppler motion sensor - limpkinurn:md5:e542c83dce8e983fcbca22a220fdadc62016-06-26T16:56:37+02:002016-06-26T15:57:18+02:00limpkin<p>@<a href="http://www.limpkin.fr/index.php?post/2013/08/09/Making-the-electronics-for-a-%247-USD-doppler-motion-sensor#c22228" rel="ugc nofollow">bubble</a> : Hello there, please see the dedicated paragraph in this article... </p>Electronics for a $7 USD doppler motion sensor - bubbleurn:md5:7fd58061b924179e2e5369fc68781f562016-06-26T12:20:41+02:002016-06-26T11:20:41+02:00bubble<p>Hi limpkin,<br />
can I measure the speed of a tennis ball (while serving) with your HB-100 breakout board<br />
(and raspberry pi or arduino uno)?</p>Electronics for a $7 USD doppler motion sensor - limpkinurn:md5:084d4be9968f623183e860d7830dcfdb2016-06-17T22:45:21+02:002016-06-17T21:45:28+02:00limpkin<p>@<a href="http://www.limpkin.fr/index.php?post/2013/08/09/Making-the-electronics-for-a-%247-USD-doppler-motion-sensor#c20370" rel="ugc nofollow">Kevin</a> : you should be good ;)</p>Electronics for a $7 USD doppler motion sensor - Kevinurn:md5:d58d021daedbdb548dc3e17f69ed73562016-06-15T18:42:34+02:002016-06-15T17:42:34+02:00Kevin<p>Hi, I bought your board, and foolishly powered it briefly with reverse polarity (perhaps for a second or so). The output on a scope looks to be fine for both frequency and voltage, The pulses are still nice and square ~0-5V, and a hand-wave signal had pulse widths in the order of 10ms.</p>
<p>Do you think the board is likely to have survived?</p>Electronics for a $7 USD doppler motion sensor - limpkinurn:md5:daedf6d32462d38e35c47b81b20cf8bd2016-05-07T18:27:20+02:002016-05-07T17:27:34+02:00limpkin<p>@<a href="http://www.limpkin.fr/index.php?post/2013/08/09/Making-the-electronics-for-a-%247-USD-doppler-motion-sensor#c13957" rel="ugc nofollow">Richard</a> : Well you'll effectively reduce the maximum speed you can detect.</p>