4 ms·
The HB100 [0] and CDM324 [1] are very inexpensive little CW doppler radar modules at 10GHz and 24GHz respectively. Feed them 5v and send the mixer output to a
by jcims 7y ago
The HB100 [0] and CDM324 [1] are very inexpensive little CW doppler radar modules at 10GHz and 24GHz respectively. Feed them 5v and send the mixer output to a small microphone amp/input jack and you can record the frequency beat of most objects in motion.
[0] https://www.amazon.com/dp/B00FFW4AZ4 https://www.amazon.com/dp/B00FFW4AZ4
[1] https://www.amazon.com/dp/B07WH67J9W https://www.amazon.com/dp/B07WH67J9W
This is what it sounds like when you toss a quarter in front of an HB100. https://www.youtube.com/watch?v=8riretP8ylE https://www.youtube.com/watch?v=8riretP8ylE
The bowtie looking part is the actual flight, the other part right after that is it bouncing off the counter.
Spinning same quarter - https://www.youtube.com/watch?v=5lnYvJoxRak https://www.youtube.com/watch?v=5lnYvJoxRak
Shining it at parts of a ceiling fan - https://www.youtube.com/watch?v=tIiFvByf1CQ https://www.youtube.com/watch?v=tIiFvByf1CQ
- GhettoMaestro 7y agoIt amazes me how cheap these application-specific chips have become - it opens up so many new potentials. I can only guess that something like this would cost $1000+ roughly 10 years ago?
- blattimwind 7y agoNo, not really, doppler radar based proximity sensors (used in e.g. baths) cost about 40 € more than 10 years ago. It's not complicated technology.
- scoot 7y agoWhat's an e.g. bath?
- deleted 7y ago[deleted]
- gregoryl 7y agoe.g. is https://en.wiktionary.org/wiki/exempli_gratia https://en.wiktionary.org/wiki/exempli_gratia which you can pretty much read as "for example, [example(s)]"
- jcims 7y agoMy mnemonic is ‘eggs ample’. :) Commonly confused with i.e. (id est), which trasnslates to ‘that is’. The mnemonic there for me is ‘in other words’.
- scoot 7y agoSorry, I should have guessed my comment would be lost on those who don't know how to use "e.g." correctly.
- gregoryl 7y agoJust assuming you were being earnest (perhaps learning english!) as there wasn't much to gain from interpreting it another way.
- mcguire 7y agoI don't know what they're doing in a bath, but small radar systems have been used as proximity fuses for anti-aircraft shells since WWII.
- blattimwind 7y agoAs light switches and such; PIR sensors don't really work in a shower room, for example.
- jcims 7y agoThere actually isn’t much to these tbh, oscillator, mixer and pcb antennas. To use these in an application you would have to still process the analog waveform coming out. Fortunately the frequency is very low (audio range) allowing for all manner of inexpensive detection/measurement circuits.
- tyingq 7y agoI'm sure they are cheaper, but I don't think they were ever really expensive. They have been used for automatic doors, like at the grocery store, for quite some time.
- jcims 7y agoNice teardown https://www.allaboutcircuits.com/news/teardown-tuesday-hb100-doppler-radar-module/ https://www.allaboutcircuits.com/news/teardown-tuesday-hb100...