These little devils are movement detectors, bought from Ali Express on a whim and they use the PCB as the antenna (3Ghz) – hence the ridiculously low price. So just a quick one – I ordered 2 and they arrived the other day – I’ve hooked them up to 5v (they work from 3v3 to 20vDC) and use less than 3ma. 3 pin connector gives a positive output on movement – and the output stays high for around 30 seconds.
Updated April 2017 - see also https://tech.scargill.net/microwave-for-the-weekend/
On the back there is a pair of connection points (soldering iron needed) and if you put a 10k resistor across them (I found this out by trial and error as there is very little info on these units – at least in English) the pulse goes down to around a second. VERY sensitive and although I’ve only done the briefest of tests I can confirm they can detect hand movement through 0.5” of chipboard !!
According to the blurb they pick up movement 360 degrees and have a detection of 6-9 metres. Applications include security, intelligent lighting, toys etc.
What I DID find when testing this and a later model (see above) is sensitivity to power supply - it is probably no good sticking it on the same supply as an ESP8266, the noise spikes will make the board unreliable. My solution is a 10r resistor in series with the 5v supply - and a 330u 6v cap (from the microwave board end of that resistor) - to ground - works a TREAT.
Both sensors work well, let's have your thoughts (no theories about getting cancer from radiation please).