#135 Radar Sensors / Switches: Comparison and Tests

#135 Radar Sensors / Switches: Comparison and Tests

In video #40, I compared ultrasonic distance
sensors, and in video #97 I compared PIR sensors.
Both can be used to detect movement, and both
use different physical principles.
Today we will have a look at a new kid
This is one of the strangest devices which
came across my desk.
Small and some of them, dirt cheap.
So, let’s explore, if they are also useful.
The invention of radar influenced the way
world war two went, because it was possible
to detect planes of the enemy and shoot them
And since then, this technology made civil
aviation as we know it possible, because it
can detect movement of metallic surfaces over
Of course, the technology can also be used
against us, for example if we are trapped
while speeding…
Till a few month ago, radar devices were quite
big and quite expensive.
This is, because they work on high frequencies,
and need a strong sender and a big antenna.
This antenna sends a signal, usually only
in one direction.
In parallel, a receiver listens on the same
If the signal hits a metallic surface, it
is reflected back to the receiver.
And if the surface moves, the reflected frequency
is slightly different than the one sent out.
This difference is proportional to the speed
of the surface and the effect is called “doppler
We all know this effect from police cars which
pass by and sound different if they move towards
or away from us.
So, the parts we need to build a radar are:
An antenna
A sender
A receiver
A Mixer to bring the signal to low frequency
And a system for analysis
And now came these small devices which are
sold as “radar sensing devices”.
They come in different shapes, but all look
somehow similar: They consist of an IC, a
transistor, some passive elements, and a “snake”
like trace on the PCB.
There are some investigations in how these
devices work, but for me, this is still not
completely clear.
What is obvious is, that the sender, the receiver,
and the mixer all are integrated in one simple
The antenna must be the trails on the PCB.
This is, what we can call: “Reduce to the
The IC is only low frequency and is used for
It has nothing to do with the radar, and it
is a very similar chip as used in the PIR
Its main responsibility is to create the timing
of the digital signal.
I leave a link in the description for more
information about the working principle of
these devices.
But I have to admit, I still did not find
a convincing explanation on how we can build
a sender, a receiver, and a mixer into one
If this works, it is really intelligent engineering!
Just a small remark about metal: Radar can
not only detect metal.
It also can detect water.
This is used for example to create the rain
maps on your smartphones.
And humans consist mainly of water…
So, I bought a few of these devices available
on the internet.
And now, I want to answer some questions:
– Can we use them on 3.3 or 5 volts?
– How much current they draw?
– How long do they stay “ON” if they detected
– How big is the distance they can detect
the movement of an adult human?
– What is the angle of detection?
– Do they “see” trough obstacles like
glass, wood, or even walls?
– What additional features do they offer?
– Can I use more than one device in the same
Or are there interferences?
And because they work on quite high frequencies,
I want also to know if they disturb my Wi-Fi
First, we look at the contenders:
The RCWL-0516 is the cheapest device and it
should work from 3.3 to 28 volts.
It offers a connection for a LDR resistor
to inhibit its function if the ambient light
level is already high.
I did not test this function.
It also has a stabilized output of 3.3 volts
and you influence its sensitivity and delay
time by adding a resistor or a capacitor.
A small remark: The 3.3 volt pin is an output.
The Vcc pin is called Vin.
The next is the HW-MS03.
It looks similar, and also has a similar size,
but you cannot influence its behavior by adding
You would have to replace them.
Next comes the XYC-WB-G1.
It also has no possibilities to add components,
and it has a JST 2.0 connector.
The WB3-12 seems to be built for a particular
purpose: To be used in round lamps.
To get this small footprint, they used two
PCBs which are soldered together.
It also seems to have the possibility to add
an LDR.
The sensitivity and the delay can be influenced
by replacing two resistors.
They are quite tiny, but accessible.
This device also needs a pull-up resistor
at the output.
Otherwise it will not work.
The last in the crowd is the HFS-DC06.
This device is bigger than the others.
It has trim potentiometers to influence delay
and sensitivity.
And it has some sort of metal shielding.
It is also the most expensive of all.
First, we tested the possible supply voltages.
Despite the promises in the leaflets, most
of the devices are not usable at 3.3 volt.
They expose a particular behavior: If no movement
is detected, the output switch forth and back
between ON and OFF.
The only module which works also on 3.3V is
the HFS-DC06.
All modules claim to run up to 12 volts or
I did not test it, but because most of them
have some sort of voltage regulators on board,
and all only draw small currents, I can believe,
that they work also on higher voltages.
Next, we measured the current needed during
Most of them only need 2-3 mA.
Only the HFS-DC06 needs 14 to 22 mA.
A quick comparison with PIR sensors shows,
that these consume below 1 mA, and the ultrasonic
sensors consume around 5 mA.
The time a sensor stays “ON” after triggering
decides in which scenario we can use it.
If we work with microcontrollers, we prefer
a short on-time, because we want to define
the timing with our software.
If we want to use the sensor stand-alone,
we usually need a longer on-time.
Without changing or adding any parts on the
sensors, two sensors stay on for about 5 seconds,
and the other two stay on for 20 to 30 seconds.
Again, the HFS-DC06 is different: It starts
at 5 seconds and can be much longer, depending
on the position of the trim potentiometer.
We were not patient enough to test the longest
possible delay.
Now comes the fun: How well do these devices
detect movements of humans?
For these tests, I had help from a neighbor.
Because my house is quite small, and the weather
outside is rainy, we decided to use a 4-meter
Anyway, in many situations, 4 meters is already
too much.
All devices were able to detect even small
movements of arms over a distance of 4 meters.
Which is for me very astonishing, that such
simple devices have this capability.
The only device which was clearly more sensitive
was again the HFS-DC06.
We did a short test, and were able to detect
also movements over a distance of 8 meters.
Of course, with the maximum sensitivity selected.
BTW: Its sensitivity selection works fine
and you can restrict the detection range down
to about 1 meter.
PIR and ultrasonic detectors had a detection
range of about +/- 30 degrees.
How about these new devices?
Radars, in general are very direction sensitive,
because we want to detect also exactly, where
the planes are.
In order to test this, we turned the sensors
by 180 degrees and did the same tests again.
Interestingly, we did not see a difference
in sensitivity.
With the exception of the HFS-DC06.
This device was not sensitive at all in the
reverse direction.
So, we turned the sensors only 90 degrees.
And, strange enough, they worked as good as
The only exception, again, was the HFS-DC06.
It only has an opening of about 180 degrees.
The other devices are sensitive over 360 degrees.
And, as we will see later, also up and down.
So, they expose no directivity at all.
Very interesting!
We all know, that radio waves also travel
through walls.
And because our radar sensors claim to work
with radio waves, we have to test also this
So, the first test is if they travel through
a glass window.
We discovered, that glass is quite a strong
Also on shorter distances, we were not able
to detect movements behind glass.
Next, we tried the wooden table.
For this experiment, I had to take the role
of an “underdog” and go on my knees.
Here, the devices had no problem to detect
even very small movements.
And the wood has a thickness of about 4 cm
or 1.6 inches.
5 mm or 0.2-inch Acrylic glass did also not
hinder the sensitivity a lot.
15mm or 0.6-inch wood however, reduced the
sensitivity about 25%.
So, all-in all this is a great new category
of devices.
Some of them claim to work on 5.8 GHz, others
on 24 GHz.
But the dimensions are not much different.
So, these numbers are hard to believe for
And I read somewhere, that they can work also
on 2.4 GHz (which would only be a missing
point in the 24 GHz number).
And this would be very harmful for my Wi-Fi
or Bluetooth devices.
So, let’s check.
My spectrum analyzer only covers up to 3 GHz.
So, I cannot measure the 5.8 GHz Wi-Fi band.
But at least, below 3 GHz none of the devices
emitted energy.
Except the XYC-WB-G1: It emits a small signal
around 3 GHz.
I did not found any information about this
device, and even the picture on Aliexpress
is different to the one I got.
But still, the signal is not on 2.4 and quite
So, no danger here.
The next question, of course: What happens,
if I use more than one device in the same
To test that, we powered all available devices
on the table and did the sensitivity test.
We did not discover any difference.
So, they seem to somehow have no big influence
on each other.
Which, again, is a mystery for me.
Even two of the very same make worked without
any problems in a distance of 10 cm!
– These cheap and small sensors all work
– They can detect human movements in a distance
of at last 4 meters
– Most of them work from 5 volts and up.
Only one worked on 3.3 volts
– Sensitivity and delay time can be influenced
by either trim potentiometers, added resistors
or capacitors, or by replacing resistors or
The latter is not easy because the parts are
very small.
– For the usage with microcontrollers, 5 second
delay is the maximum.
20-30 seconds is useless.
– The devices work in all directions.
Only one exception has a directionality
– These devices detect movement also through
plastic, or wood.
Even thin walls are no big obstacle.
All-in all my favorite is the RCWL-0516.
It is simple and cheap, has a decent sensitivity
and a short delay time.
The only disadvantage: It cannot be used in
3.3 volt environments.
If you need a lot of flexibility, the HFS-DC06
is the best choice.
However, it is roughly 10 times more expensive.
The others are somehow in-between.
I like these devices, also because they can
be mounted inside a plastic box without any
contact to the outside.
An example for that is this 220-volt proximity
sensor form Banggood.
It is a completely closed plastic case, and
it comes with dip switches to select sensitivity
and delay.
I mounted one of those for my remote desk
in my lab.
And it works very well.
I hope, this video was useful or at least
interesting for you.
If true, then like.

100 Replies to “#135 Radar Sensors / Switches: Comparison and Tests”

  1. Excellent video. I recently bought a large assortment of these modules on Ebay and tested them. All of your findings and conclusions are correct. Thanks for taking the time to make this video.

  2. Actually HFS-DC06 also have other different input voltage level, DC5v 8-15v 12-30V, and the delay time is 2-120s adjustable, Sensing Distance more than 12m, Sensing Angle is right Ahead Cone 360 degree

  3. Andreas thank you for your videos. Did you go further investigating false triggers due proximity with ESP8266? (like in https://github.com/jdesbonnet/RCWL-0516/issues/2?_pjax=%23js-repo-pjax-container ?) thanks !

  4. Great video. I was hoping they would be more directional to replace my PIR sensors (I need them to distinguish between movement in my corridor vs inside a room), and now I'm considering creating barriers using glass.

  5. Hi Andreas,
    I only comment now (quite a while after watching this for the first time).
    I got myself 10 RCWL-0516 sensors and I just LOVE them. I automated my lights in both my house and workshop. I even made an alarm sensor unit to monitor movement at my main gate. Thanks to this unit I was able to catch two thieves in the act of trying to break in (South Africa has very high crime rate, so you need to do anything possible to give you an early warning)
    I did however found that if you are running the RCWL-0516 over a long distance you need to add a PI filter. Two big sized capacitors (100-470uF) with a 10ohm resistor in series (two caps ground tied to ground, one cap receives the supply power, resistor in series to the next cap positive and that goes to VIn of the RCWL. That completely eliminated any false alarms.
    The unit is very sensitive.It picks up small animals such as pigeons and cats. Oh, and watch out for FOG. Moving moisture seriously affects the unit. That was the only time it failed (false alarms). So for people living in high fog areas, sorry, this will not work.
    Thanks for a great channel. Love your work. Keep it up.

  6. Question: These chips have a transmitter and receiver antenna and the transmitter is constantly transmitting. How does the receiver avoid getting blown out by the TX antenna that is transmitting on the exact same frequency it is listening for? Yes I know some of the incoming frequency is sometimes Doppler shifted but much of the time it isn't. So it's not like you can just filter out the TX frequency. Or perhaps that's exactly what it's doing and just looking for what's left which is the Doppler shifted changes?

  7. Two points are still unclear for me: 1) Could I measure indirectly, somehow, the distance to the object?
    2) Detection angle is 360 Deg for most of them and 180deg for one. I cannot therefore have a smaller detecting cone in front of the sensor of, like for parking sensors, is that right? Many thanks, very informative

  8. There's a reversing sensor for cars that appears to work in the same way, but it detects anything moving towards it. If you do an eBay search for "electromagnetic parking sensor" you'll find one.
    They state that you can hide it behind the bumper, but I'm thinking of putting one on the outside and covering with high visibility reflective tape!

  9. Датчик движения RCWL-0516
    Время задержки включения будет:
    T = 245 x CTM, Где CTM – в МкФ, T – в секундах

  10. Very good video, just a question: did you try to make an antenna to have a thinner angle? It should work isn’t it?

  11. Interesting. Are there any sensors like this, that output at higher frequencies, are capable of detecting small (say ~12"/30cm) objects, out to say 200-250 meters?
    What i'd really like a small cone radar I can scan a small patch of sky. It'd be even more beneficial If it could have some sort of interrogation/reply included.
    I really want to develop a few radar/IR target ID and IFF interrogation systems. It'd be cool to have IR cameras with ranging and signaling, along with radar information.

  12. Which one is safe to use for motion detection in home environment. PIR or Microwave or Dual Technology (PIR + Ultrasonic sonar sensor)

  13. Can you measure distance in arduino? I have a project where I need such a sensor but within distance range only let's say 1.5 meters only

  14. Very informative video Andreas! Thank you. I'm brand new to IOT and so thank you for suffering through my newbie question. Are these devices just binary in their response (ON if someone is in the field, OFF if no one is there), or can they also report distance, in the same way a HC-SR04 ultrasonic sensor does? trying to get a dimming effect on an LED based on proximity. Thank you!

  15. I am interested in monitoring heart rate and breathing rate (sleep apnea) and watched this video using radar.
    https://youtu.be/0kEdCUdWDdw. Can you use one of your radar sensors for this? I like your GREAT video here.

  16. I saw parking sensor radars on ebay and they are cheap. they are used to avoid collisions. I am not sure how these radars compare to radar sensor in this video, maybe it would be worth testing. I could probably use them on my drones to avoid collisions. I have been curious for a while about radar, I guess it's time to buy some radar sensors. thanks for sharing this video, it was inspirational.

  17. I made a small project with the RCWL-0516 and all worked fine…until I put it in a plastic box along with a Rpi Zero W. The Pi reads the data from the radar on GPIO 17. I dont understand why the plastic box is blocking the radar, any idea? Did you try enclosing the RCWL–516 in a box for your test? Many thanks in advance for your tips.

  18. but in the first you told that they used to detect planes which are made from metals so what if we want to detect only metals which sensors are best for that ?

  19. And so they can people with special spirit all so a frecuenty lower and people the intelligence. how they do this of ith radars they use then to put the ideas to a other person or they have a connection or to spy

  20. I love you sir for doing this amazing job, i am planning to build a security company where we preferred to use RCWL-0516 it was an amazing device but with out your amazing work here in this video we could not have gone far it helped me so much.

  21. Great video. Appreciate the effort to examine and compare the most important characteristics of each unit with a scientific approach. I agree with you, even if the units are simply measuring the variance in transmitter output to determine motion, some sort of return circuit is required. Thanks again.

  22. Love your stuff. This amplifier circuit might come in handy if you do more videos. https://www.youtube.com/watch?v=snGy9pxeQj4

  23. Very nicely done – appreciate your thoroughness on the testing; gave me some background on what they might do.

  24. Hi. I've recently discovered the RCWL-0516 and in search of more specifics I've then found your video.Your extensive tests are very helpful. Especially the needed voltage to run it, the diagnosis if the devices interfere with each other, the directionality and what they penetrate.

    Viele Grüsse aus dem Hackerspace Ruum42 aus der Ostschweiz.

  25. Muy bueno el video. gracias . Me sirve mucho para mis pretenciones. (Very good video. Thank you . It helps me a lot for my pretensions )

  26. thanks for your detailed summary – my favourite is also the RCWL-0516 (I've got a lot of them for experimental purposes) and I've also got some WB3-12 sensors but in contrast to yours, mine has got a delay-time of just 1sec – well, strange. I tried to find a way to influence this delay but so far I didn't find a way to manage it. Apart from this there is another thing to mention: in contrast to your words I just experienced, that WB3-12 (the white round) and the RCWL-xxxx do interfere each other (however, I've tried it with just 30cm distance) – none of them is triggering in this close setting but actually it doesn't matter ..just saying – thanks and Grüße aus A in die CH .)

  27. i tried 9196 it works as you mentioned but at 180 degree rotation the range and sensitivity drops very much. the chip side facing us works good. i tested it behind a metal gate half of the height covered with metal sheet and half of it with striped bars. the circuit dint work even though there is enough gap for the waves to go.

  28. Hallo Andreas, funktioniert der RCWL-0516 auch hinter einer 3 bis 5 mm starken Edelstahlplatte ??? Könntest du das bitte testen ? und was ich fragen wollte die Entfernung lässt sich auf 1 Meter runter reduzieren oder ?

  29. A new one to try if you have $310 US burning a hole in your pocket. A millimeter wave transceiver: https://www.digikey.com/en/product-highlight/t/texas-instruments/iwr1443-single-chip-mmwave-sensor?utm_medium=email&utm_source=npa&utm_campaign=44597_NPA1902A&utm_content=mainproductlearnmore_US_296-Texas_Instruments&utm_cid=10958823&mkt_tok=eyJpIjoiWkdRNVl6ZGxOakV3WWprNSIsInQiOiJKZTR1MmN0XC9KTngxT3psRlBPMldnUnUrbThzWlkrWFdYS2ZSbitTV2JwbG5kanU5VDg5eVNDelVRVGtFaUFGZ1NSYjRnY2o5UzBjS29Gb0pXZ08yVHZlU1hXaDJsUkV5eVprY0RabkZtbHNiYjlqbG0rRVdSRFJvbHVZNEJueE8ifQ%3D%3D

  30. hiii can i detect moisture(water level) in fresh concrete /// please look this link

    please see last 3 point
    please help me

  31. Nice introduction in Mircorwaves. I like your channel very much.Also becaues you are a swiss guy too 🙂 It's very nice to see, that we have such brillant heads in our small country 😉 Since 3 days I played around with the RCWL-0516 and I'm very happy with it. Stay healthy and I hope a lot more videos are coming up 🙂 Next I want to build a LoRa Gateway because in my region no one have it. A liebe Gruess und sunnigs Wätter 🙂

  32. Excellent work. Have you been able to find a device that can use radar to detect just presence, not requiring motion? My Use Case is presence detection of a senior in a room when they are passive. I was hoping the Bosch Radion TriTech which includes radar would do this but it only looks for motion. Frank

  33. Hallo und danke für die tollen Videos. Ich habe den hfs-dc06 und musste lange fummeln weil er nicht funktioniert hat. In deiner Beschreibung steht dass er sowohl mit 3,3V als auch mit 5V als Spannungsversorgung betrieben werden kann. Ich habe bei 5V irgendwann gesehen dass die kleine LED leicht glimmte. Da der Sensor auch mit 12V angegeben ist habe ich es damit versucht. Ab ca. 7V arbeitet er dann gut. Mit 12V problemlos. Gibt es da unterschiedliche Modelle? 2. Kann man die Zeit auch kleiner bekommen. Mit dem. Poti bin ich bei ca. 3Sekunden und komme nicht weiter runter. Kann man den Poti auslöten und einen Kleineren einbauen?


  34. I am being gangstalked. The criminals have made my house into a gas chamber, exposing me and my child to low level toxic gasses 24/7. I believe they are managing to do this by putting sensors all over the house and installing a network of fine gas pipes between the walls of the house, which are connected to the gas cylinders in the adjoining house. The gases can be ramped up in real time as I, for example, move from room to room, open the windows and even if I open my eyes after sleeping!
    I believe the gases are being controlled remotely, partly by artificial intelligence, partly by human intervention. Andreas, please can you tell me what device to use to locate the toxic gas piping and the sensors. This is my theory of how they are poisoning me and my child in my home. If you can think of other ways they may be pushing these gases into a U.K. home, I would value your and your subscribers advice. NB: one minute one gas is emitted from a particular area. Another minute, a different gas is emitted from same area. So I imagine it’s quite a sophisticated system the criminals have set up. Thanking you kindly for an urgent reply.

  35. Hi Andreas, I would like to use HFS-DC06 behind a mirror in order to detect movement. As you know, mirror is plated, so my doubt is weather it will work or not and if I can decrease sensitivity for a range of 1-2 meters. Thanks

  36. the HFS-DC06 probably has a higher gain directional antenna. It almost perfectly fits the bill: Half the detection area for double the power/range.

  37. There is no receiver and/or mixer… The transistor (and the capacitors and antenna as an inductor) generate the RF signal. When the signal is distorted by moving objects causing a doppler shift for example, the reflected signal interferes with the sent signal this increases or decreases the load on the generated RF signal. Since you are not trying to detect movement and not trying to measure the speed of the movement. The frequency difference isn't really relevant, so you can essentially just add some filtering circuitry and measure the amplitude of the generated RF signal and detect sudden changes in amplitude.
    Check out this video for more details. He does a pretty good job at analyzing the circuitry. https://youtu.be/Hf19hc9PtcE?t=245

  38. Actually this is a very old technology.
    In the early days of electronics, vacuum tubes / valves were Very expensive. So the valves were used to perform multiple functions. A radio receiver consisted of a one-valve oscillator. RF signals were received by an antenna and then passed through a tuned circuit. The filtered RF signal was applied to the oscillator, where the signal was mixed with the oscillator's RF signal (homodyne detection). The result was a low-frequency audio signal, which the user could hear. The same process is happening in this circuit.

    The RCWL-0516 is a grounded-collector oscillator. The transistor's collector is connected to a constant voltage V+ source, which is at AC ground. The transistor's emitter is connected to a 1/4 wavelength transmission line (the S-shaped PCB trace), one end of which is connected to the emitter (the signal source) and the other end of which is connected (via capacitors) to ground. The transistor's base is connected to the junction of the bias resistors. Oscillation occurs because feedback / coupling occurs between the base and the emitter: there is a PCB-trace stub connected to the base, which is positioned near enough to the trace through which the emitter's signal flows so that some of the transistor's output signal is fedback to the base.
    The S-shaped PBC trace acts not only as a resonant transmission line, but also as an antenna, which both transmits and receives. An operating frequency of 24 GHz corresponds to a wavelength in free space of 1.25 cm, so a 1/4 wavelength antenna ("meander microstripline monopole antenna") would be about about 3 mm long.

  39. I don't think speed radars use doppler effect. for such high frequencies you need much higher speed to observe doppler effect. What's used is a bit different – same that's used in light distance measurements (not sure how it's called)

  40. Hi, great video! Did you make any experiemnts blocking or directing these signals? I've made tests with grounded aluminium foil blocking a RCWL0516 with no success.

  41. It is UWB Radar technology.Sub nsec pulses (million of them every period of transmission) https://www.youtube.com/watch?v=Grfx3Q2Mgro

  42. I have a few radar modules which I got from aliexpress, they are different from yours but they work. Unfortunately they are not suitable for my purpose because I need something that not only detects motion, but estimates the speed of the motion also. Thus instead of a binary on/off output I would need either an analog out, ADC out, PWM modulated out or something similar. I'm not aware of anything like this available, at least not from the usual sources and in my price range. 🙁

  43. I want something that detects movement inside my room but not outside the room. Is there a way to reduce sensitivity "inside the walls"?

  44. Thanks for this video! 🙂
    I want to use such device to build a sensor for my bike (3 wheel velomobile, https://youtu.be/8prtmzIpK0Y ). The pupuse is to get warned if an object is approaching from behind. I am worried about if this still works if I am moving with it and maybe I will get to many false positives because of obstacles on the road.
    The second idea is a alarm function of somebody is moving over the vehicle and touching it (this happens very often). I this case the omnidirectional sensivity is not what I need because it would be too sensitive and triggers an alarm if people just walking around. The question is, if I would be able to get an influence on the directional behavior be putting the moduls in a metallic shell which is just open to one direction? Or would it be then destroyed?

  45. After 2 years this is still an excellent video.

    Good to know that the radar sensors don't harm your WiFi. As I can confirm, since you can mount the sensor behind a piece of wood, the sensor also does not harm your wife's eye and this makes such a sensor perfect for home automation systems 😁

  46. Hello Mr Spiess, that noise at 1800Mhz that you labeled is a GSM band used by the telecommunications industry, it’s known as DCS-1800 or B3 LTE

  47. Great Video! Can i use this Sensors to build a blind spot detector on my car? The Radar sensor must the metal of a car detected during the drive. Wich Sensor is for this Project the best? Any idea?

  48. Hi! Thank you for the video! I've been working with Vl53l1x but It has real problems with precision, %3. Do you know a similar sensor with a high precision and resolution? By the way, I need it for 2,5 meters. Thank

  49. They mostly seem to be described as microwave sensors, you can detect objects moving sideways, so it's not Doppler!?, they seem very similar to the head of tank proximity round. An example of how they may work is a ham radio antenna, if you put your hand near the antenna the SWR changes.

  50. You did not answer a crucial question, HOW LONG DOES IT TAKE TO DETECT MOTION, a PIR takes 3-5 seconds, but with some hardware modification like removal of resistors and bridging, the DETECTION DELAY becomes 0.3 seconds. There are many applications where the alarm needs to be nearly instant, I am really struggling to understand why they retard these sensors to be so slow, so please answer my question, and if its above 0.5 seconds — how to modify it to make it faster, the sensor in question: RCWL-0516

Leave a Reply

Your email address will not be published. Required fields are marked *