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RCWL-0516 Microwave Proximity Sensor - With & Without Arduino

DroneBot Workshop
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The RCWL-0516 is an inexpensive proximity sensor that works using microwaves and Doppler Radar. It can be used on its own or with an Arduino, I will show you both ways.

Article and code downloads at https://dbot.ws/rcwl0516

Today we will look at another proximity sensor, the RCWL-0516. This device works using microwaves and the Doppler Effect to detect the presence of humans (and other creatures) in a room. It is inexpensive and can be used by itself or in conjunction with an Arduino.

Don’t be concerned about the microwave aspect, this device emits a very low level of microwave radiation at 3.18 GHz, which is on the low-end of the microwave spectrum. It is perfectly safe to experiment with and to use in your projects.

The device is very inexpensive and can be obtained on eBay, Amazon, and probably at your local electronics shop (which is where I got mine) for around 2-3 US dollars.

The RCWL-0516 operates using the “Doppler Effect”, a phenomenon discovered in 1842 by Austrian physicist Christian Doppler. The Doppler Effect describes a change in frequency observed by a stationary observer when the source of the frequency is moving.

If you have ever heard the sound of a train as it races towards and then away from you, or an ambulance as it races down the road, you will have heard the siren frequency changing as the object approaches, passes, and moves away from you. That is the Doppler Effect in action.

In the RCWL-0515 microwaves are sent out and reflected back. Any moving object in the area will change the frequency of the reflected waves, thus triggering the device.

I will show you how to use the RCWL-0516 on its own, both by itself and with an optional light sensor. You'll see that because it uses microwaves it is still operational even when encased in a plastic enclosure.

Then we will use an Arduino with the RCWL-0516. I’ll show you how to make the device “latch”, great for an intruder alarm or automatic light switch. Then I will show you how I built a remote sensor using an RCWL-0516 and two Arduino's.

Here is the Table of Contents for today's video:

00:00 - Introduction
03:12 - The RCWL-0516 & Doppler Effect
09:33 - Basic Hookup & Demo
12:35 - Light Sensor Hookup & Demo
15:14 - Arduino Latching Device Hookup & Code
20:31 - Arduino Latching Device Demo
23:44 - Arduino Remote - Transmitter Hookup & Code
29:02 - Arduino Remote - Receiver Hookup & Code
32:19 - Arduino Remote Demo

As always there is an article with more details and all the Arduino code, you will find it at https://dbot.ws/rcwl0516.

"Never trust a computer you can’t throw out a window." — Steve Wozniak

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Don’t be concerned about the microwave aspect, this device emits a very low level of microwave radiation at 3.18 GHz, which is on the low-end of the microwave spectrum. It is perfectly safe to experiment with and to use in your projects.

After watching the workshop I bought 10 of these. 

Now this might be a bit controversial, but I still have some reservations regarding the "Don’t be concerned about the microwave aspect".

I am not deep into electronics to come on my own to a qualified opinion regarding the health aspect of this low-end of the microwave spectrum and very low power radiation.

In that respect I would like to get some more qualified opinion. Could I use these devices inside my home always active (lets say to control light or as a burglar alarm etc.) and not be concerned at all by their radiation.

I understand that the Chinese release all these dirt cheap kind of experimental chips. But I doubt that they would care about any health questions.

Thus before I decide where and how to use these devices I would much appreciate to get some opinions on above.

Another small question I have concerning these devices:

I understand that they radiate, sensor in all directions (360°)while they are more sensitive where they should according to specs.

How can one safely limit the device radius? I read that aluminium does block the microwaves but that it should be 1cm from the device away. Does anybody have experience with this?



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If you're terribly concerned about the radiation, then just make a small, thimble shaped aluminum foil (double thickness) hollowed out to about 2-3 cm deep and stick the device in the bottom with the wires exiting behind.

You can then put one on each side of the door of interest and the cone will limit the area of exposure to directly below the sensor. By having one on either side of the door, you can tell (from which one triggers first and which follows) whether the person is entering or leaving the room. You can then adjust the lights accordingly.

Of course, if you have multiple people entering and leaving and want the lights on when the first enters and off when the last leaves, then your logic will be more complicated.

Anyway, the zone of potential danger is now reduced to two small areas on either side of the doorway, so unless you tend to spend a lot of time lounging in doorways, you're pretty safe.

In the case of burglars, they'd be relatively hazard free as well - unless they're unskilled enough to have to lounge in the doorway long enough to pick the lock or kick repeatedly at the door.

activ8me liked
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Thank you for the suggestion.

Good advice. I will try that. 

No, I am not terribly concerned about the radiation, I just feel better being safe than sorry. Then it is not only about me or a prototype, but also in respect to implementing this kind of tech in a commercial product. I believe such effects just in general should be taken more seriously and manufacturers should be more serious about those.

With radiation, wireless, G4/5, whatever, in my experience some people react very sensitive to it, others not. And if any secondary effects exist, they might never get identified or only decades later.

I guess that is why in my first post I have called this a kind of controversial subject. Of course, I am surrounded by radiation of multiple kinds and happily using all this over the air technology. So I am by no means just against it. I just believe it should be taken into account.