The text says that the low pass filter is set by R3 and C9. I think from the circuit diagram above the text, this should be R8 and C9. Actually R8 in parallel with R7 but since R7>>R8 it's near enough.

Thank you so much for writing this guide. Really useful.

Pretty sure "velocity is much less than light speed" was intended-- v<<c

Hello everyone,

Does anyone know if maybe modifying the voltage or resistance at some point could potentially adapt the range of the sensor? i made a light with the sensor but it turns on way too much.

Thanks!

I've been through the notes and as far as I can see, this question hasn't been covered. The "on" time where the output pin is held high is around 2 seconds, I see from other notes that this can be increased by putting a capacitor across C-TM, but I want to significantly DECREASE the time the output is held high and trigger time. I've tried various resistors across C-TM and can increase the time, but have had no luck in decreasing the time. Perhaps explaining what I am hoping to achieve would help. I'm trying to create a pulse count circuit where, the system will only trigger after two or three pulses within 2 seconds (similar to alarm PIR detectors) to reduce false alarms. Has anyone been able to decrease the trigger time?

I was wondering if there were a way to modify this to give a variable or PWM output representing a distance, or speed?

I figure a number of these placed strategically might allow one to map and object in 3d space.

The actual bias voltage is the ratio of the ground resistor divided by the sum of the two resistors times the voltage.

Rg / (Rv + Rg) * Vin = 2200 / (2200 + 4700) * 3.3 = 1.052 volts

I hope it doesn't happen to you, but I just hot-washed an RCWL-0516 in my shirt pocket at 40°C in a washing machine, followed by an "extra dry" tumble. It still works.

I am designing my own board with microcontroller (either ESP32 or ATmega), i would like to include the doppler sensor design directly to that board. I am bit tight on space and i was thinking that maybe i can just use the RF part of this circuit and replace RCWL 9196 block with my own circuitry to detect the output frequency shift myself. Effectively i want to cut the RCWL-0516 part in half and throw the IC half away.

I guess we can detect the baseband (downconverted doppler shift signal) using ADC of microcontroller. Maybe with little help of LM358 opamp or something... Another good thing about this might be that we would be able to fine tune signal processing in firmware in order to achieve desired sensitivity and range, without modifying analog circuitry, timing capacitors, etc...

Any ideas how to do this? Unfortunately i don't have scope at hand :/

I've mounted the RCWL-0516 on a small, solderless breadboard with a battery so it can be easily placed in different locations. It seems that the sensor's performance, that is, the trigger sensitivity, varies noticeably depending on the size of the room and where the unit is placed in the room.

Is this behavior to be expected? Since the unit works by interpreting reflected waves, it would make sense that where it is placed could affect its performance. Nearby objects might affect the quality of the reflected waves and whether the RCWL-0516 interprets them as movement.

I cut loose pin1 from PCB, powered up the module (worked unchanged!) and probed pin1:
1.4mV against GND - so definitely no output.
However it has changed mode to "not retriggerable" . in line with the "old" pin function, so pin1 description on https://github.com/jdesbonnet/RCWL-0516 could use an update

/jOERG

I'm searching for the oscillator which make 3.1 GHz.
I would like to decrease the frequency down to 2.5 GHz.
Do you know, where is the R/C-part in the schematic?
Edit:
Now i see, it's a colpitt oscillator. The frequency change is probably not possible (?)

Hello folks,

with my newest order I received six rcwl-0516 with a sightly different layout.

Most significant is the back with this new chip labeled '7133-1' which looks to be a

HT7133-1 30mA Low Power LDO The HT71XX-1 series is a set of three-terminal low power high voltage regulators implemented in CMOS technology.
Source: https://www.digchip.com/datasheets/parts/datasheet/196/HT7133-1.php

Also the logos missing from the board itself as well on the rcwl-9196 microchip.

Some speculations what the added low power ldo could be good for?

I used this sensor with a esp8266 and i have a lot of false triggers. Seems to be strongly affect by the wireless network , in general , by strong electromagnetic fields . I tried to place him at a considerable distance from esp8266 and I used a lot of decoupling capacitors. Sure that the false switching operations were far fewer .
I would like to know if anyone met this problem and how to solve it .
If I mount a metalic shield on the back of the sensor, may this affect its detection properties ? Thanks .

I've read many articles about this thing being tooo sensitive.
I've rigged it with an esp8266 chip, from my observation, if way less sensitive the I expected it to be.
Is it normal for this board to not react to small movements such as turning of the head or raising of the arm from an arms length distance?
I was actually looking for a device that would react to such movements.

I have tested pulling LOW on CDS module won't trigger the motion, but I just know whether the module is fully disabled or just triggering part. I kept the module close to my desktop and so I am worried about sitting close to microwave radiation. Any thoughts ?

3.3V -- (R15 = 1M Ohm) -- VC@RCWL9196

Is it possible to obtain phase and power of the reflected signal from some of the pins, with additional circuitry?
I'd like to use both for additional experiments, but it's not clear to me which signals I should use.

it's 2.95-3.05 mA at 5v ;]

Hello,
I am having a very elusive problem with all five RCWL-5016 modules that I recently purchased not working when moved outdoors. Inside my garage, with the overhead door open (same temperature and humidity) the sensors work great, approximately 15 to 20 feet detection area in most of a 360 degree coverage area. When I take the same sensors outside, even on a breadboard with no other circuity, I get a reduction of almost 98% in sensitivity. I can move my hand one inch away from the board and it will light up an attached LED. My guess was RF interference, so I killed every breaker in my house (except the known working AC from my garage outlets) ran an extension cord out to my yard from the garage, and still had the same problem. So, no RF from my house, and the next neighbor is at least 80 feet away.
I noticed at the work bench that Pin 12 of the main IC was the most active by motion near the board, almost a 3 volt swing with activity within inches or several feet away from the board. Again, out in the yard I could only duplicate such a swing in voltage on Pin 12 if my hand was within a couple of inches from the RCVL-0516.
Any thoughts? Appreciate your input.
Dennis

Hi all,

My friend purchased a light bulb with a radar sensor. It lists for SGD14 (US$10) but is perpetually on sale for SGD4 (US$2.93):

E27 Sensor Radar Light Bulb

However it's detection range was too large (~4m radius). I stumbled on this project and realised the circuit and principles used are similar. Here is the circuit:

And my messy amateur interpretation of it:

The chip is a HYL-1617 (not an easy find and you need a Taobao account) which can be found for RMB0.55 ($0.09). Quite cheap, but the datasheet's only available in Mandarin. I used a translator app to OCR it.

I managed to lower the range down to 2.0m +- 0.2m by modifying the 1Mohm across the Opamp to 145kOhm. I don't have any idea how the relationship of range and resistor value scales in this circuit so I just tried a bunch of different values until I got it right. I think it works similarly to the RCWL-0516's R-GN resistor.

Anyway, just thought you guys might be interested in my little learning experience.

I had one of these connected to a rPi and it worked fine for about a month. Then I decided to hook it up to an Arduino and did not read the datasheet. I've fed 3.3V into the 3.3V and now it's seemingly dead. I did not put an oscilloscope to it to see if it actually does something, but the leds don't light up anymore and it doesn't draw any current.

I had a second module - hooked it up to an Arduino (just the 3.3V regulated out) and connected the output pin to a buzzer. It buzzed for less then a second and it went dead. Not sure if the buzzer killed it or the 3.3V.

Perhaps it would be useful to have a list of DON'Ts, such as: no voltage on the 3.3V output (without power), no inductive loads, no voltage on OUT... I don't really know what kills these modules. Static?

Hello,
I'm doing a project and this is the first time I work with sensors and I have no experience.
What is your suggestion to change the sound of a buzzer, when RCWL-0516 has detected an object? I mean, when the object is getting closer, the louder and louder sound could be heard from the buzzer.

Hi. Cool sensor. This is not an issue, but is it possible to power the radar from 3v3 without using a step up?

Hello everyone,
this is not really an issue. I just wanted to post a link to a tutorial I made a few months ago,
Hopefully it will be helpful to someone,

link: Kicklamp on instructables

Cheers,

A_

Can it be used for detecting uni-directional moving? Walking forward, back and especially parallel to the wall for example? I need to find out this issue. Could you please help? Thanks in advance.

Newbie here. I'm using an RCWL-0516 with a D1 Mini through Home Assistant to trigger a light on when someone enters a room. The issue I am having it just keeps bouncing from Detected to Clear every few seconds. This is the 2nd one I've tried with the same issue, the first one was with an ESP32. I know I must be doing something wrong or maybe there's something I need to add? Here is the ESPHome code that I uploaded to the D1 Mini. Thank you.

esphome:
  name: mw_sensor01
  platform: ESP8266
  board: d1_mini

wifi:
  ssid: "XXXX"
  password: "XXXXXX"

  # Enable fallback hotspot (captive portal) in case wifi connection fails
  ap:
    ssid: "Mw Sensor01 Fallback Hotspot"
    password: "kta0sKXAWsgS"

captive_portal:

# Enable logging
logger:

# Enable Home Assistant API
api:

ota:

binary_sensor:
  - platform: gpio
    pin: D4
    name: "Kitchen Sensor"
    device_class: motion
    #filters:
      #- delayed_on_off: 4000ms

hi @jdesbonnet
Thank you for the great work you have done for helping understand this module. I wonder how the oscillator works. It's said that the copper at the base of the NPN acts as decoupling capacitor（C=εS/d , C for Capacitor, ε for dielectric constant, S for copper area, d for PCB thickness） along with the internal resistance of the NPN, together make an RC oscillator (f=1/2πRC). It seems quite tricky for me.
Anyway, still hoping to figure out how the oscillator works.

Hello,

Do you know can this kind of radar pass CISPR 1 (EN 55015) or similar EMC standard for lighting products?

Any general idea? Thanks!

https://www.youtube.com/watch?v=Hf19hc9PtcE

I was able to modify the range to few cms 4-5 cms with 40 ohm resistance put in R9.I removed the original 221 ohm from its place.I also tried multiple resistance with R-gn but was not successful.

BUT

I am into a new problem,before any modification or keeping the resistance to around 220 ohm on the R9 resistor keeps the current consumption of the chip around 2.3 mAh but with the 43 Ohm resistance on R9 the consumption increased to 12mAh.

I am planning to keep the current consumption to be very low sine i want to run the prototype on a 4 x AA Alkaline battery which has a current of 1500 mAH give or take and with this rate the battery would die in few days.

Can someone help me with this problem,i am a beginner with electronics as i am more of a computer engineer?

Can I put something else along with the resistor to keep the range withing 4-7 cms and also draw less current?
Or
Is there any other way to reduce the power consumption of the chip by removing some pins from the IC on the board?
or
Putting a resistor before the VoltageIn pin of the RCWL will have any impact?

Please help

Hello, thank you very much for your research. How do you think, is it possible to reduce its range to 30cm or even less, by adding high resistance to R-GN?

This project is really cool. Much respect to those who have done this work.

Has anyone considered trying different Antennas? This would be a perfect circuit for a project I'm working on, but I need it to only detect in one direction (ie Field of View 180 degrees)

As it's related and there is not much information available about the "big brother" it might be a good spot here to gather details here:

Anyway, according to the datasheet the RCWL-0515 can be used at a supply voltage of 4 to 15 V, works at a frequency of 2.7 GHz and can detect objects at a distance of up to 15 metres
Source: https://www.tinytransistors.net/2020/12/20/rcwl-0515-radar-motion-sensor/

Do you guys think possible to use a pair of these sensors under the plastic rear bumper of a car, and reliably detect other moving cars within about 2.5m range?

Thanks!

Has anyone noticed a decrease in sensitivity over time? Like at first it senses motion around the corner in another room, and then two months later you have to be within six feet directly in front of it?

I have a motion-sensing non-PIR ceiling light that I installed in the laundry room which has exhibited this behavior. At first it could sense motion around a corner or through a closed, louvered folding door. Now you have to get pretty close.

I don't know which doppler module it's using, but I figured someone might have run into similar behavior with RCWL-0516-based units.

I'm wondering 1) if it's going to continue getting worse, and 2) whether it might be due to a low-quality component (resistor/capacitor, etc) deteriorating.

From the Readme:

R-CDS the VCC is in parrel connection with CDS(RCWL-9196 pin 9) through R-CDS. Connect the LDR at the R-CDS to turn off the detecting function at night. (?? TODO: make sense of this)

Perhaps this is setup to turn the detector on at night? I have a few PIR-activated LEDs around, and they spend the day charging.

I could be wrong here, still waiting for my modules to arrive.

I thought that 3.3v output PIN cab be used to drive some other sensor or something like that,but it doesn't have enough juice to drive sensors.
So I put the pin to good use by connecting to GPIO of ESP and detecting the failure of the sensor. Incase if the sensor is not working or failed for some reason, we will have no power at 3.3v pin.

Thoughts about this ??

I'm interested in adding some parts to the subject board for my own purposes. I want to perform the layout of my new portions of the circuit that I need in order to create an entirely new board, however, I would prefer not to have to reverse engineer the microwave part if someone else has already done it.

Thanks!

I used this sensor to generate digital output to drive the relay using microcontroller. But the problem is whenever relay get triggered I got false alarm which trigger the relay instantly. I tried to ignore the false alarm for 4 second but still it cause problem and i do not want to add 4 second ignore time. Please suggest how should I fixed this.

I want to switch ON a MOSFET when the OUT Pin of RCWL 0516 goes High and switch off MOSFET when it's Low.

I connected the OUT pin directly to the gate of a MOSFET, but the MOSFET is not completely ON.

My Input voltage to RCWL 0516 is 6.8V, 4 mA.

Connected Load is LED.

MOSFET used is 5N50 ( 500V, 5 A). TO 220 package.

Please suggest.

Hi,

This is actually a general question for radar/microwave detectors but the RCWL-0516 was the smallest one I could find with a quick search online.

Does anyone know if it can cause disturbance to other electronic? The questions is asked since I'm searching for a way to detect motion from inside an enclosement where other electronics is placed.

Grateful for any support!

Hi there and many thanks for the research put on this nifty radar module.
I'm trying to put this module in non-retriggerable output, as mcu's interrupts won't be triggered again if the movement continues.. Output pin will stay always high if default re-triggerable mode is active and circa-continuous movement is detected..
I analyzed pin 1 (supposed mode selector) but it seems to connect 3.3V internally regulated voltage to the BJT's collector, de facto putting this pin to ground disables the entire chip (short to ground).

I have also used the CDS pin to disable the chip, but in disabled mode it won't put the output pin LOW.

Does anybody have a suggestion on how to change detection behaviour ?
Kind regards

I've done some analysis of the analogue voltages on various pins on the IC, and the most useful is pin 12

I looked at the input voltage from the oscillator, into the main IC, but its hard to analyse as it stabilises at about 400mV, but only had about 4mV of rise and fall.

Pin 12 is the most useful for direct connection to a MCU's analogue input, as it stabilises at around Vdd 3.,3V/2 and swings between 0V and 3.3V

However the problem with using the output of the opamps in the IC is that IC effectively operates as a differentiator, so only changes in object position get propogated, and in stead state the voltage on pin 12 returns to Vdd / 3 no matter whether you are standing 10m from the detector or have your hand over it.

I have written a blog post and included various plots taken from pin 12

http://www.rogerclark.net/investigating-a-rcwl-9196-rcwl-0516-radar-motion-detector-modules/

Chips like this often provide a convenient regulator. In this case the 3.3V one.

Then there will be a pin marked "VDD" that is the power input to the rest of the chip. You as the designer get to chose to use the builtin LDO, or for example, the 3.3V from a switching buck converter that you're going to need anyway.

I'm guessing you verified connectivity between the 3.3V out and the VDD pin "again?", but that is because the designer in this case decided to use the built-in LDO and not something else.

Also typo: frequncy -> frequency.

Found this very useful! I'm unsure if this has already been noted or potentially is a version issue:

The library file for eagle initially downloads in the zip as .lib, altering the file extension to .lbr brought it up and restored functionality for me. Using the current Eagle version, this may have been correct for previous versions.

Is there any way to see if there is object even if the object does not move?

Here is a nice Video about the RCWL-0516 that may be linked under "Other links, articles and contributions":

https://www.youtube.com/watch?v=IJoPkKlxFXA

Hello,
I'm planning to use this sensor as a motion detector on my project.
The sensor will be mounted on the ceiling. But as I stay in an apartment, What If someone walks on the floor above my ceiling, will it also create a false motion signal at the output?
If yes, Can I suppress the sensitivity of the sensor backside by using a metal shielding, Ground plane of PCB or any other proven method?

Sorry folks, I haven't had time to keep the main page updated lately. If anyone wants to help with that I'd be delighted to add as project collaborator.

My motion detector was triggering a lot of false alarms. I suspect the nearby WiFi router triggered these. I tried to make a sheet metal noise shielding box for the radar. However, it stopped working. I did leave about 10mm space on the bottom side. It is not sensitive to movement any more. But it does trigger sometimes when slightly moving the device, maybe my power supply clips rattle, or some electro-acoustic phenomenon. Any other ideas how to reject interference? I wanted this as small as possible as it is inside a raspberry-pi box,