HFS-DC06 radar sensor question

I'm playing around with a somewhat popular radar sensors, HFS-DC06. These are suppose to sense motion (kind of like PIR sensors, but by emitting RF instead of only sensing it. They are wired with +V, GND, and an output pin that is suppose to be high for motion and low for no motion. Here's the link:

On the HFS-DC06 I have, I've tried supplying both 5V and 3.3V on the Vcc pin, but having the same issue regardless of supply voltage; the output pin is high (4.6V) normally when powered on and no motion. My unit only senses motion once after power on, in which the voltage drops to around 0V for a few seconds, and then goes back to high (4.6V) and stays there forever even if there is motion. I need to remove and reapply power for it to sense motion again, and then it only does so once. Aside from that, the voltage level for motion/no motion seems backwards from what others report. But I've double checked to make sure my wiring matches the PCB marking.

I couldn't find anything on google about this device behaving like this. Seeing if anyone has had experience with this sensor and maybe have seen same issue? Or if my symptoms are telling?

My power supply is the Vin pin from an ESP8266, using jumper wires to put some distance between the ESP8266 and the sensor in case that matters.


I dont know whether I got what is your problem. but with ESP8266 I had problem of supplying enough power to the externel device and hence my sketch was not able to upload properly..

I wanted to update to this topic since I was unable to find the information I have discovered through experimentation.
I also have the HFS-DC06. The information I had read on this was that it would work from 5v to 12v.
I had even seen one report of someone using 3.3v with it.
My experience is not the same.
At 5v it behaved oddly. It would power up but it either wanted to stay in "detect" mode (output =HIGH) or it would not detect at all.
On a whim I ran my Arduino 5v output through a buck converter and took it to 6.5v.
The sensor now actually worked ... sort of. It seemed to have very little sensitivity adjustment, could only detect a few inches from the sensor and would some times still just stay "on".

Some of my reading showed this sensor as being rated for 6 - 12v.
So I hooked it up to a 12v bench supply and like magic ... it works wonderfully.
At least in the lab.
I have yet to test it out in the field.

So if anyone else is struggling with this sensor ... you might try taking the power input up to 12v.
Oh ... I also had to use a "pull-down" resistor between ground and the Arduino input pin, to stop the false trigger signals. That has less to do with the HFS-DC-06 and more to do with "random signals on empty pins" (which you can find elsewhere in the forums) but that is an Arduino phenomenon that could make you think the sensor is faulty when it is not.

Good luck.

Hello Gary,
Clipped from your post below;
"also had to use a "pull-down" resistor between ground and the Arduino input pin, to stop the false trigger signals. That has less to do with the HFS-DC-06 and more to do with "random signals on empty pins"

Does that mean I need to attach 10k resistor to the
HFS-DC06 out pin and ground pin to stop false triggers?

Feel free to post a data sheet of that sensor, that'll be telling how to read it.

HI,Glad u guys are interested in HFS-DC06 this type of sensor,we are the original manufacturer of this sensor in Shenzhen China.
For this sensor, have three optional input voltage : DC5V、8-15V、12-30V(input voltage need to go through voltage stabilization)
and the attached is the working principle and specification for your reference.

By the way, Can I ask in which application you use it with ?
Appreciate your kindly reply.

more information, just contact me by mail erin7903@aliyun.com or whatsapp: +86 15019491730 thanks.

Specification HFS-DC06.pdf (214 KB)

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Hello dear Erin,
In the product search we found the radar sensor HFS-DC06 in the Arduino forum and also your email address for questions....but we become no response.

.... now we need your help here:

Our system has 12V / 100Ah or 5V to provide high current via DC-DC buck converter. Both voltages have the same negative ground.

For testing we bought 2 pieces of the sensor and connected the 5V to the GND / VCC and the OUT at the input-pin of the Arduino.(without pull-down-resistor)
Before that, we read the data sheet carefully.

The green LED signaled: At the first power on will output high level indicator lights will be on, 2 seconds to low level, followed by 6 seconds ... all okay.
But there is no output signal, no matter how the time or sensitivity has been adjusted.
Then we connected the sensor to 12V and it's totally destroyed (no reaction, led off, hot case, smoke). -> scrap.

  1. Must the sensor not be connected to 12V or only to 5V ?
  2. Or is it a guarantee case?
  3. Is the description wrong witch declares 12V as supply-voltage ?

Then we took the second sensor and reconnected it to 5V and everything works as desired.
However, we can only see about 1-2 meters, although we need 10-12m.
If we increase the sensitivity, the output switches permanently  therefore not usable.

  1. What are we doing wrong ?
  2. Or is this sensor also defective ?

We would be very grateful for an answer to the 5 questions .

Sincerely yours