RadSense 1

Radsense 1 is a presence sensor that actually knows if you are present. Using a low power millimeter radar it can detect millimeter (0.04″) movements. Any human or animal within the detection zone will trigger the device – as long as they are breathing. Since it’s based on Radar technology, it will trigger even when mounted behind a wall or other installations.

RoHS/REACH

The simplest way to understand what you can do with the Radsense sensor, is to imagine what you could control using a pair of buttons. You can control lights, a DC motor, a vibration motor, a solenoid, a buzzer, audio effects, video playback, a fan or anything else that can be controlled using DC power. Just connect a wire to the screw terminals and the device will make or break the connection based on the presence of a person. Adjust the trigger distance using the supplied screwdriver.

The initial idea for the product was to make a solution for controlling video playback using a Brightsign video player. When showing a video, you’ll often want to show a video attracting people to the screen. When they have been attracted to the screen, you want to show something else. A good example is for a museeum or exhibit where you’ll show a silent trailer to attract the users attention. When they move closer, you’ll switch over to the movie itself with Audio enabled. Once the user moves away, the player goes back to showing the trailer and thus not providing any more noise pollution than required. You can see a video of this setup here and we’re working on a full tutorial for how to connect this up.

Since the sensor is based on radar, it will see through most materials, so you can mount it inside furniture, behind a window or a wall. Combining the sensor with an audio player, you can make audio experiences that surprise the audience while being vandal resistant. Ever wanted to attract focus to your window display as people walk past? Why not make a display light up when someone is in front of it? Anything that is low voltage can be turned on/off based on presence by just connecting two wires.

This device can make or break a connection – depending on how you connect it to what you want to control. A suitable tiny screwdriver & USB C cable can be found inside the wall of the box your Radsense came in (just unfold it). Cut one of the wires on your device and connect the two ends to Output 1. Mount the sensor – either using screws or the builtin DIN rail mount. Plug the USB cable into the device and a USB charger and you’re ready to go.

Use the LED feedback to see when you enter the detection zone (3m/9ft). If any person or animal is moving a millimeter in the detection zone, the device will detect this and close the builtin relay. Millimeter detection will detect minute movements such as someone breathing. For details on setting up the device, click here to go to the Setup pages.

In most cases, the device will do what you want out of the box. We do however offer the ability to customize the device completely for those with the required skills. At the heart of the device is the popular ESP32 C3 microcontroller. If you know how to program a microcontroller using Arduino, you can replace the firmware with your own. We provide a tutorial on how to update the original firmware, schematic and pinout for those that want insight and customizability.

Using this flexibility, you could make the device report presence to any other system with a wireless connection. You could build custom detection system to trigger alarms when someone enters the server room or your garage? Want to integrate it with Home Assistant or similar systems? We got you covered. Need a custom, hands-free solution to measure distance/height? Write code that prints the distance out on a screen using the builtin STEMMA connector. Don’t like the way we measure? Write your own algorithm. We don’t lock you down in any way.

If you know electronics, we also have some convenient features built into the circuit board, so feel free to use the supplied screwdriver and have a look inside?

Combine the sensor with a small computer such as an Arduino or Raspberry Pi and only your imagination is the limit. In fact – the device itself is a microcontroller with both WiFi and Bluetooth BLE and everything about it is open. This means that if you know how to code, you are free to change the code in the device itself and to customize it just as you like.

But speaking of limits – there are some that you should be aware of. The relays on this device (G6K-2F-Y-TR) are small. They can only handle up to 60V DC at 0.5A or 30V DC at 1 Ampere. The device is designed for DC voltage only. This means that you can use the device to turn a 12V light on/off, provided that the light does not consume more than 12W. If you try to use it with a more powerful light source, you may damage the device or even cause a fire. Do not connect the device to AC voltage. Technically speaking, the relays can handle 125 VAC at 0.3A but the circuit board is not made for this, so do not use Radsense1 with any AC source.

It is not impossible control more powerful devices based on AC though. It just means that you cannot control them directly. You can safely use the Radsense device to toggle 110V devices using an IoT Relay (US only). We have not found a 230V variant of this product, but if you hire an electrician to connect it up (accoding to local rules where you live), you could use a lot of products such as the Shelly Plus, Sparkfun Beefcake DIY kit and many other relay modules.

Toggle one or two relays (max 1A/48V) based on distance
LED feedback for setting up. Precise setup via Bluetooth also available
Adjustable relay modes and sensistivity levels
Set trigger distances using the enclosed screwdriver (no programming required) – Trigger range 300 mm (10 feet)
Hackable hardware and Open Source Software
Can be mounted behind plaster, wood, plastic and other non-metallic materials within certain limitations.
Detection range: 0-300cm (0-9 feet)
Detection angle: 60 degree
Power supply: 5V USB (1000mA minimum)
Power consumption: 205-250mA (indicator LED off/on)
Weight: 60g / 2.1oz
Dimensions (L/W/H): 100 x 54 x 33 mm (4.0 x 2.1 x 1.3 in)
ABS plastic enclosure with screw and DIN mount
Radar frequency: 24GHz ISM band, 0.231mW. Compliant with FCC and CE spectrum regulations
Max. switching voltage: 48 VDC
Max. switching current: 1 A

Why would you use this over a PIR sensor or an ultrasonic sensor? This comparison can be a good guide.

Detection Method	Continuous Presence	Through Materials	Setup Complexity	Power Usage
RadSense 1 (24GHz Radar)	Yes – detects breathing	Yes – plaster/wood/plastic	Simple relay connections	1.25W
PIR Motion Sensors	No – turns off when still	No – line of sight only	Plug and play	0.5-1W
Ultrasonic Sensors	Limited – small movements	No – direct path needed	Moderate wiring	2-5W
Camera-Based AI	Yes – computer vision	No – visual required	Complex programming	10-50W
Pressure Mat Sensors	Yes – weight detection	No – physical contact	Simple connections	1-3W

Another thing to consider is that compared to a camera based sensor, you get solid detection without any GDPR issues. Only presence is detected, not anything related to the person itself.