What is it?

This is a motion-activated device that emits a bright white 160-degree, 2800 mcd led light only when it's dark. Like the similar non-motion-detection BlackOut light also available on Tindie, this device senses when the room is too dark to see well via a photoresistor. But instead of automatically turning on the light until morning comes, this motion-activated BlackOut light waits for an infrared object (like you) to trigger the light. The light won't trigger when it's light enough to see and it won't trigger unless someone passes within a few feet of the device. It is possible to extend the detection range by fitting a Fresnel lens over the D203S passive infrared (PIR) detector that is the motion-sensing element.

The device is controlled by the BISS0001 PIR controller. There is a 100 K potentiometer that determines how long (1 to ~30 seconds) the light stays on after triggering. There is also a slide switch which determines in which of two modes the BISS0001 can operate. Either turn off after a set time after triggering independent of any subsequent motion or remain on as long as motion is detected within the set time interval. These are referred to as triggering and non-triggering modes in the data sheet. The led is controlled by the output of the BISS0001 which switches on a transistor gate that enables the led. The BISS0001 output signal is also broken out along with 3V3 and GND to three solderable through holes on the side of the sensor in case some other device is to be triggered like a camera or alarm, etc.

The motion-activated blackout light accepts voltages from 2.5 to 10 V through the TPS71433 3V3 out voltage regulator and it is intended to be magnetically attached to a 9 Volt battery, but there is no end of other useful mounting options. The BISS0001 can run on up to 5 V but here the voltage is limited to 3.3 V for easier interface to the Teensy and other microcontrollers that are not 5 V tolerant. Besides, the lower the voltage, the longer the device can function without having to change the battery.

Why did you make it?

I use the BlackOut lights around the house. Even though they are designed to only be on when the photoresistor detects dark conditions, they stay on all night limiting the functional life to about two months, which is really quite long for a battery-operated night light. But there are some cases where I would like the light to be off all the time unless I am in the room or at the threshold. At the front door is one example, since we don't leave the porch light on all day I wanted to have a small portable (no wire) light that would shine light long enough when we get home after dark to allow us to easily see the door lock. I have some closets that have no built-in light and one of these devices provides light if and only if the door is opened. This is very convenient. I have put a few around the house on the inside thresholds atop the door jams and I find that having the light come on automatically when I enter a room after dark is interesting and fun (or so my kids think so) and practical too since it makes it easy to find the light switch, etc. Yes, one could just leave all the lights on and never need a motion-activated, portable night light. But there are many other uses too.

What makes it special?

This device can be used to trigger on events. You could take autonomous photos of wildlife that passes by a particular spot, or trigger video when someone comes to your door or enters a room they shouldn't be in. Basically any motion of a IR radiating body will trigger the PIR sensor and the out signal from the BISS0001 can drive subsequent action. I can think of lots more uses to put this little device, I'm sure you can too!

Order the pc boards from OSH Park and assemble your own. There are a lot of components but they are readily available and relatively inexpensive. It does take quite a bit of time to hand assemble these interesting devices (that's why the price is higher than the much larger PIR detectors you can buy on Ebay) and the 0402 passives don't make it easy for those using a soldering iron. I use low-temperature solder paste reflow on a hot plate; this should work for you. I recommend assembling your own since it is relaxing and rewarding to build something and then make use of it. But if you don't have the time, just order the fully assembled and tested motion-activated BlackOut light from me and see for yourself how versatile and useful motion activation can be!