I think there are many situations in which a person would love to move unseen in the darkness. But that is of course not possible because the person itself cannot see what is going on around him. To solve this problem, I built this portable night vision device, which you can strap around your head. It mainly consists of a security camera, a small screen and a custom PCB, which comes with LEDs and LED driver that was provided by the Würth Elektronik eiSos Group After powering the device with a power bank, you can see a pretty clear black and white image on the screen, which represents the illuminated room in front of it. And of course, you can fine adjust the intensity of the LEDs in order to achieve the perfect image brightness. I am quite happy with the outcome of this project! So, let me show you how you can make your own night vision device at home. Let's get started! This video is sponsored by the Würth Elektronik eiSos Group The theory of operation of my night vision device is pretty straightforward. At the front, we got a camera which playbacks it's recording on an internal display. The tricky question, however, is how to create light that is visible for the camera, but not for the human eye. Every normal LED light source I got laying around, can certainly not be used for such a task. But thankfully the security camera I chose for this project answered this question by itself. Because it is actually a night-vision surveillance camera. Around whose lens some rather interesting LEDs were positioned. That is why I unpacked the small screen next, which normally gets used for rear-view cameras in cars. And continued by cutting off the power connectors of both the screen and the camera whose power wires I then directly connected to one another in order to power them all with 12 volts. Afterwards, I also cut off their video connectors, and once again soldered the exposed wires, in this case, video wires, together with a bit of solder. At this point, we can see on the screen that the camera works without any problems and through the help of the included controller, we can actually change quite a lot of settings. But that is not super important right now. Since it was much more important what happens after I turn off my lights. As you can see this security camera can still record my face in the darkness. While the camera which I usually use for filming cannot really capture my face anymore The reason is that my expensive camera comes with an infrared filter, which blocks all electromagnetic waves with a spectral range of above 780 nanometer The security camera, however does not feature such a filter and that is why the light of the infrared LEDs all around the camera lens which got activated in the darkness, got recorded. Such infrared lights can also not be seen by the human eye. And thus we found a solution to our initial problem. It is also noteworthy that the here utilized LEDs look a bit reddish, because they partly emit shorter wavelengths which lay in the spectrum of the visible red light But nevertheless, Next, I had a look at the website of the Würth Elektronik eiSos group in order to choose suitable Infrared LEDs and I found two types, which would fit nicely Both lay in the desired spectrum and feature a forward voltage of 1.5 volts at a current flow of 70 milliamps Those values would work perfectly with the LED drivers from Würth Elektronik which output a constant current of 350 milliamps in the default configuration. This way, I could place five LEDs in parallel in order to achieve the 350 milliamps current flow And also five LEDs in series since the relatively high planned input voltage of 12 volts would allow that. And the best thing about this driver is that it features a complete buck converter inside of it, which makes the circuit very efficient and easy to build. Of course, you can find more helpful information about the wiring and the PCB layout recommendations of the driver in its datasheet. But anyway, if I would use a total of 25 infrared LEDs I should get a power of approximately 2.7 watts for the LEDs which will hopefully be enough. But in order to not overexpose the security-camera later on, the driver also comes with a DIM pin To which I will hook up a 20 kilohertz PWM signal, with an adjustable duty cycle created by a 555 timer circuit This way the brightness of the LEDs can get adjusted efficiently Now with this plan in my hat, I ordered all of the components. And as soon as I received them, I started creating a test circuit consisting of two LED rows with five of them in each. I firstly powered those two rows with my lab bench power supply, In order to find out that the LEDs with the lower wavelength, emits more visible light than the ones with a higher wavelength. So I ultimately went with the less recognizable ones, and connected those for short tests to one LED driver through a couple of wires. After then also building up the 555 timer circuit and connecting it to the LED driver, it was finally time to supply power to all of the components. And as you can see here on the screen The LEDs light up without any problems and their brightness can also get adjusted without any flickering. Perfect! Last but not least I had to think about a portable power source, since the LEDs with driver and 555 timer circuit require a maximum of around 250 milliamps, and the camera with a screen around 350 milliamps at 12 Volts. That is why this USB type-c PD power bank with an output voltage of 12 Volts and a maximum current of 1.5 Amps would be a good fit. And luckily, I also had a suitable USB type-C PD driver PCB laying around. If you want to know more about USB type-C and this driver PCB, then make sure to watch the video I produced about this topic. But anyway, next I had to disassemble the camera and the screen in order to get rid of the plastic enclosures. As soon as I got to the back camera and the screen, I started thinking about how to position those components in front of my face. And thus started creating a technical drawing of my night vision device. Once I was more confident in where to position the screen, camera and PCB with LEDs and driver, I continued with the creation of the schematic for the PCB at which point I made a big mistake. As you can see here. I planned five drivers in order to power 5 rows consisting of 5 LEDs each That, of course, makes no sense, because the current stays the same in a series connection. (so at around 70 milliamps) instead of increasing to 5 times 70 milliamps, which would be 350 milliamps. That means you only need one driver for the 5 LED rows which you have to connect in parallel, in order to reach the driver's constant current output of 350 milliamps. But before I noticed this beginners mistake, I already designed the PCB, received it and soldered all of the components to it So in case you want to recreate the PCB circuit, then feel free to leave out 4 LED drivers and use some silver copper wire in order to connect the minus pole of the five LED rows with one another. But let's get back to the main topic. My PCB does not only feature a big hole in the middle for the camera, but it also comes with extra holes for later securing it to the night vision device. I used those measurements in combination with the dimensions of the camera and the screen in order to create a 3D model of my night vision device in Fusion 360, which was heavily influenced by commercial VR goggles. I then 3D printed this model with my Prusa i3 Mark III 3D printer and some black PLA filament. After around 20 hours of printing my models came to life and the PCBs also arrived. So I started soldering all SMD components to the PCB with the help of solder paste and hot air, while I used a common soldering iron and solder for the THT components. And like already mentioned I had to make some modifications before it was finally time to power up the circuits and confirm that everything works just fine. Next, I mounted the PCB onto the front piece of the night vision device with screws, guided the wires for the screen and camera into the device, reconnected those with the screen and camera and secured everything in place with a bit of hot glue. Next, I cushioned the edges of the 3D print with some foam tape, and added an elastic strap to it before I ultimately joined both 3D prints with the help of more screws. And after connecting all ground and 12 volts wires to the USB Type-C PD PCB, It was finally time to test the night vision device! Which as you can see works great! I hope you enjoyed this project. If so, don't forget to like, share, subscribe and hit the notification bell. Also, feel free to visit the Würth Elektronik eiSos Group website to learn more about their products As always thanks for watching! Stay creative and I will see you next time!
