Can remote control IR LED's and reciever work as motion sensors ? - Page 1
Forum section: electronics / beginners

author: MathWizard
author_rank: Super Contributor
timestamp: July 12, 2022, 02:49:09 pm
content: I have the IR TX/RX components from some old TV's. If you point an IR LED at a little spot of reflective paint, like on a wall a few feet away, and u have the IR RX there next to the TX, would they be good enough to use as beam break sensors, through a glass window to an outside wall ?If that worked, I could have have 2 beam break sensors, separated some, like on the ends of a window, or 1 on each window, and then with some analog circuitry or a MCU, I could make a super cheap motion sensor/alert that someone walked past my garage.I have a little laser diode from a saw too, but that would make visible red dots tho. What about beaming ultrasonic through glass to an opposite wall ?Or what sensors like these, would they work from inside through a window ?https://www.amazon.ca/DAOKI-Detector-HC-SR312-Pyroelectric-Automatic/dp/B07XF62F9J/ref=asc_df_B07XF62F9J/?tag=googleshopc0c-20&linkCode=df0&hvadid=560405685064&hvpos=&hvnetw=g&hvrand=10200176400603459412&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9000015&hvtargid=pla-942741148282&psc=1***And yes I could get outdoor motion sensor lights, but then I'd trip them, or have to turn them off sometimes, and that's not what I want all the time. At some point I'll get a camera, but good ones are expensive, or IDK, I'm just looking on amazon and I don't like most of those.Ok little indoor cameras are pretty cheap, I could get some of them for now, but it's still really hard to find them that work on PC, not a phone, and that are not some cloud thing, and have night vision, and then can they see through glass.........why is buying stuff so hard

author: inse
author_rank: Super Contributor
timestamp: July 12, 2022, 03:50:59 pm
content: The PIR sensors will not work through a window as glass would not pass the far infrared.In theory, a light barrier could be made of remote control parts, it's mainly a question of optics to get this working reliably.And you need to check whether a remote control is capable of continuous operation.If you are having fun in experiments, go for it.

author: Benta
author_rank: Super Contributor
timestamp: July 12, 2022, 04:55:20 pm
content: You need to treat IR remote TX/RX as visible light, although you can't see it. And you need to match the wavelengths, typically 870 or 940 nm.This means that normal optics as for visible light can be used to focus your IR TX device.PIR is a completely different story.

author: tooki
author_rank: Super Contributor
timestamp: July 13, 2022, 12:27:30 am
content: FYI, check out the Vishay website. The section on IR products has a massive library of documents (app notes, white papers, design guides, etc) on IR applications. I think you’ll find that using components optimized for the task will be better than pressing IR remote components into service.

author: Benta
author_rank: Super Contributor
timestamp: July 13, 2022, 12:36:07 am
content: Quote from: tooki on July 13, 2022, 12:27:30 amGood tip. Vishay is awesome on IR.

author: Ian.M
author_rank: Super Contributor
timestamp: July 13, 2022, 02:10:06 am
content: The remote control IR receiver module wont respond to a continuous signal, so you need to modulate the IR transmitter LED with something it will respond to. Typically this involve pulsing the LED at whatever carrier frequency the receiver prefers e.g. 38KHz, and further breaking up the pulses into grouped bursts, of whatever burst length and interval between them the receiver module datasheet indicates it accepts, usually a fairly low duty cycle. You can do this with a few lines of code controlling a driver transistor attached to the PWM peripheral of a MCU, or with something as crude and simple as two 555 timers, one pulsing the LED at the carrier frequency, and the other inhibiting the first periodically to break its output up into bursts.

author: MathWizard
author_rank: Super Contributor
timestamp: July 13, 2022, 02:56:58 am
content: Ok so those little IR modules or LED's in my junk bin probably won't work for that, I should try them indoors in a hallway. I didn't mean I'd use the remote control encoding, I just mean the LED and photo-transistor or what ever it is. Other than that I only have cheap little photo-resistor's, they work ok as light level sensor, but yeah I never tried pointing an LED at them from any distance.So a cheap webcam would be better than anything in my junk bin. I'd still like some basic analog sensors for outside tho, even if I just hack a little AM transmitter to classic motion sensor lights. I'll have to read some old DIY blogs, and EE magazine articles.Or I could tie some tin cans together and run fishing line......or line the walkway with really loud bubble wrap.

author: ejeffrey
author_rank: Super Contributor
timestamp: July 13, 2022, 03:13:46 am
content: The standard IR remote control transmitters use modulation because the receivers are AC coupled in order to reduce sensitivity to background light. The optical filter blocks most visible light, but things like incandescent lamps or sunlight put out a ton of near IR. So the transmitter is modulated at 38 kHz and the receiver is AC coupled or maybe bandpass filtered to block the background light at DC and low (60/120 Hz) frequency, then rectified. If you want to use IR receivers as a bream break sensor you almost certainly want to implement something similar.

author: gamalot
author_rank: Super Contributor
timestamp: July 13, 2022, 06:59:07 am
content: I happen to be working on a small project to transmit data with infrared. I use a STM32L011 to control the infrared LED, two timers are cascaded to generate 1200 baud rate data and 38KHz carrier. On the receiver side, there is nothing more to do than 5V to 3.3V level shifting. They work just fine, although both the IR transmitter TSAL6200 and the receiver HS0038B are very cheap clones bought from China.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 13, 2022, 02:09:31 pm
content: The first issue is that IR does not pass though glass well. Just go stand outside and try to turn over the channel on your TV through a window.Second issue are the peculiarities of those integrated IR module's. For best results yo have to modulate your carrier wave (usually 38 to 40-odd kHz depending on the module used). But there is more to it. At least some of those integrated modules try to be smart, and when they see a continuous carrier wave, they assume something is wrong and they reduce gain in an attempt go get some coded signal.But is it really worth it to build your own?You can get a completely built photocell sensor set with a 4 meter range for around EUR10, and that is inclusive a box and attached cable.