Category Archives: Aggregated

App note: General overview of IR transmission in free ambient

via Dangerous Prototypes

an_vishay_general

Vishay’s general information about IR transmission in free ambient. Link here (PDF)

Free ambient IR data transmission, IR remote control as well as most opto-electronic sensors and light barrier systems work with an optical wavelength between 870 nm and 950 nm. The emitter and detector components are highly efficient in this near IR wavelength band and can be manufactured at low cost.
Data transmission in free space demands high interference immunity of the IR receiving modules. The receiver unit, waiting to receive signals, is bombarded with different optical and electromagnetic noise signals, which are omni-present in the ambient or generated by the electrical appliance itself. All optical sources with an emission spectrum in the reception bandwidth (830 nm to 1100 nm) of the detector can be considered as disturbance sources. These are mainly fluorescent lamps, incandescent lamps and sunlight. Many plasma displays can also produce significant emissions in the optical band of the IR transmission.

Free PCB Sunday: Pick your PCB

via Dangerous Prototypes

IRToy

We go through a lot of prototype PCBs, and end up with lots of extras that we’ll never use. Every Sunday we give away a few PCBs from one of our past or future projects, or a related prototype. Our PCBs are made through Seeed Studio’s Fusion board service. This week two random commenters will get a coupon code for the free PCB drawer tomorrow morning. Pick your own PCB. You get unlimited free PCBs now – finish one and we’ll send you another! Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • Be sure to use a real e-mail in the address field so we can contact you with the coupon.
  • Limit one PCB per address per month please.
  • Like everything else on this site, PCBs are offered without warranty.
  • PCBs are scrap and have no value, due to limited supply it is not possible to replace a board lost in the post

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App note: Using Vishay infrared receivers in a Wi-Fi environment

via Dangerous Prototypes

an_vishay_usinginfraredreceiversinwifi

2.4Ghz and 5 Ghz Wi-fi signals can sometimes affect IR receivers, here’s Vishay’s app note about them. Link here (PDF)

In recent years, Wi-Fi connectivity has penetrated most consumer electronic devices used for media reproduction. New TVs, satellite receiver and cable boxes, and streaming devices are more often than not built with Wi-Fi capabilities at multiple frequencies: 2.4 GHz and 5 GHz. Most of these appliances continue to support an infrared (IR)-based remote control link, often even when the device also supports a newer RF-based remote control.
IR remote control receivers are built with highly sensitive wideband input stages and are able to detect signals near the noise level of their circuitry. In noisy environments, such as with both low- and high-frequency electromagnetic interference (EMI), the receiver may be noise-triggered, typically manifesting itself in the form of spurious pulses at its output. Most Vishay IR receiver packages are designed with metal shields to effectively guard the receiver against low-frequency EMI. However, these metal shields have not proven entirely satisfactory against high-frequency EMI in the GHz range used for Wi-Fi.

Winner, Name that Ware August 2016

via Hacking – bunnie's blog

After reading through the extensive comments on August’s ware, I’m not convinced anyone has conclusively identified the ware. I did crack a grin at atomicthumbs’ suggestion that this was a “mainboard from a Mrs. Butterworth’s Syrup of Things sensor platform”, but I think I’ll give the prize (please email me to claim it) once again to Christian Vogel for his thoughtful analysis of the circuitry, and possibly correct guess that this might be an old school laser barcode scanner.

The ware is difficult to evaluate due to the lack of a key component — whatever it is that mounts into the pin sockets and interacts with the coil or transformer near the hole in the center of the circuit board. My feeling is the placement of that magnetic device is not accidental.

A little bit of poking around revealed this short Youtube video which purports to demonstrate an old-school laser barcode mechanism. Significantly, it has a coil of similar shape and orientation to that of this ware, as well as three trimpots, although that could be a coincidence. Either way, thanks everyone for the entertaining and thoughtful comments!

Free PCB coupon via Facebook to 2 random commenters

via Dangerous Prototypes

BP

Every Friday we give away some extra PCBs via Facebook. This post was announced on Facebook, and on Monday we’ll send coupon codes to two random commenters. The coupon code usually go to Facebook ‘Other’ Messages Folder . More PCBs via Twitter on Tuesday and the blog every Sunday. Don’t forget there’s free PCBs three times every week:

Some stuff:

  • Yes, we’ll mail it anywhere in the world!
  • We’ll contact you via Facebook with a coupon code for the PCB drawer.
  • Limit one PCB per address per month, please.
  • Like everything else on this site, PCBs are offered without warranty.

We try to stagger free PCB posts so every time zone has a chance to participate, but the best way to see it first is to subscribe to the RSS feed, follow us on Twitter, or like us on Facebook.