Thursday night was a real treat. I got to see both Joe Grand and Kitty Yeung at the HDDG meetup, each speaking about their recent work.

Joe walked us through the OpticSpy, his newest hardware product that had its genesis in some of the earliest days of data leakage. Remember those lights on old modems that would blink when data is being transmitted or received? The easiest way to design this circuit is to tie the status LEDs directly to the RX and TX lines of a serial port, but it turns out that’s broadcasting your data out to anyone with a camera. You can’t see the light blinking so fast with your eyes of course, but with the right gear you most certainly could read out the ones and zeros. Joe built an homage to that time using a BPW21R photodiode.

Transmitting data over light is something that television manufacturers have been doing for decades, too. How do they work in a room full of light sources? They filter for the carrier signal (usually 38 kHz). But what if you’re interested in finding an arbitrary signal? Joe’s bag of tricks does it without the carrier and across a large spectrum. It feels a bit like magic, but even if you know how it works, his explanation of the hardware is worth a watch!

The demos of OpticSpy pulling data out of a seemingly solid red LED were a blast to see. I’m glad that Joe also spend time walking through the circuit:

He mentioned that he doesn’t always get to stretch his analog design chops and this was a good project for it. Likewise, I enjoy working my way through the schematic, which uses a double-stage amplifier to condition the signal from the optical sensor. The final stage is a comparator which spits out the digital signal. Not shown in the screenshot above is the FTDI chip that takes this signal and spits it out to your serial terminal.

Joe admits that it’s hard these days to find LEDs leaking data, so he got to make his own artificial sources. His demos included using the Parallax open conference badge, a laser diode driven by an Arduino, and Tomu, a microcontroller breakout board that hides in your USB port. The four trimpots allow for adjustment of the stages, something Joe had to do for the talk as the front of the room was getting blasted by the afternoon sun.

Following Joe’s presentation, Kitty Yeung took the stage. A PhD in Applied Physics, Kitty’s talent spans many areas and she is likely to introduce herself to you as a creative technologist. You may have bumped into her at this year’s Bay Area Maker Faire wearing a shoulder-mounted solar panel, but her wearable creations are well known beyond the maker community having had multiple designs shown during 2016 San Francisco Fashion Week.

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Source:: Hackaday