18 Feb Meeting Recap


Wow, what a great meeting… Great crowd (despite my last minute announcement), great projects, and great discussion with other Makers.

As unprepared as I was, everyone else brought in cool toys. Ken made an Arduino-based animated LED heart valentine for his wife. He uses the “charlieplexing” technique, in which you try to drive as many LEDs with as few wires as possible. Only one LED is lit at a time, but you cycle through them so quickly that the human eye can’t tell. Looks great already, but we talked a little about resistor choice to brighten the display. By the end of the meeting, he had resoldered it to double the brightness. We also suggested that he add some sort of a light sensor, so it can conserve battery.

(in case the embedded video doesn’t work, check here http://flickr.com/photos/npj/3291388819/)

Walt (of Hacktory fame ;) brought in his impressive Arduino-based display. The arduino is pulling image data from the flash chip (center, bottom row), and writing row at a time to the LED drivers (three of them, center row), who in turn drive the LEDs. I think he said he has four levels of grey for each LED, and has a refresh rate of about 50 frames per second.

Walt's high-rez display

In this video, Walt showed how this thing really rocks. Image data is from some flickr group about pictures of words.

(in case the embedded video doesn’t work, http://flickr.com/photos/npj/3291388823/)

Walt wants to build these as modules, 16×8 each, that can be plugged together to build a huge display. He wants to offload most of the signal generation from the arduino onto a programmable oscillator. Excellent project, and I want to help where I can.

Also, Walt mention an excellent supplier for those 8×8 modules seen in his project. Anyone remember the link?

We had been talking about dismantling a scrap TV for a while.  With the impending change to digital (has it happened? what’s up?), we figured there would be a lot of these in dumpsters soon, so it would be nice to know how to SAFELY dismantle and extract useful parts.  I took the power transistors, rob took the potentiometers.  And I put the tube on my officemate’s desk for the surpise on his face in the morning.

Dismantling the TV

PLEASE PLEASE PLEASE be cautious, and don’t open a TV unless you know how to discharge it’s power supply.  If you don’t know what that means, don’t open a TV, even if it’s been unplugged for years!

Good stuff.  I’m glad to hear Ken’s success with the Arduino, and I look forward to Walt’s manufactured wall-o-LEDs.

Next meeting in two weeks!


2 Responses to “18 Feb Meeting Recap”

  1. Ken Says:

    The source Walter recommended for the LED modules was futurlec.com

  2. Ken Says:

    Ack! You forgot to mention the brief interlude where we played retro Atari games; Missile Command and Breakout.

    I had in my bag of tricks a stand alone Atari classics 10 in 1 joystick [http://www.amazon.com/o/ASIN/B0000645DD/cheapandtiny-20/ref=nosim/]. I was thinking it could provide an RF signal to the TV before we tore it apart, but we had no RF converter.

    Nick immediately wanted to dissect it, and I agreed as long as it went back together. It is amazing how what once fit inside a console and at least 10 cartridges now can be compacted into a slightly oversized joystick (most of which was taken up by batteries).

    Once back together we then plugged it in to the overhead projector and played Missile Command. Nick lamented as to how everyone was better than he, but I showed him up by getting ZERO points in Breakout.

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