[align=center:]Dangerous Prototypes TTL Logic Contest “Electronic “Kvetch-A-Sketch with 32-Page Flip Pad” Submitted by Eastern Star Geek, Johnson City, Tennessee USA[/align:]
This project is an electronic interpretation of the famous Ohio Arts “Etch-A-Sketch” toy, with a twist. Like the original, two rotary knobs are used to move a cursor horizontally and vertically, respectively, but unlike the original, a third knob selects one of 32 different sketch pages. Simple flip-pad animations can therefore be created by twirling the page knob rapidly.
The screen is built from four 8x8 dual-color LED matrix displays, for a total screen area of 16x16 pixels. The artist has a palette of three colors from which to choose- Red, Green and Yellow.
The three rotary knobs are quadrature encoders with a built-in pushbutton.
Several toggle switches and pushbuttons give the artist the ability to: 1. Draw dots, either continuously, or one at a time, using the built-in pushbutton in the X knob. 2. Erase dots, either continuously, or one at a time, using the built-in pushbutton in the Y knob. 3. Choose the color of the dot(s) to be drawn or erased 4. Choose between Edit and Playback modes (Cursor is turned off in Playback) 5. Clear the current page 6. Go to the “Home Page” using the built-in pushbutton in the Page knob.
This project is from an original idea by the author, and was designed and created from whole cloth especially for this contest.
They are excellent Point-of-Load (POL) power supplies. I am using it for a building control system where I have to take sloppy Thermostat control voltage (18-24VAC) and clean it up enough to use a microprocessor, relays and allied devices.
Keep in mind that this is an un-isolated three-terminal device, and they're not cheap- but it's perfect for my application so I bought it anyway.
"You can get it Cheap, you can get it Good, or you can get it Quickly. Pick any two!"
I also have a Weller soldering station, of exactly the type you mentioned. The regulation method is really quite clever- buried in the tip is a permanent magnet that has been formulated to have a Curie point http://en.wikipedia.org/wiki/Curie_point equal to the desired temperature. In the barrel of the iron is a magnetic (reed?) switch. When the iron is below the set temperature, the magnet pulls in the switch, energizing the resistance heater. When the Curie temperature is exceeded, the magnetism goes away, the switch opens, and the iron cools. Rinse, wash, and repeat!
The nice thing about my dimmer is that I can crank it all the way up to rapidly heat a cold iron, then dial it back to any number of arbitrary marks. When the heat lost by the iron equals the heat gained by the element, the iron's temperature will stop rising and reach equalibrium. More power in raises the equalibrium point. I find this suffices for soldering small items that have a low thermal mass compared to the tip.
Obviously, there are plenty of situations where precise closed-loop control is necessary, but I rarely do that kind of work (mostly because my eyesight is so poor!)
OK, so here's a quicky solution to a recent problem:
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Here you see an XYTronic 200GX iron that I purchased at a local commercial supply shop for US$19.00. It's a good iron with very nice interchangeable tips, but it runs way HOT at it's rated voltage of 120VAC.
The solution is a Lutron 500W incandescent lamp dimmer, junction box, neon panel lamp and hacked extension cord- all of which cost me about $16.00 at the local Home Improvement store. Yes, it's ugly, and it is open-loop control, but it does the job.
As a side benefit, it works great with my Dremel tool, also!
BTW, if you find this useful, please drop me a line and let me know!
I also posted a video showing a fun little toy that displays Temperature and Humidity on a scrolling 3-digit LED 7-seg. display. Lots of useful examples in the code, too! http://easternstargeek.blogspot.com/201 ... ensor.html
Stay tuned!
PS: Hearty thanks to NashblackCat for giving me the incentive to finally get off of my Old-Skool ass and start up my technology blog!
