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Searching for: electronics


Time to finish that languishing clock project! [01325805161]
A leap second has been announced at the end of June 2012.

Side track: wwvb links [01308865139]
Chris asks what advantage GPS has over WWVB for my clock project. I don't have a good answer for that (except that having enough controls to select one of 4 mainland US timezones and whether to apply DST is undesirable). However, this did prompt me to do some googling about WWVB. I found some interesting links about generating WWVB signals at home.

Soldering "helping hands" made with Loc-Line coolant hose [01265413640]
(M)(L)Two-part clamp grips circuit board I ran across "Third Hand" and decided to make my own. The main feature of my version is the two-part circuit board clamp. The clamps were manufactured with Chris's help on Jr, his new cnc milling machine.

Arduino Random Number Generator [01257868826]
Random Number Generator Schematic Inspired by other designs I've seen online, most directly Rob Seward's design, I decided to build my own random number generator based Will Ware's "avalanche noise in a reverse-biased PN junction" (try this mirror of Will Ware's page). Also important is turbid which introduced me to the concept of hash saturation and the math behind it.

Two-element capacitative touch sensor [01219970985]
(M)(L)Touching the sensor (M)(L)The finger position readout As a distraction from my real project -- building a lightbulb alarm clock for the coming winter -- I've been playing with capacitative sensors. My first effort was a wire taped to a piece of metal foil, and that worked OK. The present iteration is a two-element touch sensor on a milled circuit board. The sensors are each about 1" by .5" and are connected to the arduino by a 3-pin header. The components on the board are very simple -- two 1M resistors. With a combination of software running on the microcontroller and in the PC, the sensor is made into a virtual slider.

Bah, it's garbage [01210042966]

1MHz+ Quadrature Divider for attiny13 [projects/01149348342]
Quadrature divider board. Actual size: .7x.4 inches (about 18x10mm) This untested code, along with an Eagle schematic and board layout, are for a quadrature divider that polls at over 1MHz. The R and S test points are used to program the device. Like the 400kHz triple divider, this program uses a state table generated by "mkstate.py", and is GPL software. For real-world use, external pull-ups should probably be added to the board's input side, according to the directions of the encoder manufacturer.

400kHz Triple quadrature divider for atmega8 and quadrature state table generator [projects/01149271333]

Creating a Quadrature Divider: What Won't Work [projects/01149094674]
A proposed quadrature divider circuit, and a waveform that it will treat incorrectly As an improvement to the simplest possible closed-loop servo system, I've been trying to design a circuit that will function as a quadrature divider: the input and output are both quadrature waveforms with the same direction, but the output waveform is 1/8 or 1/16 as fast as the input. Because emc2's encoder module poops out somewhere around 20 microsecond polling intervals, an external divider is the only way to get accurate feedback from a fast servo motor with a high-resolution encoder. Division by 16 lets the PC see a 25kHz quadrature signal instead of a 400kHz one. For Chris's lathe retrofit, the target speed is actually around 125kHz (1250 mm/min, 1mm/rev leadscrew, 3:1 pulley, 500 line/rev encoder), but to keep it from being too easy, he's going to do 3 such decoders on a single 16MHz atmega. Many people seem to hit on the idea of using an up/down counter to process a quadrature input. Chris and I managed to convince a couple of bright guys on the #emc channel that this would work to create a quadrature divider circuit. Well, it doesn't.

Two-axis servo schematic and board [projects/01148303608]
L298 single-sided board I didn't originally include the eagle-format schematic and board for this project. Well, here it is.

Parallel-port Two-axis PWM servo controller for Etch CNC [projects/01142347802]
(M)(L)ETCH Servo Inspired by discussion on #emc and by the fact that I'd already bought two tiny servo motors, I've designed and built a two-axis PWM servo controller with a parallel port interface.

First Interesting Strobe Photo [01135347558]

SOIC-8 to DIP adapter board [projects/01134834815]

4-axis half-stepping translator in AVR [projects/01129403515]
Chris started with a MAXNC 10 open-loop machine. The included driver boxes (which we came to understand were complete crap) use one pin per winding. This requires two parallel ports for 4 axes. So, a year or so ago, before he switched to L297/8-based boards, I helped Chris design an avr-based translator from step+direction pulses to the individual winding activation signals. Today I'm posting the program, which I compiled with avr-gcc. In the future I might post the board, which was a double sided design created in eagle.

a plug for Eagle3D [01117938653]

XY display update [projects/01117067802]
New CRT, new board, same software...

vgaxy -- create XY scope displays with your VGA card [software/01115603899]
Software for a virtual terminal and several other toys

Vector patches for xmame 0.94 [software/01115603825]
With this patch applied, xmame 0.94 does vgaxy-style output for display on an oscilloscope in xy mode

More vector game screenshots [01115494353]
(M)(L)Battle Zone I really should mention the website of Jed Margolin which has a lot of information about his time at Atari, including his work with vector games.

"Dithered" output increases resolution [01114979771]

MAME vector display on the oscilloscope [01114971365]
(M)(L)Asteroids Yep, it works. Too bad about the low resolution. More game pictures below the fold.

Working Z-axis [01114736689]
(M)(L)Vector terminal with Z-axis With a simple transistor, the Z axis works pretty well. The linearity is better now that I'm using some 10b2 tees and terminators (50 ohms) on the X and Y inputs, too.

Vector "text" display [01113752862]
(M)(L)Simulating a character-cell display Displaying a message, even.

Animated XY display [01113705217]
(M)(L)Not originally a raster game... It's an old-style "QIX" animation.

VGA to 'scope display [01113670404]
(M)(L)XY display of a cube The question on my mind was this: Where do I get a nice, fast DAC to run an XY display? How do I keep it fed with values? I discovered a very simple answer that I hadn't heard of before. The hardware is dirt simple: Get a VGA to 5 BNC-connector cable. Plug your computer's VGA output into your scope. Now load a specially crafted image in a full-screen viewer

Regulated LED flashlight -- update [projects/01112559552]

TI serial-interface DAC [projects/01112140655]
(M)(L)Sine wave created by software running on an AVR with a look-up table I got this interesting little DAC working earlier tonight, with only a minimum of trouble. The code worked right the first time, but I got the hardware wrong ---I let the "power down/" pin on the DAC float, which meant I got a mostly random square wave superimposed on the sine wave. Here's a crummy photo of my scope displaying a sine wave. The sine wave is generated from a 512-entry, 9-bit table in the AVR.

Regulated LED flashlight [projects/01111764189]
This new board is designed around the same MIC2570 boost-mode regulator, and is designed to fit inside a pocket-size tin.

Another constant-current circuit [projects/01111254927]
Here's a constant-current LED driver circuit meant for use with wall-wart power supplies

It's in a frame! [01109127822]
OK, so there are still some problems left. But this is exciting anyway.

Stippler: Turning photos into dots [01108611472]
A few weeks ago, I stumbled over a paper by Adrian Secord describing an algorithm to turn a greyscale image into stipples. Here are the results of my implementation of his algorithm. UPDATE: I added the original photo of Marie, as well as the version that was used as input by stippler.

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