Archive for month: January, 2012

Interesting “feature” re: _delay_ms in avr-libc

January 31, 2012 | Arduino, Atmel AVR, Microcontrollers | By: Mark VandeWettering

A couple of my projects have used the tiniest of the Atmel ATtiny chips: the ATtiny13. I have written one or two programs in assembler for these chips, but I prefer to work with avr-gcc whenever possible. What’s amazing is that you actually can use a sophisticated C compiler to generate code for such a […]

ksim 8080 simulator released

January 31, 2012 | Emulation | By: Mark VandeWettering

Fellow hacker Eric Smith has released the code for an 8080 simulator. I spent a few hours hacking my own 8080 emulator a few months ago, and at least got it to run Tiny BASIC, but I was never quite successful in getting it to boot CP/M. Among some of the problems were that I […]

A $.33 MAX232CPE, or a $0.01 2N3904?

January 28, 2012 | Arduino, electronics | By: Mark VandeWettering

In response to my previous post, @xek replied: @brainwagon has anyone suggested the stupid bjt inverting “buffer” trick? 1/28/2012 7:04 pm via TweetCaster for AndroidReplyRetweetFavorite @xek Josh Myer Well, the fact is I had heard of doing that. It’s not really hard to rig something that will convert the RS232 level from the GPS into […]

Tinkering with an old GPS receiver…

January 28, 2012 | Amateur Radio, Arduino | By: Mark VandeWettering

I used to be an electrical engineer like you, then I took an arrow in the knee. (If you don’t get this, google for “arrow in the knee”, and guess what Xbox game I spent the morning and afternoon playing instead of working on something cool.) I’ve had a number of projects that could benefit […]

AVR-based FM-transmitter

January 26, 2012 | Atmel AVR, Microcontrollers | By: Mark VandeWettering

This is a very cute hack that does something which I thought was impossible: an implementation of an FM transmitter that has exactly two components: a battery and an ATtiny45 microcontroller. It’s brilliantly obtuse and cool: Sprites mods – AVR-based FM-transmitter – Intro, theory The basic idea is to trick the internal oscillator of the […]

Unequal Resistor R-2R Ladder Optimizer

January 26, 2012 | electronics | By: Mark VandeWettering

I was reading up on resistor ladder DAC circuits on Wikipedia, and came across the Unequal Resistor R-2R Ladder Optimizer. It’s very neat! You can enter the number of bits you need, and the values of the pile of resistors that you have measured from your bench, and it will produce an optimized design using […]

New 6502 processor at

January 26, 2012 | electronics | By: Mark VandeWettering

Dave Jones (@eevblog) tweeted: The 6502 is back: 1/26/2012 6:40 am via TweetDeckReplyRetweetFavorite @eevblog Dave Jones And indeed, he’s right! WDC (the Western Design Center) has made a new version of the 6502 available at It’s a 40 pin DIP package, listed at $6.95 in quantity one, and can be clocked up to […]

Creating source material for Narrow Band TV…

January 24, 2012 | Narrow Band Television | By: Mark VandeWettering

I’ve often thought that creating a replica of an early Baird mechanical television, or televisor would be a fun project. But when starting, you immediately run into the problem of how to generate material for them. The Narrow Band Television Association standard format specifies 32 line format at 12.5 frames per second (400 lines per […]

High Frequency Precision Sine Wave Synthesis for the Arduino by Adrian Freed

January 23, 2012 | Arduino | By: Mark VandeWettering

While researching something completely different, I found Adrian Freed’s very cool page with code to generate high quality sine waves using PWM on the Arduino. This code could serve as an audio frequency signal generator, or as the basis of a computer music project. It also demonstrates some non-trivial Arduino wizardry in dealing with PWM […]

New addition to the brainwagon lab: a Rigol DS1102E

January 22, 2012 | electronics | By: Mark VandeWettering

This week, I splurged and bought myself a new piece of test equipment: a Rigol DS1102E 100Mhz oscilloscope, and compared to my old 25Mhz Philips (which was indeed a great buy at only $20) it’s very, very cool. Among the most neat features that I’ve started to use is the ability to do screen and […]

An Arduino powered IBM PS/2 Morse Keyboard

January 21, 2012 | Amateur Radio, Arduino | By: Mark VandeWettering

I’ve been trying to do a bit more Arduino programming and interfacing lately. Nothing too difficult, but just trying to expand my junkbox and my skills so that I can quickly prototype new ideas and expand the kind of projects that I can tackle in the limited time that I seem to have for playing […]

Interesting discovery regarding a junkbox piezo element…

January 21, 2012 | electronics | By: Mark VandeWettering

I was tinkering with a small electronics project (article and video to come) and needed a sound output. Digging around in my junkbox, I found one of these piezo speakers, and decided to use it, driving it with a square wave from my Arduino: Piezo Element 1500-3000Hz – My initial test was supposed to […]

On Relay Computers…

January 20, 2012 | electronics, Retrocomputing | By: Mark VandeWettering

I share an interest in old computing technology with several of my friends and readers. An interesting sub-topic within this vast area is the world of computers based upon relays. In the last couple of days, I found cool links to two different relay based computing projects, so I thought I’d pass them along. First […]

Nice new breadboard and power supply from

January 18, 2012 | Arduino, electronics | By: Mark VandeWettering

This is just a plug for a cute little pair of gadgets that I got the other day.. If you are like me and use solderless breadboards to experiment with stuff on the Arduino, you end up with the Arduino and the breadboard connected by a hodge podge of wires, and if you accidently tug […]

A phrase I don’t like: “Dumbing down.”

January 14, 2012 | Rants and Raves | By: Mark VandeWettering

We’ve all heard it (and most of us have said it): “X is just a dumbed down for the masses.” Heck, I came dangerously close to saying it myself in today’s earlier rant. But I didn’t say it, and I try not to, because I think it’s not really very useful. First of all, if […]