Recent content by Tom2000

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    OT: The Last Good Laptop with a Serial Port?

    About three years ago, after becoming disgusted with the state of USB-to-serial converters*, I bit the bullet and bought a used, refurbished Dell Latitude C610 on eBay for not a lot of bucks. It had a dedicated serial port, so it was good for my Picaxe, PIC, and Arduino work. I spent a few...
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    Codewheel Generator for Optical Encoders

    Howdy, Folks, I've just released a freeware Win XP/Vista program that generates and prints codewheel images that you can use to build homebrew optical encoders. I've included one wheel type that's of particular interest to folks here who are experimenting with robotics, motor positioning and...
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    OT: Codewheel Generator for Homebrew Optical Encoders

    Howdy, Folks, I've just released a freeware Win XP/Vista program that generates and prints codewheel images that you can use to build homebrew optical encoders. I've included one wheel type that's of particular interest to folks here who are experimenting with robotics, motor positioning and...
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    Writing Maintainable Picaxe Code

    The Problem with Picaxe BASIC When writing a large microcontroller program, it's very important that you write your code as clearly as possible. You should be able to figure out, without a great deal of effort, exactly what it's supposed to do, and precisely how it's supposed to do it. If...
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    Does hspi work on the 28X1 A.0?

    I'm designing a system to control an Analog Devices AD9851 DDS chip from a 28X1 A.0. The 9851 requires 5 bytes transmitted serially and sequentially, clocked by the rising edge of the clock pulse. It doesn't require a chip select, and it sends no data to the 28X1. (I need two other leads...
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    150KHz-30MHzReceiver Design, Revisited

    On 15 May, 2007, kranenborg opened a thread discussing the design of a wideband superhet receiver. His goal is (I'm going to address the following comments directly to Jurjen.) Jurjen, I've been down that road a number of times over the years, to varying degrees. In every case, I've found...
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    OT: Boston Dynamics "Big Dog"

    Sorry in advance for the off-topic post. This isn't a Picaxe project (or at least I don't think it is...) But it's so impressive that I just had to share. "David L. Jones" posted, in sci.electronics.design, this Youtube link of a video showing the performance of Boston Dynamics' "Big Dog"...
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    OT: PCA9555 16-bit I2C I/O Expander

    When folks need more I/O, the most common solution seems to be the 74xx595 shift register. For applications that need to drive a lot of LEDs, the MAX7219 is often the chip of choice. I might have found something better - the NXP (and TI) PCA9555 I/O expander. This chip provides 16...
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    OT: Free Calculus eBook

    I've been brushing up on my calc and diff eq. I found a superb free eBook: Calculus by MIT Prof. Gilbert Strang. Strang presents his information by first stressing and clearly explaining fundamental concepts, then, if possible, relating said concepts to real-world situations. He carefully...
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    OT: L4941: LDO 7805 Replacement?

    Data Sheet While mousing around on the Mouser site, I stumbled across this LDO 5 volt regulator that, in a 3-lead TO220 package, appears to be a pin-compatible 7805 replacement,. It has less than 1/2 volt dropout vs approx 2 volts for the 7805. It doesn't seem to require the large output...
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    DS1302 -- 08M Test Routine

    Below is a little test routine that I wrote for someone having problems with the DS1302 real time clock chip I specified for another project. He has an 08M on hand, so we thought if he could get the DS1302 running on the 08M, independently of the other processor, it would tell us where to look...
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    OT: Bargain eBay Oscilloscopes

    I bought a cheap scope on eBay five or six years ago. At that time, the Tektronix 2235 (which I bought) was "THE" bargain scope. There were a bunch of them, all going for very good prices. 100 MHz, dual channel. Built like a tank. That scope has been a real workhorse for me. It's been a...
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    18X/8 MHz Loop and ADC Timing

    I was curious about loop termination test time and someone in here was curious about ADC timing recently. I set up an 18X, running at 8 MHz, and measured loop timing under different conditons using my oscilloscope. In each loop, I included a toggle 0 instruction. I connected my 'scope to Out0...
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    Ultrasonic Transducer Ideas?

    Just on a whim, I picked up a couple of ultrasonic transducers recently. They're supposed to operate near 24 kHz, which is well within the range of a Picaxe's PWM output. I don't play with robotics and have no real need for a rangefinder. Don't know what I'd do with one if I built it. I've...
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    OT: "Found" Project Boxes

    Someone just gave me an old 3 1/2 inch plastic floppy disk box. He asked me if I had any use for it and, just as I was about to say that I haven't used floppies in years and I couldn't use it, I realized that it was the perfect size to house a small project. I said "thank you!" If you have...
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