Sparkfun Dumpster Dive 2016 Unboxing

The day has finally arrived! Sparkfun had a dumpster dive last week, and I managed to get a 0.5lb box. I had the big box in my cart too, but it was out of stock before I could get to checkout. With some knolling: And now for the list of goodies: FTDI 5V cable 9V battery holder with barrel jack 56 and 200K resistors 10K pot with wires 4 matching pot knobs VGA connector Lilypad Arduino v1.1 (works so far) 5pk of lilypad green LEDs. 12pk of some 12A 60V P-Channel MOSFETs (NTD2955) 3V coin cell some kind of snapping connectors for fabric (Female half) A slightly mangled breadboard A base for a breadboard and some Dev board. some screws (hopefully M3 but might be #4-40) some Brass standoffs (hopefully M3 but might be #4-40) some small female headers (mostly 1×4) An enclosure with some milled holes (happens to be […]

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LED grid Part 2 – First hardware tests

This is part 2 of the led grid project, a joint project of engunneer.com and ericagunn.com. In the last post, the boards had just arrived, and the rest of the parts were on order. A few days later, everything was here! Because resistors are so cheap when you get 100 or 500, it was worth getting a few extra values to allow for testing the IR receivers. Just before assembly, I realized why DirtyPCBs are so cheap, and why they do electrical tests on all boards: Yes, that’s blue sharpie on top of a hand repaired trace. About 30% of the boards had some kind of repair like this. I soldered one board up and started testing. Getting the color LEDs working wasn’t a big deal, but I had problems with the IR power supply (which is also duplicated for the shift registers). It just wasn’t regulating voltage and had […]

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Led grid part 1 – Design Process

This is a copy of a guest post I wrote for my wife’s blog, about building an LED Grid for our collaborative design project The hardware for the LED grid project consists of two major elements: The LED lights, and the IR touch system. The first idea for the board had the main LEDs spaced out in a 10mm grid. I prototyped this on some surface mount prototyping board to see if I could fit everything needed into the space available. It was a bit of a tight fit, and the nature of how I made it makes it not very pretty. Because the LED cells were so close together, I had to alternate the IR touch transmitters and receivers in each column to keep them from interfering with each other. This was enough to prove out the concept and get initial values for the resistors for the touch system. […]

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Office organization

There was a discussion on the askelectronics subreddit about part storage, which reminded me that I’ve been meaning to post about the latest office arrangement. For the video tour, see this post. Since the main question is about components, I’ll start there. Since the organization has grown over a decade or so, there is some duplication and some things that could be grouped better, which is an ongoing process. This is the main electronics workbench in my office: From top row, left to bottom row right: Grey bins – the oldest bins. Contains US machine screws, wood screws, nails, etc. Teal bins – until recently this was metric hardware and rivets, but most of that has moved to primary storage (covered below) – now mostly empty Partitioned containers. These are $10 from the container store. There are 5 in use here and 3 more emptys in primary storage. This is […]

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Meet Sparky

Quick project last night to upgrade a skull with flickering red eyes. Steph had properly themed bouncy balls to go in the eye sockets.  I added some red LEDs and an ATTiny13. I borrowed two different code snippets to make it blink with a nicer look. Hackaday Link for project 1 (used the LCG formula) Zenlogic’s PWM code (modified to use only two outputs) Click to view video.

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New electronics for the makerbot part 2

Here is my makerbot electronics as of Friday. Including the relay board, there are 7 boards involved in running the bot. I finished soldering the proto board to connect my Pro Mega to the Quadstep Friday night. I got everything torn off and installed my new board stack in place. Still some work to do for making it look nice, but it’s already a big improvement. Moving on to the software side, I had a heck of a time getting anything to load from the Arduino environment. After nearly 8 hours of debugging and finally loading the basic blink program via the AVR Isp port (which involved teaching the Arduino environment that my pololu AVR programmer is like an stk500v2), I discovered what was happening. It was toggling the blink Led every 2 seconds instead of 1! I triple checked the fuse settings against various AVR calculators and they were […]

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New Oscilliscope Part 3 – Screen Capture

With the TDS544A up and running, I decided to take a crack at getting data off of it. The scope has a floppy drive (but my laptop doesn’t), a GPIB port, and a printer card with both parallel and serial interfaces. The hardcopy menu has around 18 options for filetypes, and is capable of sending the screenshot to any of the ports or the floppy drive. Of the options available, I decided to try sending a windows BMP file over the serial port. I used a F-F null modem cable and a USB to Serial converter. On the program side, I started with this autohotkey script which spews data from your serial port into notepad. With a little bit of munging (removing anything to do with sending data, and removing some of the ASCII conversion logic), I was able to get and write BMP files. A full 640×480 color bitmap […]

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New Oscilliscope Part 2 – Repair

Continuing work on the TDS544A, I got all of the electrolytic capacitors off, and cleaned the board with simple green and alcohol. I took careful notes about what value of capacitor went where, and how all of the cables are hooked up internally. I also noted any switch settings I could find. The Digikey order of capacitors and a brand new ultra fine tip for my iron arrived.Here we are mid process on getting all the capacitors back on. It turns out I did not order enough of the 33µF capacitors, so I ended up substituting the 10µF capacitors in some places on the logic board, and on the front panel. The Acquisition board got all the proper values, since it might be important for the RAM and other major signal processing elements. On the logic board, I replaced about half of the capacitors on the power rails with the […]

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New Oscilliscope Part 1 – Disassembly

We were cleaning out the lab at work, and throwing out older lab equipment, and I scored a Tektronix TDS 544A. The sticker indicated it needed to be repaired and calibrated, and it just wasn’t going to be worth it, so they were tossing it. I scooped it up, and I’ll have a few blog posts about the repair process. First, the good – It’s a 4 channel 500MHz digitizing scope with a color CRT screen. It beats the heck out of my older TEK T935A, which is an analog 2CH 35MHz scope. I think the biggest win is the ability to stop the scope and look at a trace, as well as much more powerful triggering options. Powering it on, it has a few faults in the self diagnostics, and research online shows that the main problem with scopes from this era are the aluminum electrolytic capacitors on the main […]

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