While browsing dangerousprototypes.com I saw an interesting little gadget by Mark Frejek at www.mikrocontroller.net. Mark had made a transistor and component identifier using an AVR ATMEGA8, a few resistors and a 16x2 LCD. Always wanting one of those expensive Atlas testers I was intrigued.
I saw a few examples of people building the circuit on the net and the operation of the gadget seemed to be really well done. The software seemed very polished and comparable to the Atlas devices that I've only seen in person at trade shows. Also, having all the required parts in my bins and the long standing niggle in the back of my brain telling me to try and find a use for that ATMEGA8 DIP uC I've had floating around for a while, it was almost a match made in heaven.
My friend Alan Yates is currently working through all manner or particle detectors. His latest one is a Gas Electron Multiplier. It's basically a very two very thin plates with many tiny holes that electrons can go through triggering an electron avalanche between the two highly charged plates.
He was going to try using a piece of veroboard, when I said I'd make him something on the CNC.
Thanks to Tyson I have a good set of solid carbide PCB drills down to 0.25mm. Alan was only after 0.3mm and 0.5mm spacing so I easily managed that on the Widgitmaster machine.
Here is a small update on a project I'm working on for a client.
I've subsequently dropped the split quadrature encoder set up and added another shaft encoder on the actual lead-screw. So now I can actually use a stepper or a servo and I close the control loop using my own shaft encoder. I've still got to put up with the non-realtime kernel but it's a lot better and good enough for what I need.
What got me started on wanting to increase my RF knowledge was this article by Dave Richards. I was originally looking for interesting ways to make project cases and happened to find his glorious "double-sided PCB case" technique. The technique has been around for a while, but the circuit he built in it was just so pretty I had to have a go. His little story about using shortwave radio as a kid piqued my interests enough to actually sit down and build one.
So here are some short videos of my attempts at the WBR receiver originally designed by N1BYT.
Once again *many* thanks to the guys on Twitter for their assistance. It turned out I had a bunch of dodgy MPF102 j-fet transistors which hampered my initial testing.
I decided recently that RF was a field I had very little practical knowledge of. I know the basics, the methods and the general ideas, but I've never actually put together a circuit other than a pre-purchased kit.
Thanks Alan Yates and the guys on twitter I set out to be a simple RF oscillator. I also really wanted to build something using the "manhattan" construction style.
You can see above I'm using the CRO probe to inductively couple with the tank coil.
I've still got the circuit bouncing around my desk, I'm going to attempt to build a Direct Conversion receiver with it when I have some time.
Been playing with some code to convert images to GCode. Here is a test sample. Not bad I reckon. From 3 metres away it looks like a black and white photo. :)
Further work on my "Alarm Clock" I wanted an alarm function that could play WAV files from an SD card. This will allow tailored alarms for each alarm to be played.
I needed to output some debugging from a micro controller, usually this is easy. Just plug in a MAX232 and connect up a USB to Serial cable and you're away. But in this case I was using 3.3v making the MAX232 useless. I didn't have any MAX3232's in my boxes and I didn't want to fiddle around with resistors etc to make a rudimentary level converter. I needed something, and I knew it was something I would use time and time again in the future so I set out to make a LVTTL USB to Serial cable.
Looking at the various USB to Serial cables I had, I came across one that I could clearly see had a FT232BM. Looking up the data sheet for the FT232BM I found in the app notes that this chip can be configured to be 5V bus powered, 5V self-powered, 5V bus powered with 3.3V I/O and 5V self-powered with 3.3V I/O.
I've been working on a small project of late that utilises an ATMega32 and plays WAV files from a SD card. I'm using ELM Chan's Petit FatFS to do the FAT translation, but I was having issues with the SD card configuration and communication. Getting frustrated I started using my S3E development board as a SUMP Logic Analyzer for a while until I splurged and bought an Openbench Logic Sniffer which is based on the SUMP LA.
It cost me $46 AUD with free shipping from SeeedStudio. The "free" shipping took about 3 weeks to get from Hong Kong to Sydney Australia so I was less than impressed with that, but I'm more than impressed by the little board.
After setting up "the alternate" SUMP client and connecting up my SD card logic lines I soon had a sample of where my problems were. Also the SPI decoding build into the client was a joy to use and very very handy. The S3E version does have the advantage of the larger capture buffer (512K vs 4K) but using 115200bps serial as opposed to the 1Mbps of the OLS's USB connection this limitation is soon forgotten.
Having this board on my bench for a week or so, I was starting to worry about damage from things being dropped on the board while in use. So I set out to make a Perspex case similar to my Bus Pirate case. And here is the result...
