Today two sets of PCBs arrived from OSH Park. Firstly a breakout board for Kingbright 14 segment LEDs. These are great for very high brightness text display.
Secondly a small breakout board for the Maestro A2035-H GPS receiver. This is a capable GPS powered by the SiRFStar IV chipset. It supports NMEA or SPI and can update at 5Hz, which makes it an interesting GPS for sport tracking. I plan on using it for tracking go-karts around an outdoor track.
People often ask how I assemble SMD boards, the video below is sped up to 20x and demonstrates the process. It takes a few minutes to dab some solder paste on each pad, then parts are placed using anti-magnetic tweezers. Finally the whole lot is carefully put into a frying pan and heated quickly over a gas hob.
Don’t share the frying pan with anything else - you don’t want to be mixing solder and your sausages!
There is a lot of myth and misconception about whether right angle (90°), chamfered (45°) or curved PCB traces are “better”. One of the often quoted “facts” is that right angles are bad for signal propagation or radiated RF emissions.
I came across a great paper titled “Time and Frequency Domain Analysis for Right Angle Corners on Printed Circuit Board Traces” (PDF link) by Mark I. Montrose which has in-depth analysis and experiments to test this theory out.
I have previously raved about BatchPCB, a low cost prototyping service run by SparkFun out of the USA. However, it seems that you now can’t select shipping to the UK (and perhaps other parts of Europe) and they don’t seem to be doing too much about it.
I emailed a few weeks ago and have received no reply, so all I have to go on is a few posts on their forums which confirm I’m not the only one experiencing the issue.
I have just uploaded the latest version of my Eagle library, containing a bunch of new parts. These include:
Maxim DS1337 RTC RFM12 radio module (with pins) Keystone CR123A battery holder Memsic MXC6202 I2C accelerometer ON Semi CAT6219 500mA LDO regulator Texas Instruments TSL2560 / TSL2561 light-to-digital converter Maxim DS620 Low-Voltage, ±0.5°C Accuracy thermometer The library can be found on this page.
One of the circuit boards I’m developing would benefit from an onboard antenna, so I started hunting for design tips. The following three PDF documents do a great job of explaining the basics:
Freescale “Compact Integrated Antennas“ Kent Smith “Antennas for low power applications“ Ingecom “V / UHF Antenna Design“ I will update the blog once the circuit board is designed and I have managed to test range and effectiveness.
It has been ages since I have updated this site. I have started to document some of the PCBs I have created
The first is an 8x8 LED matrix, with code for some whizzy effects. More information and downloads on this page.
If anybody wants to see the code, I could tidy it up a bit and post with some explanation.
My first bunch of boards arrived back from BatchPCB and I’m really impressed. Great printing for the silkscreen and a really professional looking product. One of the boards I ordered was a breakout board for the SMD PIC 18F2321, the first surface mount board I have tried.