Here they are. Finally. Field-tested, known good goodies.
Gerber Files (zipped)
Eagle Files (Authored in Eagle 5.10 Professional)
T3 Parts List (text file)
- Processor is a PIC 18F2610. It has many pin-compatible brethren.
- Top of the schematic contains a neat RS-485 receive section which is both optically and galvanically isolated from the rest of the world. This conforms neatly to the official USITT spec, and this particular corner of the schematic has been field-proven by many hundreds of our other customers, over several years.
- There’s a single LED for power, plus a second LED for status / user feedback.
- This PIC contains EUSART and SPI peripherals on (conveniently) separate pins. To drive 4 different string outputs, we use a flock of ‘AND’ gates to select and route the data to its proper destination.
- Expected power source is 5V DC via a switching supply, rated at 3A per 42 nodes driven. A fully loaded card requires about 12A.
- There’s no polarity protection included on this board. Caveat emptor!
- Most parts are SMD. Chips are SOIC, discretes are 0805. Easy easy to hand solder.
I have 7 remaining bare PCBs based on this design. An additional 15 are en route to mrpackethead (.nz) for distribution. $10 each or 5 / $45. If you want some, email ‘john AT response-box.com’ with the subject ‘Open Source PCB’
I do not plan to re-run these boards once current supply is depleted.
Source code is coming soon. Check back!