Dust PCB Design
I finished another revision of the Dust protoype schematic.
Changes from the last version include:
- Revised amplfier section. The breadboarded amplifier circuit didn't match the circuit in the physical computing textbook.
- Revised relays. I drew custom parts in the Eagle library for the Omron G6L-1F relays we ordered.
- Renamed parts on schematic so jumpers, transistors, and diodes have matching numbers (eg. Q2, R2, D2, J2). It was difficult to correlate them on the board layout view when their numbers were different.
- Changed motor diode to a SOT-23 package.
- Added landing spots ("Through Hole Pads" in EagleSpeak) for the qprox electrode and the electrode shield.
- Added USB connector
I also finished the first "real" version of the board layout.
It will be a double-sided board with handmade vias in several spots. There was a point yesterday evening when I just couldn't deal with the complexity of routing things on one side of the board only. I asked Rob Faludi to help me figure out how to add "vias" properly. The whole trick with the vias in Eagle is using the Ratsnest command, which redraws the screen and apparently recomputes connections.
Based on advice from a tutorial I found on Instructables, I drew registration marks on the top and bottom of the board layouts so I can align them perfectly before I iron the toner onto my copper clad board.
Next, I printed out the board to see how things would fit.
Next Steps
- Test amplifier circuit on breadboard
- Battery testing -- can we power with multiple watch batteries or do we need a 9-volt?
- Measure the pin spacing on power switch
- Add programming pins for connecting to the FTDI USB port (for upgrading Dust firmware)
- Fix resistor and capacitor package sizes on board design. Resistors are 0805 and there are two types of capacitors: 4x5.5mm and 6.3x8mm
- Etching
- Soldering