This is a single-sided version of the makerbot stepper driver board v2.3
thingiverse.com/thing:393

I tweaked the board to make it easier to etch and make at home. The vias are not underneath components, simple wire links can replace the tracks on one side of the board, and the track sizes tweaked a bit.
It can still be improved.

This is a breakout board for an arduino that boosts the 5v signal from the arduino output to a high-power 12v, suitable for running RepRap heaters, fans, heated beds, etc.
The IDC will plug into my Arduino Mega Shield ( thingiverse.com/thing:3308 ) and the power socket is designed to accept standard PC disk drive power plugs.

The signal from the arduino is amplified using a MOSFET - I used FDB8880 ( uk.farnell.com/jsp/search/productdetail.jsp?SKU=1228327 ) at 60p each, which will handle 54A - which is way more current than I expect to ever need, or can be supplied from a single PC power supply.
There are also 8 separate outputs on the board - populate as many as you need. I'm a big believer in multiple redundancy.

It's a nice simple board and it is a good introduction to SMD soldering - each output is separate, so you can mess up one circuit and still use the other 7. I'm also not the most skilled or tidiest maker, and I managed to make it work :-).

I've been working for a couple of weeks on a RepRap Arduino Mega shield. I've got a mix of early generation 2 electronics, a few home-made single sided generation 3 stepper boards, and old arduino with a screw-terminal shield and a brand-new arduino mega.

I designed myself a version of an arduino mega shield to connect the gen3 stepper boards using the 10-pin IDC cables, and it might be useful for anyone transitioning between generations of electronics. Features:

Single-sided for PCB for easier home-made boards
5 stepper driver headers - x,y,z,a,b - should match existing gen3 electronics.
(future-proof?) UI interface header that *should* match gen4 electronics.
Heater 10-pin IDC (to plug in MOSFET driver board later) - should be able to drive a reprap setup with 1 or 2 extruders/ heated bed without an additional extruder board.
I2c header as per standard boards
Optional extra 3-pin headers for digital inout and analog in : +5v, GND, and data pin. This makes it easy to add temperature sensors, kill switches, extra limit switches, etc (I'm only using the min endstops).


You can treat this as more of a prototyping board, and solder as many headers/pins as you need: I bought a dozen 50-pin headers, so I filled mine up. I'm only expecting to use one or two of the analog inputs as temperature sensors for now.

NOTE that the +5v/Gnd/Signal headers for the digital and analog pins are directly connected to the internal arduino 5V supply. DO NOT run anything major off these headers. I was only planning to add simple data switches (digital input from high/low), simple thermistor circuits (Analog input) and potentially a small servo (9g micro servo) off these I/O pins - so I didn't pay much attention to them. If you are running any further circuits, use a separate power supply! (all RepRap boards have separate 12v PSU headers anyway).