Wednesday, January 04, 2006
Motor controller board
Some progress has been made on the RepRap motor controller software and hardware, so it can be stolen for use in the RepStrap too. Although for RepRap it is likely to be fabricated in the future by the RepRap itself, initially it might be a PCB (not yet decided).

However, for Repstrap it needs to be easily fabricated from readily available parts, and although making PCBs isn't very hard it will be simpler and require less equipment if we use stripboard. So with that in mind, I have built motor controllers for Repstrap out of stripboard.

This photo shows the underside of the stripboard for the motor X axis controller after drilling out the unwanted copper points. The Y and Z controllers are essentially the same.

Here, after soldering the components in. There is a heavier duty wire for the ground and 12V to the stepper motor driver.

Full details (and software) will be posted later. They are also available as part of the main RepRap project.

The parts required:

1xPIC16F628A (@NZ$5.24)
1x15V 1W Zener, 1N4744 or similar (@NZ$0.48)
2x1k resistor (@NZ$0.05)
2x4.7k resistor (@NZ$0.05)
1xULN2803A darlington driver (@NZ$4.98)
1x18 pin DIP socket (@NZ$0.54)
1x25 way header pins (@NZ$1.48)
Some wire (perhaps NZ$0.20)
A piece of stripboard around 21x16 in size (perhaps NZ$1.00)
Some solder, etc (maybe NZ$0.05)

Total cost: NZ$14.17

There will be one of these for each of the three motors, along with a controller for the extruder which will be a similar price, and a general common interface module, which will again probably be around the same price. So the electronics are looking at costing approximately NZ$70.

Scrounging parts will bring this down a bit of course.

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