Version 6 (modified by roh, 14 years ago) (diff)



this repstrap is a bit different: it doesnt use any of the reprap default electronics or sourcecode on a microcontroller

the gcode is generated like usual via skeinforge or similar tools but emc2 and some shell and python components take control of parsing it and doing the magic.

the dc-motor as visible in the pictures for the classic darwin-style extruder we currently use is driven by a dc-motor driver based on this:

also in the same box are 2 tip122 transistors which switch gnd for 2 supplies in open collector mode.

the whole thing is deadlocked with and-gates (inline in the 'step' and the pwm lines for the transistors) with the other 4 inputs of the and-gates driven from a 'charge-pump' <add schem>

the chargepump gets a 'rectangular ac signal' on one input. if its missing the output goes low. if it hangs high, the same. see it as an electronic dead-man switch driven by emc2

its based on some caps, diodes, more caps and 2 or 3 transistors. i'll add a schematic soon.

for some pics of our extruder head see blogposts about reprap

uses for the arduino code i use for measuring temperature (means the voltage)

configs: (for now, will move that somewhere here)


  • does one really need/want a 80mm fan to force-cool the object?
  • build stepper-direct-drive and compare it against our geared worm-drive
  • try geared motor as direct drive.
  • fix heater-pid-loop Dgain
  • clean up code
  • Documentation / pictures / howto


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