Alan numitron clock
SNES Pi Webserver
USB Volume/USB toys
SNES Arcade cabinet
Game boy projects
Home Presence Detector
Rand Nerd Tut
Carnet du maker (fr)
ATmel blog (defunct)
Epson PM-A700 I scavenged the print head rail and motor (looks good and strong DC motor and position combo), the scanner motor and rail (Stepper motor but look not quite strong though), the paper moving motor (DC motor) and the alim (spits %2040v with no load ... need to check that)
Mabuchi RS-445PA (14233)). The position can be checked using a transparent stripped band that runs along the motor belt and a small circuit that reads the "position" or more precisely the movements (counts the dark bars). The circuit has a VCC & GND input and 2 bipolar output.
The 2 output wires return high or low when the head moves and the stripes goes in front of the reader chip. But easier is that each wire is in fact TTL level. It is a positional code type "Simple incremental encoder" http://www.electronics-tutorials.ws/io/io_2.html
The setup is that when the head moves the position reader generate state change each time it moves. Just wire the position head to a external interrupt of the Arduino and "count" the plus or minus on each state change of the pin depending of which direction you go. The main code while moving moves and check the "position counter" and stops when you're arrived. Not perfect, but okay for a beta version. FYI I use just one of the two position counter which is sufficient for now.
http://www.ebay.com/itm/110953019447) but any H-Bridge configuration should be ok. I finally decyphered what was written on the motor, it's a Mabuchi RS-445PA (14233) that works in the 12-40v range (!) (Specs are http://www.mabuchi-motor.co.jp/cgi-bin/catalog/e_catalog.cgi?CAT_ID=rs_445papd) which is "ok" with the H-Bridge module that works on the 5-35V (specs says 46V but...). I will just need to provide the 5v since the maker advise to not use the on-board 7805 if fed more than 12v.
Setup is the following : reuse the 40v alim from the printer, reduce it around 35v with a serie of diodes, use a DC-DC converter to make it 5v to feed the logic (arduino) and 35v to feed the motor.
In case I change that later, the ebay magic keyworks to get the part to put on top of the stepper to drive the belt are pulley teeth stepper (just a reminder, I spent 1 h searching how the rest of the world call these things).
Color code of the connector is : coil1 [orange-brown] and coil2 [black-yellow].
Coils read 40 ohm, sheet says 25 ohm, one guy says 8ohm ... well. It works with 5v (not much torque) and 12v (feels more like it boy!) but at 12v the motor itself and driver get hot quickly. Can still touch it though, we're clearly less than 50C but maybe I'll put a current limiting resistor ? Will depend on real life result.
For memory, here's how the wiring works with the sample program bipolar_stepper.ino :
Wiring for the bipolar stepper. Motor VCC is 5v (see more below).
The stepper motor does 3.75 degrees per step means 96 steps for 1 full turn. I noticed however that it was not enough to make one turn of the final wheel (there's 2 intermediate wheels). In fact experimentally I found that there's a reduction factor of 2/3 means you need 96 * 1.5 = 144 steps to do one turn with the wheel that drives the rubber band.
Notabene : as per experiment, one needs 6 steps to make the bed move 1mm.
The both skates rely on small metal ball encased in blue plastic pyramids and the "track" they follow is carefully greased with cheap lithium grease.
The first skate installed : along the blue axis the skates forbid tilt on the green and red axis
The blue pyramid are those cheap metal ball mounted in plastic to move your small furnitures around
Setup : 40v printer power supply (green), transformer to 5v/12v/35v (purple), 2 motor driver (in cyan), an Arduino with a vanilla shield and wire-orgy (in red) and the stopper position of the bed (in yellow)
The first star drawn with a pen thanks to a quick Bresenham algo and after tuning of the head PWM ... not bad as a start
ATtiny2313 for the display and status led control. Communication between the main Arduino and the display module is done over I2C. This removes the burden of unnecesary code on the Arduino main controller side, and was a good occasion to play with other micro-controllers and I2C as slave.
Arduino and a laser.
On Google SVN http://code.google.com/p/alanarduinotools/source/browse/#svn%2Ftrunk%2FLaserCutterController
For the LCD module see the project http://code.google.com/p/alanarduinotools/source/browse/trunk/#trunk%2FAttiny2313 ⇒ LaserCutterDisplayController project.
Some doc :
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