Step 5: Electronics
I started soldering the steppers. I used a ribbon cable to connect the steppers and solder them to the existing connections from the DVD boards. On the other end I solder a four pin header so that it could be used with a breadboard. The same thing goes for the Easydriver, solder pin headers and use them with the breadboard. Ribbon cable can be found in abundance around old computer shops and service centers. All those old disk drive cables can be of good use.
In the schematics I have added a relay for use with a fan. This can come in handy as the engraving produces some smoke.
The Easydriver have two pins called MS1 and MS2, these sets the step sequence. Tie them both to the five volt output from the Easydriver. This sets the step sequence to micro stepping . The four pins from the stepper connect to the motor output. All steppers I have found have all had the same pinout on the small connecting PCB. Connect the pins in the same order to the Easydriver as on the connecting PCB. The control pins (step, dir, gnd) goes to the Arduino. Besides this the Easydriver needs motor power connected. I use a twelve volt wall wart that drives the motors, fan and Arduino. There is a potentiometer that controls the power to the motors, I just set this to the lowest setting and turn it up a tad if the steppers don't have enough force. I don't know the rating on the steppers, if they gets to hot you’re driving them to hard.
The fan just needs to be connected to the fan output. A small computer fan works well, just connect the positive and negative leads to the correct output.
The laser driver is an LM317 based circuit with no specials. This will work fine but it is far from optimal. I am driving the laser diode far too hard at about 300mA and if you do that you can’t expect a very long life for the diode. The best solution would be to find a stronger laser and better driver but to keep to the spirit of things I wanted to use the laser from the DVDR itself. Laser on/off is controlled by the same relay as the fan.
If you want to simplify you could skip the whole laser driver and use a readymade driver. Then all you would have to do would be to connect the power to the fan relay. Of course this would probably be a little bit more expensive.
The whole thing evolved into a new Arduino shield, the Laser Shield. I have included the schematic and board layout in Eagle format . Creating a circuit board is a bit out of the scope for this instructable, but there are lots of really good guides here on Instructables.
If you want to make your own layout with Easydrivers I have made a Eagle library with the driver, it can be downloaded here .
In the schematics I have added a relay for use with a fan. This can come in handy as the engraving produces some smoke.
The Easydriver have two pins called MS1 and MS2, these sets the step sequence. Tie them both to the five volt output from the Easydriver. This sets the step sequence to micro stepping . The four pins from the stepper connect to the motor output. All steppers I have found have all had the same pinout on the small connecting PCB. Connect the pins in the same order to the Easydriver as on the connecting PCB. The control pins (step, dir, gnd) goes to the Arduino. Besides this the Easydriver needs motor power connected. I use a twelve volt wall wart that drives the motors, fan and Arduino. There is a potentiometer that controls the power to the motors, I just set this to the lowest setting and turn it up a tad if the steppers don't have enough force. I don't know the rating on the steppers, if they gets to hot you’re driving them to hard.
The fan just needs to be connected to the fan output. A small computer fan works well, just connect the positive and negative leads to the correct output.
The laser driver is an LM317 based circuit with no specials. This will work fine but it is far from optimal. I am driving the laser diode far too hard at about 300mA and if you do that you can’t expect a very long life for the diode. The best solution would be to find a stronger laser and better driver but to keep to the spirit of things I wanted to use the laser from the DVDR itself. Laser on/off is controlled by the same relay as the fan.
If you want to simplify you could skip the whole laser driver and use a readymade driver. Then all you would have to do would be to connect the power to the fan relay. Of course this would probably be a little bit more expensive.
The whole thing evolved into a new Arduino shield, the Laser Shield. I have included the schematic and board layout in Eagle format . Creating a circuit board is a bit out of the scope for this instructable, but there are lots of really good guides here on Instructables.
If you want to make your own layout with Easydrivers I have made a Eagle library with the driver, it can be downloaded here .
Lasershield.zip73 KB
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Great tutorial and awesome idea !
Laser driver circuit:
C1 0,1uF
C2 47uF 25v electrolytic
D2 SA15A
IC1 LM317
R1 3,9 ohm
R3 51 ohm
R4 1 K ohm
R6 500 ohm TRIM POTENTIOMETER
Relay circuit for fan and laser:
D1 1N4148
R2 2,2 K ohm
T1 2N2222
VR05R051 RR1A (306-1019-ND at Digikey should work.)
U1 EASYDRIVER
U2 EASYDRIVER
U4 ARDUINO
i have troubles with the relay circuit, at the half of the work, the laser does not cut mark all the displacements, what can i do? what other relay can I use?
Do you have to solder the wires to the stepper using the PCB strip? Can't you just solder them directly onto the pins on the motor? Asking because this may be a little beyond my skill level.
http://cgi.ebay.com/Constant-current-laser-diode-driver-80-500mA-w-TTL-/380348154175?pt=LH_DefaultDomain_0&hash=item588e84413f#ht_754wt_1141
c2
vcc
ground
mod
r9
r10
At one end of the board the pads labeled VCC and GND connect to a 5 volt source. For your project this could be a seperate power supply, a 5V regulator (Like a LM7805) running off your 9 to 12V supply, or you may be able to tap this off of your Arduino board (if it has enough current capibility). The current requirements from the 5V supply are in the 200-300mA range (for DVD diodes). Be sure that all the ground (GND) connections for the Arduino board, the stepper motor driver boards, and the power supplies are connected together.
The MOD pad (on the back of the board) connects to D12 on the Arduino board to control the laser on-off.
At the other end of the board. The pad in the center (next to the C2 label) is the "+" output (to the laser anode). On the other side of the board (next to the R10 label) is the "-" output (to the laser cathode).
Thanks!
Try this link.
If you saved the original ribbon cable with 4 conductors, most of the time I saw it wired in sequence: A(positive) A(negative) B(positive) B(negative) where positive and negative are actually just a matter of convention - if moves in a wrong direction, swap them. If it moves back and forth instead of continuous move in one direction, swap A and B.
This only applies to desktop drives I've opened so far. Laptop drives have these winding contacts all over the place because most of the time there are extra signals hitching a ride on that ribbon cable, so they just stick the winding where it's convenient due to layout. On a laptop stepper you'll just have to use a multimeter as Groover explained.
So, once you've identified the windings, you have 4 choices
swap polarities on A but not on B
swap polarities on B but not on A
swap polarities on A and B
swap A and B
That would be the two windings in the stepper. And if the stepper moves in mysterious ways try changing place on one winding.
I'll have to give you a better answer as soon as I get home and can have a look at the board layout.
The interlock is supposed to be a safety feature. You can put a jumper there and ignore it or use it as a safety switch. I think a hardware switch is a safer option that to just trust software. For example if the software would malfunction for some reason while the laser is on it could be a good idea to be able to shut it down without having to pull out the power and USB. Of course this was never implemented in my hardware design even if it would be a good idea.