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Arduino Camera Focus - (totally new to electronics)
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Arduino Camera Focus - (totally new to electronics)

by efrain_melendez on Sat Sep 11, 2010 11:54 pm

Hello,

I am currently a film student - total newbie to electronics. I have some basic questions regarding electronics and an Arduino project I found.

I am building a 3D camera in a beam splitter setup (basically syncing two cameras and aligning them using a 50/50 mirror). For focusing the lens I need a device that controls the two cameras simultaneously. I started with an arduino, rc servos, and the basic servo code from the arduino example code. It worked great! But, the servos have their own issues and after a lot of testing realized they are not the best solution. On to steppers!

I found an amazing open source Digital Follow Focus project using an arduino, steppers, and a wii nunchuck (video here: http://www.youtube.com/watch?v=rFQzYxlfYl4&feature=player_embedded - project website here: http://weblogs.thinktecture.com/digitalfollowfocus/). The code is open source and incredibly awesome. I am a total beginner and don't know much about code, components, or how to read schematics. But hey, so far it's been a pretty fun learning experience.

The author suggests building an additional component for the steppers using a Bridge Driver. I am reading the schematics and trying to understand the components that best utilize the Bridge Driver. (Check out page 17 of the driver's data sheet http://docs-europe.origin.electrocomponents.com/webdocs/0daf/0900766b80dafb99.pdf). I will be soldering this together on an Adafruit Protoshield.

1.) The data sheet suggests an operating supply voltage from 8 to 52 V. Does this mean that I can literally power up the driver with anything in that range? I am thinking about rigging up two DV Camcorder Li-ion rechargeable batteries rated at 7.2 V with these battery plates http://www.varizoom.com/products/batteries/s7000FPJ.html. By connecting the negative wire to positive wire on the battery plates, would I get a total of 14.4 volts? Could this potentially drive two steppers?

2.) The schematics indicate a few "Signal Grounds." Does mean that I should connect all the ground icons to the negative charge on the battery?

3.) Servos have 3 wires (positive, negative, digital). On the steppers that I ordered (http://www.sparkfun.com/commerce/product_info.php?products_id=9238) there are four wires. How do these wires control the stepper? Is it similar to a servo? The schematics for the Bridge Driver suggest connecting the stepper to the outputs labeled as "Load A/ Load B." Does this mean that I can connect two separate steppers? Or does this indicate the pins I need to connect to the four wires on the stepper?

If I connect two steppers by splicing the same outputs of the Bridge Driver will the steppers stay "in sync" for camera focus?

Thank you so much for your answers!
efrain_melendez
 
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Joined: Sat Sep 11, 2010 11:29 pm

Re: Arduino Camera Focus - (totally new to electronics)

by adafruit_support_bill on Sun Sep 12, 2010 7:08 am

1) You will need to match your supply voltage and your steppers. For intermittant operation, anything rated in the 12-16 volt range should be fine with a 14.4v supply

2) Yes, tie all the grounds together

3) You might want to check out the Adafruit Motor Shield. This has 2 H-bridges and can drive 2 steppers. There are tutorials for how to connect everything. http://www.ladyada.net/make/mshield/

adafruit_support_bill
 
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Please be positive and constructive with your questions and comments.