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  1. #11
    Quote Originally Posted by 2e0poz View Post
    DC motors may be a problem with this type of setup?
    I think it would, it’s the power demands, the servos have much smaller DC motors than the final drive ones, same as the propeller motor on a helicopter would be drawing at full revs almost the entire power output. A board like that would be excellent for servos that are on/off and small, but I think the motor shield somehow manages to distribute the power a lot better, who knows though lol ? This is all new to me. I do have a servo and sensor shield I could try it , but I expect they made a motor shield for a reason rather than just have one sensor – servo – motor board.. don’t quote me on that it’s just a feeling
    I've seen a video somewhere where you can use a small heat sensor that regulates the fan speed via Arduino code.

    Fiction is far more plausible when wrapped around a thread of truth

    Nothing great was ever achieved without enthusiasm.
    Ralph Waldo Emerson

  2. #12
    ecat's Avatar
    Location unknown. Last Activity: 08-02-2014 Has been a member for 6-7 years. Has a total post count of 157. Received thanks 5 times, giving thanks to others 8 times.
    If you need more servo outputs it should be possible to combine the Adafruit board with this idea ...

    Drive 10 Servos using only 2 Arduino Pins - DIY Drones

    You need to remove the servo drive code from the Adafruit library and change the linked 4017 code to use pins 9 and 10 instead of 9 and 8, then connect the 4017 circuit to the Adafruit servo 1 and 2 control pins. This would give you 4 motors and up to 10 servos at an extra cost of around £2. I've used the 4017 idea before with a PIC32 controller, it worked well.

    If instead you just need to drive one more motor/solenoid you could use a transistor on one of the free d0, d1, a0..a5 pins to give a single direction drive, or two of the pins + an inverter chip and another L293D, as on the Adafruit board, to drive 1 motor both forward and backwards.

    And if you wanted to be really sneaky you could perhaps wire a 2nd Adafruit board up in parallel to pins d4, d7, d12 and GND but connect one of your free pins to the second boards d8 connection and get yourself an extra 4 full motors - N.B. Each additional motor will also require one of your additional free pins and some code to drive it for Enable/Speed control. Again you would need to modify the Adafruit library but the changes shouldn't be too tricky*.

    *Shouldn't be too tricky*: the famous last words of many a programmer :(
    Last edited by ecat; 01-10-2012 at 03:01 PM.

  3. From my experince a few (read many) years back of creating an autonomous robot, keeping the drive motor control seperate from the servo control is critical for reliability. Personally I'd use a multi-way PWM output shield to drive the servos and two channels of that to drive external PWM controllers for the motors. That way you can keep the Arduino and low curent systems away from the high current and position the motor controllers to optimise (e.g. shorten) the high current wiring. Also motors controllers have a habit of going pop and keeping them seperate can save money in the long run.

  4. #14
    ecat's Avatar
    Location unknown. Last Activity: 08-02-2014 Has been a member for 6-7 years. Has a total post count of 157. Received thanks 5 times, giving thanks to others 8 times.
    Quote Originally Posted by irving2008 View Post
    From my experince a few (read many) years back of creating an autonomous robot, keeping the drive motor control seperate from the servo control is critical for reliability. Personally I'd use a multi-way PWM output shield to drive the servos and two channels of that to drive external PWM controllers for the motors. That way you can keep the Arduino and low curent systems away from the high current and position the motor controllers to optimise (e.g. shorten) the high current wiring. Also motors controllers have a habit of going pop and keeping them seperate can save money in the long run.
    Wise words indeed. Never underestimate the latent malice of electric motors.

    A bit of easy reading for when random failures occur:
    http://modelsolutions.ca/articles/Da...eMarch2006.pdf
    http://www.fightingrobots.co.uk/docu...Guidelines.pdf

    I'm quite new to all this motor stuff but my feelings are:

    1) If you can use a servo then use a servo. Servos are designed to be mechanically and electrically robust while playing nicely with the rest of your electronics.

    2) If you can use a brushless motor + electronic speed controller then do so. Expensive but efficient and while the ESC will generate electrical noise it is easier to manage than the all-out circuit frying shotgun blasts of...

    3) Typical, cheap brushed motors. There are two at the front of the tank in the first post picture. Use caution, read the links and good luck.

    At the risk of stating the obvious, all of these models are designed to be powered by batteries, batteries that are designed to deliver massive amounts of current as and when required. Even a small electric motor may pull 1Amp while running under load, and more when changing direction. Stick 5 such motors in model and a typical 'made for models' battery will handle the 5A or more current with ease, the same cannot be said of the typical wall/mains adapter you may use in place of the battery while messing about - expect random resets. And don't even think about running the whole shooting match from a USB port!

    But you, yes, you random reader who I know won't listen to that last bit, will you? You watched a clip on YouTube of some random running their motor(s) from an arduino + USB connection. It worked for them so it will work for you, obviously. They also know a lot more than I do too, obviously, they have a video! Good luck, USB should protect itself and limit the current to about half an Amp after which things may randomly stop working or reset or your PC may start smoking.

    Last bit, honest.
    So you have your motors running off a battery supply and you have wired your arduino to run from the same batteries. Is it ok to plug in the USB connector, or one of those neat 6 pin breakout boards? The battery is supplying voltage and the USB connector wants to supply 5V so what happens when the two meet up? The answer is, I don't know. Perhaps it depends on the flavour of arduino, perhaps it doesn't matter, perhaps... On my 6 pin Mini Pro I just don't connect the 5V pin, in general I think it a good idea to always disconnect the arduino battery/external supply before using USB.

  5. #15
    Quote Originally Posted by ecat View Post
    Wise words indeed. Never underestimate the latent malice of electric motors.


    Last bit, honest.
    So you have your motors running off a battery supply and you have wired your arduino to run from the same batteries. Is it ok to plug in the USB connector, or one of those neat 6 pin breakout boards? The battery is supplying voltage and the USB connector wants to supply 5V so what happens when the two meet up? The answer is, I don't know. Perhaps it depends on the flavour of arduino, perhaps it doesn't matter, perhaps... On my 6 pin Mini Pro I just don't connect the 5V pin, in general I think it a good idea to always disconnect the arduino battery/external supply before using USB.
    Thanks ecat, yes thats why I have all the baords powered, and I to dont know the effect of having power and pluging in the 5v USB, but I hope that once all the wireless stuff is up and running I can swap to total independant and use the wireless to program the board (as seen on youtube :) )

    One of the things I want to attempt is to switch between two cameras using a relay, in theory it should be easy, but I bet it wont be.

    Fiction is far more plausible when wrapped around a thread of truth

    Nothing great was ever achieved without enthusiasm.
    Ralph Waldo Emerson

  6. #16
    Quote Originally Posted by Fivetide View Post
    I'm saying nothing lol :) but your not far off the "Mark"


    Hence why Iím thinking of swapping cameras to

    1/3 SONY Colour 700TVL CCD Waterproof Camera, IR Distance: 50m

    Give me more of a Stealth ability at night lol !
    be careful splashing loads of cash on posh branded ccd .... in my experience all things being equal (chip size and lens quality) i never could tell the difference between a branded and a ten bob ccd board
    they all seemed to "hunt" for white balance etc and the picture quality tends to be pretty bad.
    i used to stick them in a paraglider wings during flight before gopro got its act together :)
    make sure you get a slack hand full of lenses one really wide one 150+ degree field of view would probably earn its keep (standard threads are 12mm x 0.5mm pitch)

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