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Noob trying to power the Propeller Activity Board with a battery pack — Parallax Forums

Noob trying to power the Propeller Activity Board with a battery pack

bubby9534bubby9534 Posts: 36
edited 2015-04-04 12:36 in Propeller 1
I have a project where I'm using my Propeller to override a hobby R/C car's control unit. I want to use the car's power source to power the Propeller. The power source in the car is 6V 2000mA.
I know the voltage should be 6-9V to properly run the Propeller Activity Board, but does the amperage matter? 2000mA seems like a lot.

Comments

  • Cluso99Cluso99 Posts: 18,069
    edited 2014-12-06 15:02
    The car source will be fine. Even if you load up the prop with a lot, it won't use anywhere near 2000mA (2A). For what you describe, its likely that you will use quite a bit less than 100mA.

    What is more likely is interference over the power lines from the car's motor. If you find this, connect the 6v using a series inductor.

    Keep us informed with your progress here. If you have any questions, don't hesitate to ask. There are plenty of knowledgeable people here willing to help.
  • PublisonPublison Posts: 12,366
    edited 2014-12-06 15:07
    bubby9534 wrote: »
    I have a project where I'm using my Propeller to override a hobby R/C car's control unit. I want to use the car's power source to power the Propeller. The power source in the car is 6V 2000mA.
    I know the voltage should be 6-9V to properly run the Propeller Activity Board, but does the amperage matter? 2000mA seems like a lot.

    The amperage from the battery is what it can supply. The amperage that the Activity Board will need depends on the components on board.

    Don't worry about to battery's capacity to deliver 2000ma, the Activity board will only use what it needs. You will not over drive it.

    Edit: Ray types faster than me. :)
  • bubby9534bubby9534 Posts: 36
    edited 2014-12-06 15:18
    Ah, good to know. I'm brave enough to hook up the power now.
    I suppose I should provide some background. I have a Traxxas Slash R/C car and want to automate it by replacing the radio reciever with my Propeller board. Since the speed control and servo on the car have standard three-pin connectors that plug into the three-pin connectors on the top of the board, it'll be easy to interface with the car.
    One issue I'm encountering is that when I attempt to control the servo, it won't respond at all like I expect when using the servo control library (I'm using C). I wonder if it's because it doesn't have enough power or is controlled differently.

    If I change the 3-pin header toggles from 5V to Vin, the servo I plug into the header will get as much power possible from the power input to the board, correct?
  • NWCCTVNWCCTV Posts: 3,629
    edited 2014-12-06 16:37
    bubby9534 wrote: »
    If I change the 3-pin header toggles from 5V to Vin, the servo I plug into the header will get as much power possible from the power input to the board, correct?

    Careful, depending on the Servo too much over 6 volts will cause the magic smoke to pour out.
  • bubby9534bubby9534 Posts: 36
    edited 2014-12-06 16:41
    Since I'm powering the board with the R/C car's line already intended to go to the servo, I think it'll be getting the intended power.
    I'll post this project with photos eventually so I can demonstrate what I'm trying to do.
  • Cluso99Cluso99 Posts: 18,069
    edited 2014-12-06 18:05
    As said, be careful with servos and giving them more than 5V.

    You might try removing the load (mechanical) on the servo and test to see that the servo is working correctly. You need to get this far first up.
    There are some servo demos in the obex.
  • bubby9534bubby9534 Posts: 36
    edited 2015-04-04 09:57
    I've finally re-gained interest in this project. Here are some photos of what exactly I'm working with.
    Diagram.jpg

    Wiring.jpg


    My overall goal is to replace the receiver unit with the Propeller. What I've accomplished so far is powering the Propeller board with the 6V Regulated Cable from the motor controller, and I managed to get the servo to make incoherent movements. At this point I just need to figure out how exactly the receiver interfaces with the servo and the motor controller, and get the Propeller to mimic that so that it can control those things autonomously.
    Diagram.jpg
    1000 x 750 - 225K
    Wiring.jpg
    1000 x 750 - 192K
  • PublisonPublison Posts: 12,366
    edited 2015-04-04 12:14
    There are many RC objects in the OBEX:

    http://obex.parallax.com/search/RC

    One that i have used in the past is:

    http://obex.parallax.com/object/505
  • LoopyBytelooseLoopyByteloose Posts: 12,537
    edited 2015-04-04 12:36
    Just a friendly mention -- some of newer, tiny servos - the Pico-servos will only tolerate 4.8 volts.
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