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Proto Board Overload??? — Parallax Forums

Proto Board Overload???

mspeediemspeedie Posts: 12
edited 2009-11-12 16:28 in General Discussion
I'm using the SX28 Proto Board with an additional SX28 chip connected (2 SX's total). I also have the board's Vin driving a 12V DC motor.

The second chip is acting funny and I'm wondering if my regulator or capacitors are being overworked. I've put the second chip on an SX Tech board and it seems to run fine.

My power supply is a 400mA 12.5V (I know the board says "6-9 VDC but I was told that limitation was so servos and other accessories, which I'm not using, will work properly. I believe the onboard regulator can handle higher voltages than 9V).

I'm wondering if I just need a higher amperage power supply or if I need to upsize the capacitors or regulator on my Proto Board.

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2009-11-12 15:28
    1) Motors are inherently very noisy and electrical noise gets into other parts of the circuit. If you want specific suggestions, you'll have to post a schematic of the setup you have. Make sure the schematic is of what you actually have, not what you think you have. They're sometimes different.

    2) The 9V limitation is mostly due to heat considerations. If your circuit draws any appreciable amount of current from the regulator, all that extra voltage becomes heat and the regulator will shut itself down to prevent damage from excessive heat.

    3) Never just add a larger power supply or change the capacitors or regulator unless you first understand what's going on. You may find that there's a simpler solution and the changes you mentioned may not fix the problem and may even damage things. The last thing you want to do is to try a solution that involves cheap parts and end up damaging the expensive parts.
  • RobotWorkshopRobotWorkshop Posts: 2,307
    edited 2009-11-12 16:28
    What do you mean by "acting funny"? As Mike mentions you need to give us some more information so that we can help you. The built-in regulator on the SX28 Protoboard should easily power two SX28 chips. How are you mounting the second SX28 and how is it wired? What speed are you running it at and how is the clock configured? Are you using an external resonator? Do you have a pull-up resistor on the reset line of the second SX28 or have that line tied to the reset of the other SX28? If it is floating that may make it act odd.

    In regards to power it sounds like you are pulling off the motor power before it enters the voltage regulator. With that you avoid the motors taking too much out of the regulator. However, if the motors draw a lot of current then the voltage may drop whenever they turn on and it can drop low enough for a fraction of a second to cause issues with your logic.

    If you can post pictures and a schematic that will help.

    Robert
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