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Re: sumobot board Voltage capability — Parallax Forums

Re: sumobot board Voltage capability

joy1joy1 Posts: 32
edited 2012-01-09 18:53 in Robotics
I've been modifying a sumobot using dc motors and esc's. We are using two motors (per side) attached to each esc and an 11.1 V LiPo battery running the two motors.
We have tied the board to one of the 11.1 V batteries. Can the sumobot board handle 11.1 V?

On another note...we are not having much luck with PING on the sumobot. Is there something I should know?

Mike, you said it will not affect my board...will it affect the PING? or...does the PING need to be on vdd?

thanks

Comments

  • Mike GreenMike Green Posts: 23,101
    edited 2012-01-04 12:29
    Applying 11V to the PING will destroy it. The PING requires a regulated 5V supply which the regulator on the Sumobot board can supply as Vdd. The amount of current drawn by the PING puts an additional load on that regulator and, if you're trying to run the regulator off 11V, may cause it to overheat. The best thing to do would be to use a 7806 voltage regulator to reduce the 11.1V to 6V which the on-board regulator can handle. Check a datasheet for the 78xx regulator series for sample circuits. You probably will need a heatsink for the 7806 regulator.
  • joy1joy1 Posts: 32
    edited 2012-01-04 12:36
    Are the connections that the QTI's are connected to on the sumoboard regulated to 5V? If it is, could I plug the PING into one of these connections for it to work properly?
  • Mike GreenMike Green Posts: 23,101
    edited 2012-01-04 12:40
    The regulator on the Sumobot is rated for 50mA output and, although the Stamp itself on the board uses only a few mA, the LEDs draw several mA each and that adds up. The PING uses 30-35mA and the total current used could add up to more than 50mA. You may need a separate regulator for the PING or you may need to replace the LM2936 regulator on the Sumobot board with a higher current 5V regulator. If your ESC requires a separate 5V logic supply, you certainly would need some other source of regulated 5V for the ESCs, PING, and Stamp together.

    I'm not sure how the QTIs are connected. Maybe to the AUXn connectors? In that case, the QTIs are powered from a Stamp I/O pin which can supply slightly less than 5V at currents up to about 20mA. This comes indirectly from the Sumobot's 5V regulator. These connections can't supply enough for a PING.
  • joy1joy1 Posts: 32
    edited 2012-01-09 18:53
    So do you think I could run a board with one ping and two qti's without overheating? I'm not sure about changing voltage regulator since I haven't the experience...is this hard?
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