Need some Servo advice.

David BoccabellaDavid Boccabella Brisbane, Australia Moderator
Hi Folks.
I am using one of the Adafruit PCA9685  to control 16 servo's in my costume.  One of the things is that you can set it to 'turn off' a channel or send no pulse to it.
With some servos this causes the servo to turn off so it can move if not under load, others servos will continue to try and keep position.
With R/C planes I can understand the precision needed but when working organically you don't need that level of precision, or you can let the fabric and servo arm drift back to it's natural staying position.

For instance - my ear servo will pull the ear fabric down to simulate the ear lying back. with power off the servo gearing holds the ear down.. however if I leave the servo on it buzzes to keep the micro-positioning.

Has anyone working with a list or brand of servos that will turn off when no signal, rather than hold last position set..

Many thanks
Dave

Comments

  • Chris EllerbyChris Ellerby Los Angeles Admin
    Hi Dave,

    I'm not familiar with servos that shut down with no signal, but I would be interested to find out if there are any!

    /Chris
  • David BoccabellaDavid Boccabella Brisbane, Australia Moderator
    I have found a couple.  I will send you the info when I find my notes.

    Of interest I am considering making a daughter board for the Adafruit 16 channel PWM Servo controller

    It will have dual 74ls595's  with the outputs controlling a MOSFET each. That way a servo can be powered down after the position is reached rather than being on and possibily seeking.

    It will fit under the existing Adafruit board and require the negative pins for the servo's to be desoldered and removed, The pins removed, and the hold drilled out removing the Adafruit boards negative servo connection. The daughterboard will have pins that will go through those holes and provide the power and switching to the servo's via N-MOSFETS.

    Should only use a couple of extra pins from the Arduino/whatever

    Do you have an idea of the current your servo's use?  
    Dave
  • Chris EllerbyChris Ellerby Los Angeles Admin
    I've never monitored the current on my servos.

    /Chris
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