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Relay speed — Parallax Forums

Relay speed

model14model14 Posts: 3
in General Discussion
Any idea how fast the Parallax relay board 27115 can be cycled? I'm thinking of using it for PWM output to control the speed of a 12 volt, 5amp brushed motor.
Thanks,
Richard

Comments

  • model14model14 Posts: 3
    I'm having trouble understanding the data sheet with respect to frequency for PWM. For my use 60 HZ should be plenty fast.
  • Mike GreenMike Green Posts: 23,101
    I strongly suggest using either a motor controller or Power-FET for this job. Even if a relay were fast enough, they have a limit on the number of cycles, particularly under load, before the contacts become pitted from arcing to where they don't work.
  • kwinnkwinn Posts: 8,697
    Mike Green wrote: »
    I strongly suggest using either a motor controller or Power-FET for this job. Even if a relay were fast enough, they have a limit on the number of cycles, particularly under load, before the contacts become pitted from arcing to where they don't work.

    +1. A relay is a very poor choice for PWM
  • ercoerco Posts: 20,253
    +1. Yup, yup and yup to everything said. If you're new to this game you could even use a brushed ESC (RC car speed control) which is ready to go and can be controlled with servo commands or PULSOUTs. For instance, this one could work for you if you don't need reverse: https://hobbyking.com/en_us/turnigy-20a-brushed-esc.html
  • model14model14 Posts: 3
    Okay, got it, thanks for the advice. I'll take it.
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