I'm in the middle of writing embedded software for a 19'' rack mount LED lighting driver. The product includes a momentary rocker switch used as a soft power button which allows the user to place the unit into and bring it out of low power standby mode. A rocker switch was chosen to make the styling match our other products which have toggle rocker switches to control power.

The type of switch used on this device

At the moment I have made it so the soft power switch needs to be held for 1 second before the system will change power states. It's been brought up by our technical manager that having to hold the switch seems counter intuitive (to him) and it should react instantly. I've argued that as this system could be powering emergency lighting having a delay on the switch to prevent accidental activation is a good idea.

What experience do other people have with soft power switch and how much of a delay to add to them? Is this likely to differ between the intended use of products?

1 Answer 1


I'd say it depends on the impact of accidental pressing of the switch and whether the action invoked by the switch is incidental (now and then) or reasonably frequent. For the first one I'd opt for 3 seconds (try it for yourself), for the latter it should be immediate.

Also, I'm curious if the button acts for power-off only or for toggling between off and on. In the second case I'd suggest you put dual momentary switch in:

dual momentary switch from Internet

  • 2
    Thanks for the reply. The system is probably going to be left on 99% of the time with occasional powering off for maintenance. I think he's come round (or at least been out voted) on having the delay on the switch. I think a part of it is we asked someone who hadn't had any involvement with the project up to this point to turn one on and he just held the switch untill it came on, which disproved his theory of "It would confuse people" quite effectively.
    – RobbG
    Apr 11, 2017 at 15:32
  • 1
    Good to hear that. Good luck with the project!
    – Mike
    Apr 11, 2017 at 20:40

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