I've got this rev limiter I'd like to engage with one momentary switch and turn off with another (momentary) one. It would be turned on or off for extended periods of time. Ideally, this contraption wouldn't use electricity when the vehicle is turned off.

  • \$\begingroup\$ Draw out a schematic or block diagram of what you already have, and one where this "rev limiter" is where you'd like it to be. \$\endgroup\$ Jun 23, 2018 at 18:32
  • \$\begingroup\$ A hint - think "relay" \$\endgroup\$
    – Maple
    Jun 23, 2018 at 18:34
  • \$\begingroup\$ @IgnacioVazquez-Abrams Wiring the rev limiter to the ignition system is no problem. The thing is I would like to replace the original toggle switch with two momentary switches - One to turn on the rev limiter with and one to turn it off with. After pushing button number one the limiter will stay toggled on. To turn it off you would have to push button number two that I will hide in a good spot. \$\endgroup\$ Jun 23, 2018 at 18:53

1 Answer 1


You need a latching relay

This type of relay does pretty much exactly what you want, changes between two outputs states as a result of a short pulse on it's input. If you get a "dual coil" or "double winding" type then there will two inputs, one called "set" and one called "reset". The set input turns the output on, and it stays on until the reset input is used, which turns the output off.

There are some designs of latching relay which latch mechanically (as opposed to magnetically), and these don't need any power to stay on, so wouldn't drain the battery when the bike is off.

The relay will need it's set and reset inputs to be on for a minimum period in order to switch, probably some milliseconds. You can either include some digital circuitry to make sure that is the case, or just hold the buttons for half a second when you press them.

  • \$\begingroup\$ +1 This is a good lead, but be sure to check the vibration/shock resistance, many of them are not recommended for vehicle applications. \$\endgroup\$ Jun 23, 2018 at 19:03
  • \$\begingroup\$ @spehro pefhany Allright. Do you know any reliable relay manufacturers that make relays that would work for applications like this? \$\endgroup\$ Jun 23, 2018 at 19:39
  • \$\begingroup\$ @KalleHiltunen Not offhand, you can go through the datasheets and compare. \$\endgroup\$ Jun 23, 2018 at 19:47

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