Car speedometer trigger

I need to create a solenoid that triggers and blocks 2nd gear in a car at certain speeds. (Our race car a 2000 Celica GTS has a bad shifter design)
At any rate I’ve triggered solenoids before but am wondering what I will need to trigger it based on the frequency coming from the speed sensor or if I will need to convert it to a frequency before hand. More details on how the sensors work here. Speed Sensor - an overview | ScienceDirect Topics

Basically I just need it to trigger at a certain frequency and the pull back when under that frequency again.
Thanks for any help or ideas you have.

Welcome to the forum.

The information about the sensor is a science book. Do you have a datasheet of the actual sensor you have?

Generally microcontrollers have timers that can be used to measure frequencies using a feature called capture compare. You basically compare an internal clock with the signal coming from the sensor. There are few things that need to be solved. The signal output voltage from the sensor must match the input capabilities of the microcontroller used and the speed must be within a range that can be handled. The sensor datasheet should answer these questions.

Additionally automotive electronics lives in a rough environment. That is something you will need to take care of as well. Just google car Arduino destroyed. :slight_smile:

Thanks. I think I am just going to go this route and save myself some hassle with the programming.

And considering both the time you would spend in researching the necessary interface with the speed sensor, constructing the interfaces and then arranging the coding, the already well-tested and presumably reliable design sounds like a much more practical choice. :+1:

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