How divide / multiply low frequency pulses to create a new frequency

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Thread Starter


Joined Sep 26, 2013
I need to build a replacement Vehicle Speed Senor. The drive gear in my Subaru gear is dead and requires gearbox removal and disassembly to replace it. I intend to set up a hall effect sensor on the drive axle output.
The Engine management system requires approximately 4 pulses per axle rotation so 4 magnets are required. Sadly for some reason the magic number is not exactly 4. So i will need to divide or multiply this signal to get the speedo to read correctly.
So now I am here in search of a circuit to do the required signal frequency modification.
At this point in time i have no idea what X/÷ factor should be.

I am hoping someone can help me with a circuit.

Many thanks


Joined Aug 23, 2012
Welcome to the AAC forum.

The owners of All About Circuits has elected not to host discussions of automotive electrical system modifications/enhancements due to safety concerns, the potential of legal ramifications and the possible circumvention of vehicle regulations at the state and federal level.

This thread is against the AAC forum rules, Terms of Service (ToS).

Any kind of over-unity devices and systems
Automotive modifications
Devices designed to electrocute or shock another person
LEDs to mains
Phone jammers
Rail guns and high-energy projectile devices
Transformer-less power supplies
Terms of Service (ToS).

Automotive modifications of any kind are strictly forbidden. Therefore, this thread will be closed.

Please try to understand the reasons behind this action, and feel free to browse and use the forums.

You might find answers to your questions in one of these forums:

Another good forum that shares many of the same membership is .

Good luck.
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