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Marcs Electronic Gizmos


Solenoid Operated Gearshift

This is designed to drive two car-starter-motor solenoids to actuate the gearshift arm. For details on the mechanical arrangements used please visit my build site Marcs Build Diary

I am providing a basic circuit and basic software to enable people to develop this design if they have the facility (programmers, compilers etc).
Note that the software is very basic but HAS been tested with the hardware described. My own software is now rather more advanced but there is enough to get someone started.

The Circuit

The design is based around a PIC16F84 microcontroller.
The basic system supports 2 steering-wheel mounted switches , 2 high-current solenoid drives and a 7segment LED display to display the current gear.
To allow lots of switches and connections to the PIC I have implemented the 7segment drive via a shift-register.

To view the schematic you will need an Acrobat PDF reader. You can get one Here

PDFfile Gear Controller Schematic (Acrobat PDF File)

The Code

The code is VERY basic. I have now added many more functions to the software such as auto use in either manual/auto systems, end-stop switches to determine succesful changes, and improved switch routines.  These will not be released here- it would take the fun out of developing things for yourself!

Zipfile Gear Controller Software v1.0



Here are a couple of photos of the test setup. They show the solenoids, the steering wheel buttons and the LED display.

Does it work?

In a word - No.

When I tested it on the car I could never arrange the levers such that there was enough force AND distance to do the job 100% reliably. Sometimes it would change gear, whilst others it just jammed on.

With some time and experimentation I think the idea is a winner. But I do not have the time any more. In any case I could never sell on the units since the liability requirements for providing active control systems into the automotive market are extreme.



You are free to use this design for your own personal benefit. You are NOT entitled to use this design as a basis for a commerical product. If you wish to do this you MUST contact the author and ask permission.

I am in no way responsible for anything that happens with you using/reading this article.  If you fall off your chair - that's down to you.  If you burn yourself soldering - that's down to you.  If you blow up your engine - that's down to you.   Anything else, yep, you guessed it - that's down to you!