This was my very first interface that I used.   I was contacted by the pathfinder director of my church and he asked if I could build a new timing interface!   I told them that I couldn't but I could connect the track up to a computer and keep track of the timing of the cars that way.  He thought that would be a good idea.  So within two weeks I had a full interface ready for the next derby race!

I had already made this device before he asked to help him for the derby.  It was designed as a Digital camera interface.  The problem is that I ran out of money!!  I needed more than a $100 to finish the project!

After finishing the race with my first interface I was informed that they would enjoy a more accurate and usable system!  So I created v2.0  it had support for sensors at both the top and the bottom of the track to keep track of what lane the cars were on.

Unfortunately this interface was very slow. It was using the parallel port a very fast port, but sending serial data through it.  Because of  this it was performing much slower then what it could.

I next came up with this interface to fix the drawbacks of v2.0.  It now will talk to the computer in a full parallel port configuration and speeds up by almost 4 times as fast as v2.0.   This improvement comes from the fact that fewer chips are required and it used the full parallel port.  It only used 3 ICs instead of 7.

It is also fully digital.  In v2.0, I used relays to control the sensors and gate control.  These have been replaced with transistors.

Also the interface does not need an expensive sensor setup as v2.0 needed.   Power for this device was originally provided by a transformer.  But by accident, while working and testing it I noticed that it would  work (although not that well)  without the power cable!  It was getting it's power from the computer.  So after a few more modifications and program upgrades, I modified v3.0 to be powered by the computer!  This was fully accomplished with version 3.1 (below). 

This was my first interface that would be somewhat easier to make multiple copies of.  I made a total of two of them to take to Oshkosh Wisconsin.  I ended up only using one of them because our other track did not turn out to be good enough to race cars on!

This also was the first interface to be fully powered by the computer.

v3.4 - 2000

Now I have finally built a solid device.  So I took the plunge and designed a printed circuit board.  I had six of them made.

This would be the first production project that I have made that I could actually sell and distribute to others.  It wasn't constructed in such a way that it would have problems with a part coming loose or have cold solder joint.  Because all previous interfaces to this one where built with point to point soldering of each wire and connection into place.  It would have been easy for a solder joint to come loose especially the ribbon cable connections.  This is why I have socketed them!

This new circuit has an expansion socket and power supply support on it.  But after working with the parts I found out that I really did not need this.  I could build expansion cards right off of the ribbon cable that connected to the computer.

v3.4b - 2001

Any project is not complete until it has a full box for it.  So I have found a box that it would fit into with very little modification to the circuit board it's self.

The interface could now be shipped in a kit form.  With the box, circuit board, and parts all in pieces.  And have the pathfinder club put the parts together to build their own interface.  Or I could sell a fully made kit that was fully tested and ready to use out of the box.

After some testing I found that v3.4 did not work on some old Parallel ports because thy did not supply the correct voltage levels that the interface needed.  Because of this I have modified the type of chips I use so the interface will now work with any parallel port that exists.