Electronic Finish Line - Make or buy your own

CooksProjects Monday, 4/12/2021

Chaos Canyon (of YouTube DSPN fame) has recommended that I post here about a Race Start timer and speed measuring device for Hot Wheels style diecast cars I have made.  I initally made it for my children and to clearly show the winner when we raced Hot Wheels cars down track placed on the stairs!

More detail can be found at our website: www.cooksprojects.com where we can now sell you a per-made product.

Infrared light is used to detect the cars crossing the unit.  As there are no moving parts, not only is the accuracy of the measurement maximised but also no damage is caused to the car by impact to flaps (unless it comes off the track and hits the box).  The unit is self-contained and easily transportable as well.  All that is needed is a USB power supply, or a laptop if you want to record the extra data.  Make this device and there is no longer any doubt on which car won a race.

My Race Timer design can start a race, measure the time taken from lights out to complete the circuit and show the winning car, along with the speed difference to an accuracy of 1 millisecond or 1/1000th (0.001) of a second (Formula 1 accuarcy).  With some software tweaks (included in download), you can have a dual function unit that can be a Race Timer and also become a speed trap which measures the speed of each car as it passes through the gate.  Using this optimised fimware, the theoretical maximum detectable speed of a car is 288Km/h!  This information is immediately displayed on the onboard LCD display and the data can be sent to a computer via the USB link for use in a Redline Derby!

You can see a short demo of the unit on my YouTube channel, CooksProjects.


The race timer starts with a grand prix style audible start sound and flashing light sequence.  As the first car passes the sensors, the winning car's lane LED is turned on.   Using the onboard LCD display, the winning race time and time difference between the winning and losing car is displayed in thousandths of a second.  After a short delay, the individual car’s actual speed is shown (Km/h), followed by the scale speed of each car (based on Hot Wheels scale of 1:64).  The timer then resets for another race with the race start sound and lights sequence.  If the second car does not pass the sensors within 10s of the first car passing the sensors, a crash is assumed for the second car and the winning lanes times and speeds are displayed before resetting for another race.  The theoretical maximum speed the unit can measure as a Race Timer is 144Km/h with a time accuracy of up to 2ms (based on Arduino Uno).

Data can be transmitted to a computer via the serial interface to reveal more detailed information, including actual times in milliseconds.  This could be used as a record in a Grand Prix style event or for comparing different cars characteristics.

Further development of the software has resulted in a dual function unit that is capable of continuously recording the speed of multiple cars passing the sensors or the race timer mode as above. The main difference when operating in the speed sensing mode is that the speed of the last car in that lane is displayed continuosuly until the next car traverses the sensors and it's speed is displayed.  This data can be sent to a connected computer as well.  The device will continue detecting cars and displaying the speed until power is removed.  The theoretical maximum speed the unit hardware can measure in this mode is 288Km/h due to the faster, optimised firmware detecting loop. 

A detailed instruction booklet providing technical drawings of the casing, more detailed instructions and hints on how to build this project as well as the limited release source code for the dual function Race Timer and Speed Measurer functions is available for a small fee:
Get the booklet and software at Cook's Projects shop 
(The design dimensions are based on normal orange track and cars less than 60mm high.  The booklet assumes a basic knowledge of electronics and the Arduino IDE.)

If you have any suggestions for improving the functionality of the unit, or adding additional features that may be of benefit to the more decerning racer, please let me know!  Add your comments here or on our YouTube channel.  To get notification when the other products we have in development go live, don't forget to subscribe to our YouTube channel. 

I hope that this project inspires someone to make up the Race Timer.  Please post your results on the CooksProjects YouTube channel or website (soon to be developed - links will go on CooksProjects Channel first).

Now there can be no doubt on which car is the fastest! 

A more detailed video on how to make the Timer is at:

How to Make a Race Timer/Speed Measurer for Hot Wheels style cars

You can also see us using the design as a Speed Measure in this video (2:40 into video):



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Chaos_Canyon 4/12/21

Brilliant. Thanks for posting. 

Due to customer requests, we have now invested in the production of a self-contained working Race Timer and Speed Measurer as a commercial product.  Our current production run is limited, so if you are interested please visit our new website to find out more.


If you might be interested in purchasing the final product, we encourage you to join our waiting list at the website.  It is completely free and you are under no obligation to purchase when the product is available.

  • If you're interested in a review of the product, just PM and we can make it happen. — redlinederby

The first batch of Race Timers are nearing completion and we hope to be able to offer them for sale by the end of June.  The intial production volume is very small.  We have a waitlist available in www.cooksprojects.com for anyone interested.

There is a short video showing the new features at:


Thanks for your attention.

We have received some queries about the Race Timer and Speedometer from our early adopters (the Race Timer will go on public release on 24 June 2021).  I thought that it might be useful to include one here and see what the community thinks may be a solution.

Is there a way for the timer to initiate a start gate? There will be variance due to different reaction times and you would not be able to see consistency with the car times due human error.

Our timer does not initiate a start gate.  This would be a separate project.

A race is traditionally measured from when a start gun, flag or lights go out and the reaction time is part of the race.  This is what happens on Formula 1 races and is exactly what the Race Timer and Speedometer does.  Indeed, the light and sound start sequence is modelled on an F1 style start.  The only difference is there isn’t the random interval from final light lit, to all lights going out as there is no way for the Timer to know if a jump start occurred.  So the Race will start at exactly the same time interval after the sequence begins and the user will become familiar with the cadence.  The time is continuously measured from lights out until the first car arrives – this is the Race Time.  The time difference is also shown between the 2 cars arrival times as well as each car’s speed at the finish.  Greater detail/accuracy is available if the datalink option is chosen; there are not enough digits on the LCD to display that information and the post race delay in doing so would become tiresome for many.  If you need that accuracy, then the datalink option will provide it.

 If you are interested in measuring the exact timing of a car, the Race Timer and Speedometer will still do that.  It can very accurately measure the difference in time and speed of each car at the finish point.  So if you have a manual device that can release cars on all lanes at the same instant, the result, in time difference and speed, will be accurate for each car.  If you know the length of track, then you can calculate the difference in acceleration of the 2 cars.  But all this would have to be done manually or on a computer.  You would not be able to accurately determine the time the car has actually run on the track (track running time) as this would include the reaction time of the user (race time).  However, with a simultaneous release, the reaction time would be the same for all cars and allow for comparison of individual car, or track, characteristics.

We have looked at the race start gates provided by Hot Wheels.  Even these mechanical devices do not release each car at ‘exactly’ (to the microseconds we are measuring) the same time.  Due to the bend in the mechanism, the outer cars normally get released later.  So an accurate start gate and starter system is a project all on it’s own!  May be something for the future?

Effectively, you are asking for a time over a measured distance.  The Race Timer and Speedometer provides this.  The difference is, your measured distance is the whole track, whilst the Race Timer and Speedometer’s measured distance is the 80mm it straddles.  This allows the unit to be entirely self-contained, and without external wiring – except the power cord.

I hope this answers your query and thanks for your interest.

How do you work out how good your modifications are?  Using a stopwatch on a track will show the big changes, but fine tuning your setup requires a more precise method.  After spending hours enhancing your car are you sure that it is the most efficient it can be?

After reading some of the posts on this website and responding to FAQs from our users, we decided to help.  We have developed a spreadsheet that will analyse the energy used by a car on a particular track.  Using this data, we can quickly reveal how mods have improved, or reduced, the performance of a car or the track.  We can also review our car collection to find the most efficient car in the group.

The Car Performance and Energy Calculator spreadsheet is available as a free download at www.cooksprojects.com.  There is a video on how to use the spreadsheet to help analyse a car's performance on YouTube.  Watch Video here

There are a few devices on the market that will measure the speed of your car.  But many require modification of your track or long wires.  Some are expensive.  But as long as you can obtain a precise and reliable measurement of the speed of the car at a certain point, you can use this spreadsheet to show how efficient the car, and track, are.  You can use this free download on any application capable of running spreadsheets saved in the excel format. 

The device we used to measure the car speed is the Cook's Project Race Timer and Speedometer (available at cooksprojects.com).  It is an easy-to-use device that simply needs placing over the track and powering up.  No long wires or track modification are required.  Nor do you need to measure the track length.  The device can start a race with an audio and light sequence and measures the time taken and the speed of each car instantly and accurately revealing the winning car.  When it is used in Speedometer mode, the unit concentrates on measuring the speed of the car to within 1/100,000 of a second and instantly provides the speed in Km/h.  There is also a datalink version that not only outputs more precise information to a connected computer, but provides more detail on the race and displays mph and m/s speeds.  The datalink version also allows for the data to be easily copied and used in other applications.  You can check out the detail of the race time here

  • That all sounds fantastic! Yet ... I´d still have the function of timed runs from start to finish. Is it possible for you to add this feature? ;-)) — Bavarian_Diecast_Racing
  • Hi Mark, Thanks for your question. The new V2.0 design of the Race Timer, finish line and Speedometer can do this. Each race, or run, is timed from start to finish. Using the datalink models allows precise data to be sent to a computer. Race times are displayed to 1/10 000th of a second, as is the time between the first and second car. You can check out the latest specification at www.cooksprojects.com. — CooksProjects
  • Great! I just saw the new version on insta! — Bavarian_Diecast_Racing
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