When I designed the system, wiring the laser modules to the Arduino for power seemed like the simplest solution, in practice, this results in long cable runs that get in the way. There is no need to power the laser modules from the Arduino, they could be battery powered and simply switched on when needed.I will probably create a version 2.0 of this system as there are some obvious improvements that could be made: Press the reset button to time another run.The time in milliseconds is then displayed on the screen.The system will stop once the second laser beam is broken.The system will start timing once the first laser beam is broken.Align the lasers so that they shine directly on the LDR sensor.Press the select button to initialise the system.You should now be ready to use the system! The images show the stages of operation. the actual cost of the electronics is only £22 so there is probably room for a lot of optimisation here. Most of the cost here is for cases, nuts and bolts, etc. Total cost was around £55, this assumes access to both a laser cutter and 3D printer. 4 x 3D printed enclosures - Material cost was around £5.Plastic PCD standoffs - Kits of these can be had for quite cheap on Ebay.- £6.80.4x 1/4 inch nut - To fit a standard tripod thread - £2.Make sure the power of the laser is not greater than 5mW. 2 x Laser module - Searching ebay for "arduino laser" should show plenty of options.2 x Light Dependent Resistor (LDR) module - Searching ebay for "arduino LDR" should show plenty of options - £2.30 each.LCD keypad shield - Ensure this is made to fit the version of the arduino you have - £5.Adafruit feather wing protoboard - A small section of any type of protoboard is also fine - £1.Arduino R3 (or compatible board) - £4.50.
#Cheap fat timing solutions code#
Implementation of the circuit and code is at your own risk. I have plans to release both a version 2 and version 3 of this system with improvements, please see the last step of the instructable. This project was initially put together on a very tight deadline and worked absolutely fine for the purpose intended. I'm aware some things could be a lot better or more efficient. This type of system is great for STEM activities and can be used to measure how fast things like rubber band cars, mousetrap cars or pinewood derby cars travel a set distance.ĭisclaimer: The solution presented here is far from optimal. The resulting recorded time is displayed on the LCD screen.īuilding a system such as this with students is a great introduction to coding, it is also a really useful classroom resource once it is finished. Using two of these gates the system starts the timer when the first beam is broken and stops the timer when it senses the second beam has been broken. By measuring the output of the LDR, the system can detect when the laser beam has been broken. Each light gate consists of a laser module at one side, this projects a laser spot onto a light-dependent resistor module (LDR) at the other side. The operation of a light gate timing system is pretty simple. It turned out that pre-built light gate timing systems are actually quite expensive though, so I decided to build my own. Initially, I thought I would buy a cheap ready-made system from eBay or Aliexpress, these systems are commonly known as light gates, photo gates or similar. As part of my teaching, I needed a system to accurately measure how quickly a model vehicle travelled 10 meters.