The project came about when he needed to test the top speed of a stepper motor. After putting it together the project became an important diagnostic tool for a larger project – not only does it test the top speed of stepper motors but it also works as a tool to verify code.
The tachometer measures rotational speed using only simple light sensor with an op-amp comparator circuit. While many mechanical engineers might cringe at the thought of an op-amp, Elliot’s team found a tutorial that explained them well.
The project came about when he was having difficulty getting an expensive input board to work in a haunted house attraction. When he discovered that the iCade keyboard commands worked over a USB connection, he figured he could use an Arduio board and hood the USB side to an iPad and create his own interface. With a bit of research he got his project up and running.
While he used genuine arcade joysticks and a vintage CRT display, it was still lacking in authenticity. The risk of a $0.25 loss was missing. Since emulators basically allow unlimited lives, taking away the gamble of a valuable coin, David disabled that feature and created a little challenge that must be won to add more coins/lives.
The code and many other details about the project (like how to obtain the valuable game play credits) are available on GitHub.