Jeremy Gilbert made an awesome clicky toy. The goal of the project was to create a toy that is fun to use, be tactile, light up, and make fun and satisfying noises.
After looking at different options to get the right “clicky-ness”, a 5V relay was used. Jeremy discovered that you get get louder clicks if you overdrive the voltage. While this probably isn’t so good for the relay, he felt that since the actual duty cycle is so short it was worth the risk.
The clicky box of awesomeness is field programmable so that when new suggestions come up during user acceptance testing (performed by his 3-year old daughter) they can be implemented right away.
The write up on Jeremy’s Hackaday project offers a good narrative of how he approached the challenge of getting the right clicky sound and feel.
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.