Juan - The Laser Tachometer
Task: Design and construct a three-function zero-friction tachometer from only basic electronic components for under $150
Juan was a laser tachometer created by myself, Gabriel Wong, Soheil Koushan, and Mahan Nekoui for our AP Physics end of term project. Juan is only made from IC's and basic electronic components and has three display options: revolutions per second, revolutions per minute and total revolutions of a spinning disk. We won the Best Project award for having the only soldered device that exceeded all project criterias. This demonstrates my knowledge of electronics, a skill every mechanical engineer should have but many do not.
Project objectives:
1. Modular
2. Functional
In addition to making a functional device to satisfy project criteria, we wanted to make the device modular so components could be tested in modules.
The final product features a clean, modular device with removable jacks, barrel plug, and functional on-off switch.
I was primarily in charge of designing the device setup (see CAD drawing below) and fabricating the device. I performed majority of the soldering based on schematics provided by Gabriel.
The proposal can be found here and the operations manual can be found here.
Technical specifications:
Input Voltage 5 V DC
Max Current 2 A
Laser Safety Classification Class II
Laser Wavelength 630-680 nm
Maximum Count 999.9 revolutions
Maximum RPS 999.9 RPS
Maximum RPM 998.4 RPM
Count Accuracy ±.1 revolutions
RPS Accuracy ±.1 RPS
RPM Accuracy ±1.6 RPM
Delay Between RPS Update 1 s
Delay between RPM Update 3.75 s