Designed a fully functional metal detector from scratch using mosfets configured into oscillators, amplifiers, mixers, and current mirrors. Used simulation and calculation to find components that would work, and tuned the device to detect metal up to 120mm away. This project was part of the Fundamentals of Solid State Circuits Course.
I designed the PCB in Altium designer, keeping each stage of the device in its own room, adding test points in easy to reach places, and kept the amount of layers down to 2 through planning and some creative wiring.
I created a full LT Spice simulation of the metal detector to optimize values for many RC components. Using time step and frequency step analysis, was able to tune many of the components while waiting for PCB to print.
I used the Oscilloscope to test and tune each stage of the PCB. This screenshot is from the final output stage (speaker) when there is metal on the coil.
I used Altium's 3D rendering to make sure that none of the large components would hit each other. In hindsight, I should have spaced some of the ICs farther from each other for easier replacement / debugging.