Tick from our MicroKits Theremin Kit is a type of integrated circuit known as a 555. The 555 IC is like an adjustable clock. By combining the 555 with a few external parts, we can create a circuit that switches between a low and high output. Connecting different resistors and capacitors changes how quickly the clock ticks. That’s why we’ve given this chip the nickname “Tick” in our kits!
Tick is technically a “556” timer, which just means they have two 555 timers built in, one on each side. 555 timer chips can be used in many different kinds of circuits. You can read the 555's datasheet by clicking here: https://www.ti.com/lit/ds/symlink/tlc556m.pdf.
555 timers work using the principle of resistor-capacitor charging, often called RC charging. If you charge up a capacitor through a resistor, current will be restricted, and the capacitor will charge in a slow, predictable way.
555 timers constantly charge and discharge a capacitor through a resistor. The larger the capacitor or resistor, the longer it will take the timer to complete a cycle.
When you move your hand towards a MicroKits theremin, you increase capacitance and increase the time it takes Tick to create an electrical pulse. The higher the capacitance, the fewer pulses happen every second. Tick converts capacitance into a useful signal that Micro, the other chip in our theremin kit, can process.