Oscillator CircuitsAn oscillator circuit is capable of generating an electrical signal that varies sinusoidally in amplitude when connected to a DC voltage source.
The frequency of the generated signal is determined by a combination capacitors and inductors which are arranged in a loop configuration. This loop is known as the "tank". The tank is the heart of the circuit, responsible for generating oscillations. Other components of the oscillator circuit are responsible for maintaining and stabalizing oscillation. The Sleep Sound team has chosen to work with an oscillator circuit for its ability to generate signals of different frequency when faced with changing component values within the tank. More specifically, a Colpitts oscillator was chosen for its' requirement of one inductor within the tank. By building a variable inductor into an infant sleepwear shirt and connecting it to the tank of the oscillator, chest movement due to breathing can be effectively translated to a sinusoidally changing frequency. The following figure shows a schematic of our current oscillator circuit. 
The circled area denotes an additional branch of the circuit that was added by the team to increase stability in the output signal. For our purposes, this circuit will be denoted as the tuneable oscillator. | 