Device with precision frequency stabilized audible alarm circuit

A device comprising:

• an electroacoustic transducer;
• driver circuitry coupled to the transducer, the driver circuitry operative to drive operation of the transducer;
• control circuitry coupled to the driver circuitry, the control circuitry operative to provide a signal that can vary output of the driver circuitry;
• a microphone;
• sense circuitry coupled to the control circuitry and the microphone, the sense circuitry operative to:
• monitor an output of the microphone;
• and
• instruct the control circuitry to change a value of its adjustable network based on the monitored output of the microphone such that the transducer emits an audio signal having at least a minimum magnitude, wherein the transducer is coupled to the control circuitry, and wherein the sense circuitry permanently configures the adjustable network to be used as a phase shift network that supplements a phase of the transducer to enable stable operation of the transducer.