Patent ID: 8736456

Claim:
A method for detecting the presence of a gas and measuring a concentration of the gas in an environment, the method comprising the steps of: sensing the presence of the gas and generating an analog sensor output based on a concentration of the gas in the environment; processing the analog sensor output through an audio circuitry to generate therefrom an audible tick having a frequency in proportion to the analog sensor output, the processing step comprising: amplifying the analog sensor output with a summing amplifier to generate an amplified analog output; producing an oscillating analog output based on the amplified analog output; converting the oscillating analog output to a pulsed output whose pulse rate is in proportion to the gas concentration sensed by the sensing means; emitting the audible tick based on the pulsed output; producing a digital output with a microprocessor based on the oscillating analog output; converting the digital output to an analog control loop signal; delivering the analog control loop signal to the summing amplifier; and adjusting the digital output of the microprocessor to selectively increase and decrease the frequency of the audible tick.