the pearson–anson effect, discovered in 1922 by stephen oswald pearson and horatio saint george anson, is the phenomenon of an oscillating electric voltage produced by a neon bulb connected across a capacitor, when a direct current is applied through a resistor. this circuit, now called the pearson-anson oscillator, neon lamp oscillator, or sawtooth oscillator, is one of the simplest types of relaxation oscillator. it generates a sawtooth output waveform. it has been used in low frequency applications such as blinking warning lights, stroboscopes, tone generators in electronic organs and other electronic music circuits, and in time bases and deflection circuits of early cathode-ray tube oscilloscopes. since the development of microelectronics, these simple negative resistance oscillators have been superseded in many applications by more flexible semiconductor relaxation oscillators such as the 555 timer ic.