of the input capacitor c1 is 0 8 volts the potential at the right side of the input capacitor c1 is 2 millivolts and the charge across the capacitor is the difference between 0 8 volts and 2 millivolts at time t1 when the fixed time interval starts switches s2 and s4 change to an open state and switch s1 closes whereby the potentials at each side of the input capacitor c1 go down by 0 3 volts which is the difference between the voltage levels of the midpoints of the two bridge arm since a negative measurement voltage is applied to the input of the integrator amplifier a1 the output of the integrator amplifier ramps down at time t2 when the fixed time interval ends and the variable time interval begins the input of the integrator amplifier a1 goes up by 0 5 volts which is the difference between the voltage level of the source ea and the voltage level at the junction between the two resistors of the temperature insensitive bridge arm since a positive reference voltage is now applied to the integrator amplifier a1 the output of the integrator amplifier ramps up until it crosses the level of the reference signal at that time the variable time interval ends switches s2 and s4 close and switch s3 opens note that the output of the detector amplifier is at a logical low during the initial time interval changes to a logical high at the start of the fixed time interval and remains at this logical high until the end of the variable time interval when it returns to a logical low the decimal 9 output of the highest order.