is to provide a means of rapidly discharging variable capacitor c12 via resistor r32 in order that the range and then the dwell settings may be read one after the other without an undue delay as c12 discharges to a zero volts starting point this method provides an economical means of reading manual settings with a relatively high resolution of typically as high as from 1 part in 16 to 1 part in 128 as may be required to properly control aspects of circuit operation means are provided for facilitating manufacturing testing via connection points labeled enable test mode and serial output this feature provides for an economical way to test and debug sensors in production by providing a means of enabling a software routine within the sensor to communicate to a computer over a wired connection the contents of the microcontroller 39 s internal memory registers as a means of discerning aspects of the circuit 39 s operation that would be useful in quickly determining the nature of manufacturing defects that may be present as well as implementing automated manufacturing processes and methods referring to the l e d driver circuitry see fig2 means are provided to decouple high current pulses provided to led2 and led3 comprising r13 and c13 means are also provided to regulate the current supplied.