and d 2 as shown in fig7 b the sense voltage v rs exhibits a flat top on its positive waveform indicating that the waveform is distorted bypass diodes d 1 and d 2 will start to conduct flowing leakage current whenever they are forward biased the peak sense voltage v rs is generally in the range between approximately 1 vpk to approximately 2 vpk it is noted that it is difficult to accurately control the peak current when the value of resistor r 2 is significantly larger than the value of the sense resistor rs current leakage from bypass diodes d 1 and d 2 and resistor r 2 is negligible the voltage v rs on the sense resistor rs reflects the true chopper current as illustrated in fig7 c for example the resistance of the sense resistor rs is 0 8 ohms for an approximate 70 watt hid lamp with an approximate 1 3 ampere starting current and a peak chopper current of approximately 2 amperes based on the formula voltage equals current multiplied by resistance v i r the peak sense voltage v rs is equal to 2 amp 0 8 ohms or 1 6 volts which is larger than the 1 4 volt clamping voltage of the bypass diodes d 1 and d 2 thus the value of resistor r 2 is chosen to be much larger than the sense resistor i e approximately 20 times the sense resistor rs or approximately 15 ohms resistor r 2 also functions as a damping resistor in series with resistor r 1 when the hid lamp is being started ignited resistor r 2 damps a positive portion of the peak resonant voltage when mosfet q 1 is on when resistor r 2 is connected in the.