Flashlamp operation circuit performing continuous on=off switching - utilises semiconductor switch with photodiode in control circuit monitoring limiting current during discharge of capacitor

摘要

The lamp (5a) is wired in series with an inductor (7) whose stored energy is dissipated in the form of current through a free-wheel diode (8) in parallel with the combination (5a,7). A semiconductor switch (6) is opened on attainment of a limiting current (about 150 A). On reclosure, further triggering (4) of the lamp (5a) is unnecessary because of sufficent residual ionisation. The cycle is continued until the capacitor (2) is discharged. USE/ADVANTAGE - With photographic camera. Short arc lamp having electrodes less than 1 cm apart can be used about 3000 times, dissipating 10 to 20 J per flash.