An auto-synchronlsation system has been developed for the plasmograph which enables the Instrument to be triggered by a pulse derived from the oscillations in the discharge itself rather than from A.C. mains supply.nEssentially, the system consists of a chain of amplifying and differentiating circuits which produces a series of pulses cor¬responding to the beginning of a cycle of "hash". These are fed to a monostable multivibrator, the time constant of which can be va¬ried, Hence probe characteristics can be obtained corresponding to a given delay from the reference time in the cycle.nCalibration circuits have been included in the system which permit the time delay to be measured. Preliminary tests have been carried out on the "hash" in a fluorescent tube excited by a di¬rect voltage. The results show that the system is working satis¬factorily and that it should provide a very useful tool for the study of phenomena of this kind.
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