Some electronic switching circuits

Referring to the letter to the editor by H. A. Brown and P. W. Ryburn, published on page 36 of the August 1938 issue of Electrical Engineering and to the last paragraph of my article “Some electronic switching circuits” on page 211 in the May 1938 issue, I would like to point out that this paragraph states that the minimum RiCs product rather than the minimum impulse interval would be 0.25 microsecond. There is considerable difference in meaning because the time constant, as Brown and Ryburn are aware, gives the time only for the interval during which the voltage across the condenser Cs has dropped to about 37 per cent of its peak value. The impulsing interval, while dependent on the time constant, will be much greater since the voltage must drop approximately exponentially below the deionizing potential of the type-885 tube before the 885 will stop conducting and the cycle can be repeated.