Fortress Technologies An E1T Timepiece, Руководство пользователя

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If t
2
is the total time taken for the potential across the capacitance C to reach the value V
a2
(0) from
an initial value of zero,
Dividing (2) by (1):
In this equation (t
2
—t
1
) is equal to the time taken for the beam to move from position 'nine' to the
`zero' position. Let (t
2
- t
1
) = T
Putting the values quoted above into this equation:-
When this equation is solved for T, it is found to be about 20.68 μ sec. This is the minimum
possible resetting time. In actual practice the resetting pulse should be somewhat longer than
this in order to allow an adequate margin of safety. If an allowance of 33 μ sec is made for the
resetting time, the maximum counting rate which can be attained is about 30,000 per second. It is
found in actual practice that E1T circuits can operate reliably at up to 30,000 pulses per second
when the resulting operation is carried out by cutting off the electron beam in the tube in the
type of circuit shown in Fig. 5.10. In practical circuits the stray capacitance C should be kept as
low as possible.
Page 119 Version 1.0 Copyright Grahame Marsh/Nick Stock 2019
V
b
− V
a 2
(0)
V
= e
− t
2
Ra
2
C
V
b
− V
a 2
(0)
V
b
− V
a 2
(9)
= e
− t
2
− t
1
Ra
2
C
V
b
− V
a 2
(0)
V
b
− V
a 2
(9)
= e
− T
Ra
2
C
300 − 240
300 − 95
= e
− T
1.02 × 106 × 16.5 × 1012
Fig 5.10 - An E1T Counting and Reset Circuit for Operation at Frequencies up to 30 kc/s