close

Вход

Забыли?

вход по аккаунту

?

код для вставки
Nov. 26, 1946.
2m @,598
J. _P. SMITH
KEYING CIRCUI T
Firled JAanQ 22, 1943
a
n@M/
W.
¿wmw@00«œwfc
WM
Mw.if
i.
l/ .
»a
_áâN/
f
.
6,6/0 VaL M65 aF» M552'
îit
Í
ßnventot
ACîttorneg
Patented Nov. 26, 1946
*fi‘UNlrED STATES >PATENT orifice
'
2,411,598
KEYING cmcm'r' »
John P. Smith, Cranbury, N. J., assigner to Radio
Corporation of America, a corporation of Dela
Ware
Application January 22, 1943, Serial No. 473,259
s anims. (c1. 25o-27)
1
My invention relates to keying or switching cir
cuitsV and particularly to an electrical circuit
wherein electrical pulses are produced under the
control of mechanical switching.
.
2
Tube IS has a grid resistor RI and a grid ca-v
pacitor Ci having comparatively large resist
ance and/or capacity, respectively, whereby the
time constant of the circuit RI-CI is com
One object of the invention is to provide an 5 paratively large. Thetube ZI has a grid leak
improved means for obtaining short electrical
resistor R2 and a grid capacitor C2 having com
Another object of the invention is to provide
paratively small values so-that the time constant
of circuit R2-C2 is comparatively small. The
cathode end of resistor R2 may be connected to
an improved means for obtaining electrical
a variable tap 28 on a source of positive biasing
pulses which occur synchronously with the rota
voltage for controlling the width of the multi
vibrator pulses. A bypass capacitor 29 may be
provided.
The cathode circuit of the tube I9 includes the
pulses in response to the actuation of a me
chanical switch.
tion or other motion of a mechanical element.
>-In a preferred embodiment of the invention,
I utilize an asymmetrical multivibrator and con
nect the mechanical switch in the cathode cir 15 switch i3 so that the cathode of tube I9 is con
cuit of the multivibrator tube that has the longer
grid capacitor-grid leak resistor time constant.
A short electrical pulse is generated in response
to closing the cathode circuit by the switch, the
nected to ground through the conductors 3l and
32 and the switch I3 when the switch I3 is closed.
When switch I3 is closed, plate current flows
through tube i9 to cause a voltage pulse 35 of
pulse ending before the switch is opened. Also, 20 short duration to appear on the plate of tube
2I. The action of the circuit in producing the
the longer time constant is adjusted so that the
grid capacitor of said tube is substantially fully
desired short pulse is illustrated by the graph
in Fig. 2 showing the voltage on the grid of tube
discharged before the switch is again closed.
2l and by the diagram in Fig. 3 showing the dif
'I'he invention will be better understood from
the following description taken in connection 25 ferent time relations. The action is substantially
as follows: When the switch I3 closes there is
with the accompanying drawing in which
an increase of current flow through the tube I9
Figure 1 is a circuit diagram illustrating one
which causes its plate to go more negative and
embodiment of the invention,
drive the grid of tube 2| more negative. This
Figure 2 is a graph that is referred to in ex
30 decreases the plate current through tube ZI to
plaining the operation of Fig. 1,
make its plate more positive whereby the grid
Figure 3 is a graph showing the time relations
of tube I 9 is made more positive, thus further
between the switch operation and the multi
increasing the current flow in tube I9 and rein
vibrator output, and
'
`
forcing the negative charge on grid capacitor C2.
Figure 4 is a graph illustrating another method
35 As a result, the tube ZI is almost instantly driven
of practicing the invention.
to plate current cutoff to produce the front edge
In Fig. l, one embodiment of the invention is
of the short pulse 3S. This cutoiî condition is
shown applied to a system wherein a directional
held until the charge of the capacitor C2 leaks
antenna I0 is rotated about a vertical shaft or
oif through resistor R2 enough to let the grid of
axis I I at a constant speed. It is desired to pro
duce a, short electrical pulse each time the an 40 tube 2! go positive. The plate of tube ZI now
goes negative, whereby the capacitor CI is
tenna I0 reaches a certain position, for example,
charged to block the tube I9, thus producing the
each time the antenna radiation pattern is point
back edge of the said short pulse 36. Because of
ing north.
the comparatively long time constant of the cir
A switch i3 located near the antenna Il) is
closed periodically by a cam I4 'as the antenna is 45 cuit Ci--Ri, the tube I9 remains blocked for a
comparatively long period and as a result the in
rotated. The cam I4 may be mechanically cou
terval between the successive short pulses is long
pled to the shaft II as indicated by the broken
compared to the width or duration of these pulses.
line I6 sc that the switch I3 closes once for each
The width of the pulses 3S may be controlled
rotation of the antenna.
A multivibrator I8, which may be located at a 50 by adjusting the tap 28 to change the positive
bias on the grid of tube ZI, this bias adjustment
point remote from the antenna Ill, comprises two
having the same effect as changing the values
three-element vacuum tubes I9 and 2|. Plate
of the elements C2 and R2. In one specific em
voltage is applied to the tubes through plate re
bodiment of the invention the circuit time con
sistors 22 and 23. The resistor 24 and capacitor
55 stants and the bias for tube 2| were so adjusted
26 are ñlter elements.
2,411,598
4
3
tube> to break the flow of plate current there
that the short pulse was approximately 1/20 sec
onds long while the time for complete discharge
through when the switch is open, and means for
of the capacitor CI was three and one-half sec
periodically closing said switch for a length of
time that exceeds the duration of the shorter
ends, this being the condition illustrated in Figs.
2 and 3.
As indicated in Fig. 3, the capacitor CI issub
duration voltage pulses produced at the plate of
said other tube.
2. In combination, an asymmetrical multivi
stantially completely discharged between the
brator comprising a pairof tubes each having a
time the antenna switch I3 opens and the time
it is again closed. In the example illustrated the
cathode circuit, an anode vand a control grid and
switch I3 has an “on” time of one second and a 10 further comprising a -grid capacitor and a grid
leak resistor connected to the control grids of
said tubes, respectively, one of Said tubes having
recurrent closing rate of six seconds.
If desired, the invention may be utilized to pro
vide more than one short pulsefor each actua-`
tion of the mechanical switch. In this case the
a grid capacitor and a grid leak resistor that have
a substantially longer time constant »than thel
grid capacitor and grid leak resistor of the other
tube, a switch connected in the cathode circuit of
said one tube, and means for periodically closing
said switch for a length of time that exceeds the
duration of the shorter duration voltage pulses
20 produced at the plate of >said other tube.
Widths of the short pulses would be determined
by the time constant of the circuit C2-R2 and
the intervals between pulses would be determined
by the time constant of the circuit C I-RI . Thus,
if instead of the arrangement illustrated in Fig. 3,
the switch I3 remains closed for seven seconds,
as indicated in Fig. 4, three short pulses would be
Ygenerated with an accuracy of timing depending
on the multivibrator constants. By reducing the
time constant of the circuit RI-CI the natural
vperiod of the multivibrator may be decreased so 25
`that for seven seconds “on” time for switch I3
more than two short pulses may be generated.
3. In combination, an asymmetrical multivi
brator comprising a pair of tubes each having a
cathode circuit, an anode and a control grid and
further comprising a grid capacitor and a grid
leak resistor connected to the control grids of
said tubes, respectively, one of said tubes having
a grid capacitor and a grid leak resistor that have
a substantially longer time constant than the
grid capacitor and grid leak resistor of the other
1. In combination, an asymmetrical multivi
brator comprising a pair of tubes each having a 30 tube, a switch connected in the cathode circuit
of said one tube, and means for periodically clos
cathode circuit, an anode and a control grid and
further comprising a grid capacitor and a grid
ing said switch for a »length of time that exceeds
the duration of the shorter duration voltage
leak resistor connected to the control grids of saidpulses produced at the plate of said other tube
tubes, respectively, one of said tubes having a
grid capacitor and a grid leak resistor that have
but which is less than the natural period of the
a substantially longer time constant than the
multivibrator.
grid capacitor and grid leak resistor of the other
JOI-IN P. SMITH.
tube, a switch connected in the circuit of said one
I claim as my invention:
y
'
Документ
Категория
Без категории
Просмотров
0
Размер файла
294 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа