DEVELOPMENT OF A TIME EVENT MARKER FOR A MINIATURIZED RECORDING SYSTEM

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-03424A000400040011-3
• Release Decision: RIPPUB
• Original Classification: K
• Document Page Count: 17
• Document Creation Date: December 27, 2016
• Document Release Date: April 28, 2014
• Sequence Number: 11
• Publication Date: April 15, 1958
• Content Type: REPORT

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DWISLOPMENT OF A
TIME EVENT MARKER FOR A
MINIATURIZED RECORDING SYSTEM
April 159 1958
Table of Contents
Paragraph No.
EgfalLkts
1.0
Introduction
2
2.0
Difficulties Encountered with Original Model
3.0
Parameter Changes in Revised Model
2
4.0
Power Consumption Investigation
6
5.0
Areas Requiring Further Investigation
9
`4.
�1--
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1.0 INTRODUCTION
A
This report covers the status of work on Project No. 74Ato April 15, 1958.
1.1 Ninety percent of the applied effort has been directed to Project
No. 74A, TEM, with Project No. 74B, SAD,, receiving secondary
consideration.
2.0 DIFFICULTIES ENCOUNLhaED WITH TWE ORIGINAL MODEL
This model, completed at the time of submission of the February 15th
report, was inadequate as follows: Operating voltage for the unit was
nine volts, due to factors outlined in Paragraph 4.5 of the February 15th
report. Also, failure of the calendar and sweep to operate reliably at
low temperatures (-30 degrees F) was observed after submission of the
last report.
2.1
Oonclusion
were
the use of
required. To
jeweled ratchet
To reduce operating voltage, new solenoids
improve low temperature performance,
shaft bearings and lubrication with
oil was specified.
SI-AT
2.2
Course of Action
The installation of new solenoiderentailed making a new center
plate, since these solenoids are longer than those on the original
unit, (See Paragraph 4.5.3 of the last report), and as a consequence,
extended over the edge of the old center plate. In view of the
major changes required, it was decided (with prior verbal approval
from the Technical Monitor) to fabricate a revised model including
the changes above as well as several additional refinements.
3.0 PARAMETER CHANGES IN REVISED MODEL
3.1 Solenoids
The new solenoids were built and installed on the new center plate.
The solenoid overhang was corrected by extending the new plate
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width .025 inches, and by moving the solenoid .04o inches closer
to the ratchet wheel. This latter was accomplished by shortening
the solenoid drive spring by .040 inches. The drive spring thick-
ness was also increased 25%, giving an overall stiffness increase
of 300%. It is felt that this will yield more positive and uni-
form drive action over a wider range of supply voltage, there
being more impact energy consumed in the drive spring without
undue flexure. The solenoids themselves incorporate these changes:
(a) material changed from 24.750 steel to relay steel #5, giving
higher saturation flux density: (b) thickness of housing doubled
at top, to decrease top gap reluctance: (c) coils wound with #41
AWG HS1 wire (instead of #42) to reduce the ampere turns per
volt requirements and thus permit six volts operation of the
unit.
3.2 Capacitors
The new solenoids have lower inductance since there are fewer
turns. Whereas the #42 wire gave inductances of 750 mh average,
the +41 wire yields inductances which are less by the ratio of
turns, or 68o mh average. The critical capacitance required
is 41,, which previously was 70 mf. A value of 120 mf was used
R2
(See Paragraph 4.3, last report). For the new solenoids, Ccritical
= 106 mf, (R = 160 Since at -30 degrees F, coil resistance
is 25% lower than at room temperature, Cc increases by 60% at
-30 degrees F. So 106 4 .6 (106) . 170 mf, the value of capacitance
required to maintain operation at or above critical at all operating
temperatures. As a result, the value of capacitance used was
raised to 180 mf for 2CR and 3CR. The value used with 1CR was
unaltered, however, because this solenoid, having a lighter contact
*See electro-mechanical schematic, enclosure D and wiring
diagram, enclosure E.
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finger load, operates satisfactorily at -30 degrees F (although
oscillation in the current pulse is evident), and any increase
in the value of capacitance here would increase the chance of
double operation of 1CR around a sweep oteration at the higher
operating temperatures.
3.3 Bearings and Lubricants
Jeweled bearings were installed at the lower ratchet wheel pivots
and all bearing surfaces (including watch bearings) were lubricated
with
oil, in an attempt to improve low temperature operation.
This oil has relatively low viscosity at low temperature.
3.4 Difficulties Encountered in Fabrication
The new solenoids were copper and nickel-flashed all over, then
the plunger working face was plated with 1 mil of copper to prevent
the plunger from sticking closed due to residual pull. Finally,
nickel flash was applied to the working face. The plating,. however,
began peeling, and considerable investigation was necessary before
a correct procedure was obtained, namely, thorough pickling of
the #5 relay steel was required before Plating. The parts were
then re-plated satisfactorily.
3.5 Summary of Performance revised model
a. The engineering model delivered to the monitor on Friday;
April 4, 1958 satisfactorily demonstrates the feasibility
of this system. There are areas of doubtful reliability,
mainly at low temperatures, clue to increased mechanical
loading on the solenoids. This problem was not wholly
eliminated by the change outlined in Paragraph 3.3 of
this report, but the cause of the difficulty (relative
expansion between plunger and closely fitted sleeve with
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resultant binding) has been determined and corrective action
(to increase the sleeve and plunger fit tolerance) will be
taken.
b. Internretation of Solenoid Current Pulse
2nc1osure (A) shows photo-oscillograms of the input current
to 1CR alone, to ICR and 2CR, and finally to 1CR, 2CR, and
3CR. Each pulse has two dips during the first 15 milliseconds
of conduction, points marked,a and b. Point a represents
plunger slowdown at incipient disc motion; point b represents
plunger air gap closure. Solenoids 2CR and 3CR start to pass
current (point c) before the energizing solenoid (1CR and
2CR, respectively) completes its stroke. This is because
the control circuit disc contacts move onto the make position
and then continue to move until centered on this position
at plunger closure. The "steps" in the pulses beyond 60
milliseconds represent the plunger dropout points_ (Point d).
(It should be noted that both the time and current scales for
1CR pulse alone are magnified.)
3.5.1 The basic current pulse (the pule unmodified by points
a, b, c, and d discussed above) shown in enclosure A,
is closely represented by the equation t :=
when critically damped, i.e., when C e 4L Here 11E14
equals applied voltage, "L" is the solenoid inductance
in henries, lit" the time in seconds from switch closure
(t=o), "C" the base of napierian logarithms, and "a" is
(where "RI' is the solenoid resistance in ohms).
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The total energy input to one pulse, then, equals
0
co
E- --
6
4-
3.5.2 When the circuit is overdamped (above critical), the
current equation becomes
I;
-
(-4z+b)L.
LC
3.5.3 When the circuit is underdamped (below critical, or
oscillatory), the current equation becomes
6.-
-----, 64;
/.74, a .....
ic
,_.�.
Energy relations have not, as of the time of writing
this report, been calculated for the latter two cases,
thus the assumptions appearing in Paragraph 4.1 and
discussed in Paragranh h.2 below.
4.0 POWER AND NiNISHGY CONSUMPTION, REVISED MODEL
A study to determine power and energy requirements of the unit has
been completed. Although peak instantaneous Power is not of prime
importance, peak instantaneous current is. This peak current (70 ma)
occurs when 1CR, 2CR, and 3CR operate simultaneously (i.e., when all
three discs index), and is nearly equaled by the current drain when
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TEM sweep is onerated (60 ma), although in the latter case the current
drain is present for 1.2 seconds total duration, while in the former,
the peak drain occurs for only several milliseconds. At any rate, the
voltage source should be able to handle 70 ma continuous drain with no
more than 5% fall off in terminal voltage.
4.1 Method of Calculation of Energy Consumed
Solenoids 1CR, 2CR,,and 3CR consume energy (during each pulse
operation) which is given by the equation ENERGY ( 21, 2
.....
R JR
where the energy appears in coil heating, magnetization of the
iron, and mechanical work; capacitors Cl, C2 and C3 store an
equal amount of energy during each pulse (which is later dissipated
in the shunt resistors 121, R2 and 113), so the total energy input
during each pulse is 2- (i9-619 watt seconds. This is the
transient energy. Following the pulse, each solenoid circuit
remains closed for a certain length of time, depending on the
solenoid in question. During this latter period, energy is
consumed by the shunt resistor R1, R2 and R3 in parallel with
the internal cepacitor shunt resistance, Rs, and is the "steady
state" energy. The sum of transient energy and steady state
energy gives the total energy consumed for a solenoid per operation.
If this is multiplied by the known number of operations per sixty
days, the total energy input is obtained. This energy, divided
by the applied voltage E, yields the 6o day ampere-hour require-
ments for the solenoid.
For the sweep, the energy required by relay ST2 per sweep operation
is E2 times the duration of the weep (2.4 aeconds). This times
Tr
an assumed 1440 sweep operations per 6o days gives total energy
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to 122, which when divided by E, gives total ampere-hour require-
ments for 3T2. Similarly, the 10/sec0 multivibrator requirement
Per sweep operation = multiplied by the time of operation,
'Leer
plus IE multiplied by the "rest" time, where the �first term
represents energy taken by the sweep during the "working" half
cycle times the number of these cycles, so time of operation
equals. 1.2 seconds, or half the sweep duration. The last term
represents energy taken by the multivibrator during the"rest"
half cycle, multiplied by the number of these cycles, so "rest"
time equals 1.2 seconds also, since the MV "on" and "off" times
are equal. Now represents the current drawn by the MV during
"rest" time, and equals 2 milliamps. This energy multiplied by
1440, gives total energy input to the 10/sec. MV and to SCR during
a 60 day period, which when divided by E (applied voltage) gives
ampere-hour requirement for the sweep.
4.2 Total Milli-ampere-ffour. Requirements, revised model
Using the settled outlined in Paragraph 4.1 above, the following
calculationa and values are obtained (see enclosure B). It should
be pointed out that the values of transient energy for 2CR and 3aa
are on the low side, since these solenoids (having more series
capacitance) are operating above critical, and therefore, the
equation e.(U, E2
for energy is low. This is at least
R R
partially compensated, however, by the fact that the steady state
energy is large, being summed over the entire control circuit
closure cycle. The large ampere-hour requirement of ST2 can be
reduced by the addition of an RC circuit to reduce hold-in current.
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In conclusion, the values given in enclosure B are approximate
in view of the foregoing in addition to possible parameter
variations in the actual installation. A value of 160 MA-Hr.
as a total possible maximum figure should be adopted.
5.0 AREAS REQUIRING FURTHER INVESTIGATION
The following improvements are being considered to (1) increase relia-
bility in present model over a wide temrerature range, (2) decrease
the difficulty of assembly and adjustment of the unit, while increasing
the precision of adjustment.
5.1 10/sec. Multivibrator
This packaged unit, at present, has no provision for adjustment
of frequency. Furthermore, frequency varies 3% over the applied
voltage range 5.5V to 6.5V and 3% over the temperature range
70 degrees F to -30 degrees F. Since this variation is inverse
with both temperature and voltage, this effect is intensified by
the fact that in general, battery voltage itself falls off with
low temperature. As a result, a MV having more refinedchara0-
teristics is desired, particularly in regard to provision for
vernier frequency adjustment. Such a unit is on order for T.
5.2 Solenoid Design and Calendar Ratchet Design
Several refinements are in the offing here. A solenoid reversal,
where the return spring drives the load, is being considered,
because (a) less kinetic energy is delivered to the disc and
ratchet assembly during drive, and (b) the ratchet and disc
is always locked by the action of the ratchet wheel and stop
pin against the drive spring. Thus, when not indexing, the disc
cannot be moved in either direction.
�9�
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Recent work indicates the solenoid itself may deliver more energy
per watt-second input if one or two changes are made in the coil
and plunger configuration. In this regard, more clearance between
plumgrr and sleeve is also desired, to improve low temperature
performance. (See Paragraph 3.5 a.)
5.3 Printed Circuit Plate
This plate gave considerable installation difficulty, as outlined
in Paragraph 5.3 and 5.3.1 of the February 15th report. At this
time, a new printed circuit plate has been received which "sandwiches"
the printed circuitry (found on the bottom side of the old plate)
between the top printed circuit plate and a flat plastic bottom
plate. This new plate should be more readily mounted, as a result.
Complete tests, however, are not available as yet.
5.4 Sweep Drive Design
The overtravel and eccentricity associated with the gearing system
presently in use, may be eliminated by (a) driving the bridge
directly with a long-stroke solenoid, (b) incorporating a positive
detent into the bridge drive wheel to prevent overtravel. This
problem is under investigation. A solenoid reversal, as outlined
in Paragraph 5.2 above, may also be beneficial here.
5.5 Method of Winding Time Base
A solenoid powered winding mechanism has been considered to replace
the negator mainspring. This system would require leas space '
physically, but, of course; increases MA-HR battery requirements
somewhat. One development considered uses a standard watch move-
ment wound by a short stroke solenoid operating a ratchet on the
center wheel, pulsed through contacts similar to the once/min,
contacts of TEM time base.
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�
5.6 Once/min, Watch Contacts
Use of the watch outlined in 5.5 wound by a short stroke solenoid,
would allow replacement of both the TEM once/min. contact and the
watch wind contact by a commutator-tyPe contact ring, against which
fingers ride in a manner similar to TEM Sweep. These fingers are
attached to a shaft of the watch, which makes one revolution per
minute. Thus, a bridge attached to this shaft and carrying contact
fingers, can perform several switching operations analagous to
those performed by the calendar printed circuit discs. This system,
then, would eliminate the present contacts and replace them with
moving fingers upon a divided stationary disc, yielding, in general,
more reliable operation and more uniform make and break characteristics.
Some work has been done along this line.
5.7 Method of Supplying Current Pulse to Solenoids
Also under consideration is the use of a circuit modification to
preclude the relatively large instantaneous battery drains outlined
in Paragraph 4.0 of this report. This amounts to an electrical
'reversal," wherein instead of supplying heavy peak-drains over a
short period of time, the battery would supply light drains over
long periods of time to charge the capacitor. When the control
circuit closes, the charged capacitor would rapidly pour its charge
into the solenoids, following which the small capacitor charging
current would again build up capacitor charge through the battery.
Work is being done to determine the relative value of this method
compared to that presently in use, when small electromotive cells
are employed as the source voltage. It is with small cells (incapable
of handling large instantaneous currents) that this circuit would
show possible superiority. (See Enclosure C for circuitry comparison)
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5.7.1 This proposed circuit has the inherent disadvantage that
R1, being in series with the capacitor shunt resistance
Rs, and comparable in value, acts as a voltage divider so
that el will not charge to the full value of E (according
to the ratio 5 30 If 111 is thus limited in value,
however, the leakace current, after C1 is essentially fully
charged, cannot be reduced to negligible value, thus a
4/15/58
"standby" energy term apoears. If R1 is increased in value
to reduce this "standby" energy, a higher value of E is
needed to supply like amounts of charge to 01.
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MILLIAP1Pt
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20 40 GO 80 100
TIME IN miLu5EcoN15
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CALMATION OF TOTAL AMPERE HOUR REQUIRE= oF�.T111, PROJECT 714A,
OVER A SIXTY DAY OPERATING PERIOD
1CR: Transient Energy (per operation)
where E = 6v
L = .680h
R = 160 -it-
Steady State energy (per operation)
where Ri = t1 . 3 sec
Rs = 2 A
Total Energy Consumed, 60 day period
2L
R ) X 2
= 3.82 M-d3
2 -
= E tl
R1 RS
R1 RS
= 1.14 MWS
- 4.96 x 86.4 x lo3
- L.28 I 105 14WS
Ampere Hours required = 4,23 X 105 = 119.8 MA-HR I
x 36 x-io3
2CR: Transient Energy (per operation) = 3.82 MWS
Steady State energy (per operation) = E2 t2 6.24 YMS
R2 Rs
Rs
. R2 1.5 m t2 = .120 sec
Rs = 1.'13 1.1
Total Energy consumed, 60 days = 10.06 X 8.64 x 103
. .866 x lo5 mws
AmpereRours Required = .366 x
6 X 3.6 X 103
3CR: Trent Energy. . 3.82 NS
3.0. EnerEy =
-
3 as
R3 + Rs
4.011:K-fad
t3 = 1200 �see.
= M
R, = 1.33 m
S. S. Energy = .L
Total Energy, 60 days, = 3302 X. 36 = 3.29 X 103 MWS .
reauired 3 I.3S:3 = F.152 M1,-HR 1
703 "--
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24.0 MA-TIMJ
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-2-
TOTAL CALENDAR AMPERE HOUR REQ. 0
SCR:
Energy per Operation
t,
E2
E
R.
61T
160
R
L_
Energy per 1440 operations
Ampere Hour requirement
T � ergy per Operations
2�
=
.
=
=
284 1418
t =
=
1
1.2 sec
2 iriA.
sea
1)0t0 X 284
x 103
1406 X 103
18.9'MA-1M
6 x 3.6 x ao)
E2
t = 2.4
E 617
= 431 PG�IS
Energy per 11140 Operations =, 431 X 1440
. 629 x 10 MWS
Ampere Hours Required = 620 X,103
6 x 3.6 x lo3
TOTAL SWEEP AMPERE HOUR REQ.
TOTAL TM (74) AMPERE HOUR REQ. ={2 MA-BR I
4/2/58
-R = 200
37.3 10.1A.-HR
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