SEQUENCING SYSTEM FOR A BLASTING MACHINE

SEQUENCEUR POUR EXPLOSEUR

English Abstract

ABSTRACT OF THE DISCLOSURE


A sequencing system for a series of control circuits; each
of which has its own control switch. A signal of spaced apart
pulses is communicated simultaneously to all control switches.
Separate normally closed grounding switches are provided for all
but the first of the series of control switches to make them
inoperative. Each control circuit after the first is provided
with a connection which opens its grounding switch in response
to power flowing through the preceeding control circuit of the
series.

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A sequencing circuit comprising: generating means
for generating spaced apart electrical pulses, a plurality of
conductors for communicating electrical energy to respective energy
receiving elements, first means for energizing a first one of said
conductors upon receiving an input signal, second means for ener-
gizing a second one of said conductors upon receiving an input
signal, third means causing sequential electrical pulses of said
generating means to sequentially operate said first and second
means, and switch means which in one position provides an open
circuit between said generating means and said first and second
means while grounding said conductors, and in another position
closes said circuit between said generating means and said first
and second means and opens the circuit between said conductors and
ground.

2. A sequencing circuit comprising: generating means
for generating spaced apart electrical pulses, a plurality of
conductors for communicating electrical energy to respective
energy receiving elements, first means for energizing a first one
of said conductors upon receiving an input signal, second means
for energizing a second one of said conductors upon receiving an
input signal, third means causing sequential electrical pulses of
said generating means to sequentially operate said first and
second means, said first and second means comprising control
switches and a bus which communicates the control terminal of said
control switches to said signal generating means, and said third
means comprising a shorting switch having power terminals and a
control terminal with said power terminals communicating the
control terminal of said second control switch to ground, fourth
means for normally energizing the control terminal of said
shorting switch to actuate said shorting switch, and fifth means

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actuated by a signal from a power terminal of said first control
switch and supplying a signal to the control terminal of said
shorting switch to bias said shorting switch off when said first
control switch is actuated.


3. The sequencing circuit of claim 2 wherein said fifth
means comprises: a signal transfer switch having a control terminal
connected to a power terminal of said first control switch and a
condenser between said control terminal of said signal transfer
switch and ground to delay actuation of said signal transfer
switch until a generally predetermined amount of energy has been
transmitted by said first control switch.


4. The sequencing circuit of claim 3 wherein a power
terminal of said signal transfer switch communicates with said
fourth means to ground out the control element of said shorting
switch and said circuit including another condenser communicating
between ground and the control terminal of said shorting switch to
delay deenergizing said shorting switch even though said signal
transfer switch should be actuated while a pulse to said first
control switch still exists.

5. A sequencing circuit comprising first and second
power distribution circuits each having a normally open control
switch that is closed when its control element is energized, a
signal circuit having parallel branches connected to each control
element of said first and second control switches, a normally
closed shorting switch grounding out said control element of
said second control switch when closed, and signal transfer
means for opening said shorting switch after said first control
switch is closed.

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6. The sequencing circuit of claim 5 including means
for delaying actuation of said signal transfer means for a period
after said first control switch is closed to assure an actuating
power flow in said first power distribution circuit.

7. The sequencing circuit of claim 5 including means
for delivering spaced apart pulses of predetermined duration to
said signal circuit, and means for delaying the signal to said
shorting switch from said signal transfer means until after the
pulse which initiated the action has become inoperative.


8. A cascade system for actuating a first and subse-
quent plurality of power delivery circuits, comprising: first and
subsequent series of electronic power switches in respective power
delivery circuits and each having a control gate which when actuated
closes its power delivery circuit, a signal circuit having branches
each of which is connected to a respective control gate, said
signal circuit being constructed to deliver spaced apart pulses
of predetermined duration to said branch circuits simultaneously,
a series of normal closed grounding switches respective ones of
which are connected to a control gate of a respective one of said
plurality of control gates to normally ground out the signal of
the respective gate without attenuating the signal to said other
branch circuits and first and subsequent series of signal transfer
means the first of which opens the first of said series of
grounding switches when said first power switch is closed, and
the respective ones of said series of transfer means opening a
subsequent one of said grounding switches when a preceding one of
said series of power switches is closed.


9. The cascade system of claim 8 including first and
subsequent series of time delay devices for respective ones of
said first and subsequent series of signal transfer means, each
time delay device delaying actuation of the shorting switch which

19

it controls to assure an actuating power flow in the power des-
tribution circuit from which it receives its signal.
10. The cascade system of claim 8 including first and
subsequent series of time delay devices for respective ones of
said first and subsequent series of signal transfer means for
delaying opening of the grounding switch which it controls until
the pulse to the power switch which controls the respective signal
transfer means has terminated.

Description

3637~

BACKGROUND OF THE INVENIIo
The present invention relates to a sequencing
circuit particularly adapted for use in blasting machines.
This application is a d~visional application of applicant's
application Serial No. 192,277, filed February 12, 1974.
The pr~or art sequential blasting systems have
suffered from the defect of not being able to set off a
plurality of blasting charges at the precise time intervals
of several milliseconds as is necessary to cause ground
shock waves to be in phase. Applicants' Canadian Patent ~-
1,028,20~ issued March 21, 1978, relates to a Blasting
Machine which ~ill energize a plurality of blastlng ~ircuits
at precisely spaced apart time intervals. The present
invention is directed to safety means for preventing
malfunctions Erom energizing the bla~ting circuits pre-
maturely. To this end, the present invent~on provides a
switching arrangement which isolates the triggering pulses
from the electronic switches which cause energiza~ion of
the individual blast~ing circuits. In addition, it i8 a
feature of the present invention to provide additional
switch means for grounding out each of the blasting circults
until such time as the previously described switch means is
closed. In this manner, two levels of safety protection
are provided to make the blasting machine uniquely safe.
The invention relates to a sequencing circ~it
comprising: generating means for generating space~ ap~rt
electrical pulses, a plurality of conductors for communicating
electrical energy to respective ènergy receiving elements,
first means for energizing a first one of the conductors
upon receiving an input signal, second means for energizing
a second one of the conductors upon receiving an inpu~

signal, third means causing sequential electrical pulses
of the generating means to sequentially operate the first


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and second means, and switch means which in one posltLon
provides an open circuit between the generating means
and the first and second means while grounding the
conductors, and in another positlon closes the circuit
between the generating means and the first and second
means and opens ~he circuit between the conductors and
ground.
In another aspect the invention relates to a
sequencing circuit comprising first and second power
distribution circuits each having a normally open control
switch that is closed when its control element is
energi~ed, a signal circuit having parallel branches
connected to each control element of the first and second : ..
control swi~rhes, a normally closed shorting switch
grounding out the control element of the second control
switch when closed, and signal transfer means for opening
the shorting switch after the first control switch is ~ ;
closed~
- The features of the present invention will become
apparent to those skilled in the art to which the invention
relates from ~he following description of the preferred `;
embodiments described with reEerence to the




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accomp.lnying ~rawings forlnil1g a par~ of this specificatlo
ancl in ~l1ich:
~igure l is a schematic wiring diagram of a DC
generator with controlled output voltage and having a
battery power supply, and a pulse generator which produces
pulses of predetermined duration that are spaced apart by
selectable lengths of time; and
Figure 2 is a schematic wiring diagram of one of a
plurality of control circuits each of which are adapted to
discharge a condenser to its output conductor upon receiving
a pulse from the pulse generator, and each of which includes
a grounding switch which normally shorts out the pulse
transmitting circuitry to the following control circuit until
the control circuit in question has discharged its condenser
to its output conductor.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Although the principles of the present invention may
be otherwise embodied, they are herein shown and described as `
: : .
embodied in a blasting machine for setting off a plurality of ~
explosive charges at precisely spaced apart time intervals. ;
In order that the terminology used herein will be clearly
understood, the term "switch" or ~Iswitch means" is used in a
broad sense to indicate any type of electronic apparatus
having a pair of power terminals and a control terminal that
is connected to a control element or gate which when actuated
al~ows energy to flow between the power terminals. Such
switch means will include uni~unction transistors9 transistors, ~ i~
; silicon control rectifiers, etc....................................... `~
Because the blasting machine is to be used in remote
areas, its primary source of power comprises two self-con-
tained 7 l/2 volt batteries BTl and BT2 connected in series,
with the negative terminal of BT2 connected to terminal 3 of 1 ;

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an eight t~rmin~l cclb]e socket Jl, which in ~urn ls
colllmunicate~ l~y line 10 to tcrminal N of cable socket J2,
whicll in turn is grourlded. The posltive ~erminal of ~Tl is
connected ~o a ~use OL-l and then to terminal 1 oE socket Jl ;~
whose correspondi~lg plug Pl is jumpered to pin 2. The
receiving terminal for pin 2 in socket Jl is connected by
line 12 to the normally open mechanical switch SlA of a two
element "Charge" switch Sl. The other terminal of SlA is
connected to junction 14, whose purpose will later be
described, and then to junctions 16 and 18. Junction 16
is connected to a terminal of the "Fire" switch S2A of a
mechanical multiple ganged switch S2 and the other terminal
is connected to the cen~er tap CT of the primary power
winding of a power transformer Xl through resistor R5 and
~unctions 20 and 22. Junction 22 is connected to ground
through condenser C4 to attenuate ripple~ Terminal Cl of
the primary power winding is connected to the collector of
an NPN transistor Ql and the emitter of Ql is connected to
ground. The other terminal C2 of the primary power winding
is connected to the collector of a NPN transistor Q2 whose
emitter is connected to ground. Transistors Ql and Q2 are
matching transistors, and a condenser Cl is connected between
the collectors of the transistors for the usual reasons? as ~-
is understood in the art. The transformer Xl also includes ;-
a center tap control winding, the center tap CT of which is
adapted to be supplied with voltage from the primary power -
supply through junction 18, resistor R3, Zener diode Zl
having a breakdown voltage of 6.8 volts, and junction 24.
Junction 24 is aIso connected to ground through resistor Rl
30 which is adapted to deactivate the control winding when the ,~
power supply is disconnected from the control windingO The
terminal B2 of the control winding is connected to the base




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of tran.si.stor Q2, cm~ h~ t~rm:Ln~:l 131 of the con~rol windLng
i5 conn~cted to L11~ 1)as~ o~ tr~ng:Ls~or Ql. Because of the
slight mismatch due to man~1Eac~ur:lng toler~lnces :Ln trans:istors
Ql ~nd Q2, more current will Elow through one of the trans-
istors than through the other when the power supply is
connected to the transformer, and this will. start the
transistors Ql and Q2 oscillating. The oscillation of the -
primary power winding, will, of course, produce an oscillating
current in the center taped secondary power winding of the
transformer. The center tap of the secondary power winding ~:
is connected to ground 7 and the terminals Al and A2 of the
secondary power winding are connected to diodes Dl and D2,
respectively, to produce full wave rectification. The output .
from diodes Dl and D2 are connected to junction 26, and then
through resistor R2, junction 28, and diode D3 to the high
voltage bus 30. -`.
It is a feature of the present invention that the
blasting machine is capable of properly setting off the . .
charges to which it is connected even though the voltage of
the primary batteries has been depleted to lO volts... The ~ :~
equipment which is connected to the high voltage bus 30 is
all designed to.operate on 90 volts even though the equipment
so far described is capable of producing 120 volts, . ~ ~
It is a further feature of the present invention to i-
prolong the life of the equipment connected to the high :~
voltage bus 30 by shutting off the power supply to the bus 30
whenever the voltage exceeds the nominal 90 volts that is
required to satisfactorily operate the ci.rcuitry connected .i,~
to the high voltage bus 30. The voltage limiting function of ~
the present invention is very efficiently accomplished by the : .
voltage regulating circuitry which will now be described~ ~ :
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The volLa~e re~ulatillg circuitry comprises swltch
Q3 wh:Lch is an NPN transistor, the collector of which is
connected to the pr:imary power supp:Ly on the transformer
side oE R3 through the llgh~ emittil~g diode LED-l. The
emitter of switch Q3 is connected to ground through terminal
32 and resistor R6. The base or gate of the switch Q3
is connected to the junction 28 on the high voltage output
of the transformer through junctions 34 and 36 and Zener
diode Z2. Zener diode Z2 has a breakdown voltage of approx-
imately 90 volts, and when the output voltage of the power
transformer exceeds this voltage, positive voltage ls
applied to the gate of Q3 to actuate the gate and ground out
the control wi~ding of the ~ransformer through the light
emitting diode LED-l. LED-l indicates that the necessary
voltage has been reached in the equipment to satisfactorily
operate all of the blasting circui~ry that is connected to . ;
the high voltage bus 30. Resistor R4 and condenser C3
communicates junctions 34 and 36 to ground to eliminate any :
high frequency that might otherwise be applied to the gate of
transistor Q3~ A condenser C2 is placed between the junction
28 and ground to filter out ripple from the high voltage
power supply. Diode D4 is connected between junction 20 of ~ :
the primary power supply and junction 28 of the high voltage
power supply to give a nominal 15 volt boost to the bus 30,
and thereby improve the efficiency, and reduce the length
of time required to adequately charge the equipment connected
to the high voltage bus 30.
The blasting machine of the present invention:further
comprises and utilizes a timing circuit which generates pulses ~ .
of predetermined length which are separated by adjustable ~ :
periods of time to give a total cycle corresponding to the
desired spacing between individual and sequential blasts or


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detonatlons. Tt is ~ furth~r Eeature of the presen~ inventlon
to provide a "lockout" circuit fvr thc pulse generator whLch
will prevent the c~ntrol pulses from being transmitted out
of the gener~tor to the various blast initiating circuits.
This "lockout" circuit operates in con~unction with the voltage
regulator circuit above described, and "locks out" the pulse
generator until such time as the voltage on the bus 30 has
reached the proper voltage for adequately operating the blast
circuitry attached to and receiving its energy from the bus
30. The "lockout" circuitry comprises a switch Q4, which is
shown as a silicon control rectifier, having its anode connected `
to the 15 volt power supply at junction 18 through resistor
R9. The cathode of the switch Q4 is connected to ground, and
the gate of Q4 is connected to the junction 32 that i9
supplied with the emitter current of Q3 and which in turn is
connected to ground through resistor R6. When no current
is flowing through the switch Q3, the gate of Q4 will be grounded
and the switch Q4 will be nonconducting, so that the nominal
15 volts will exist at the anode of Q4. This nominal 15 volts
is transmitted through conductor 38 and diode D6 to the gate, ;-
or base, of "switch" Q7 of the pulse generating circui~ry
which will later be described. The switch Q7 shown is a PNP
transistor, and the 15 volts which exlst in conductor 38 ~ :
when switch Q4 is nonconducting is transmitted to the base of
Q7 to keep Q7 turned off. However, when Q4 is turned on by
reason of the voltage having reached the necessary 90 volts
to pass through Zener diode Z2, Q3 and Q4 are turned o~, and ~
the voltage at the anode of Q4 drops substantially to zero ; ;
due to electron flow through the silicon control rectifier
Q4. Thereafter positive voltage can no longer be supplied
through D6 to the gate of Q7 and this then allows the normal
functioning of the pulse generator to take over 7 and supply

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;37~L
its c:ontrol slgnal to tllc g~te oE ~7. Switcll Q7 can then
turn on, and opcrate in L~s norlnally inten~led manll~r as w-lll
later be described. The "lockout" signal provided by the
s~itch Q4, in con~unction with the dual function of the switch
Q7, which normally operates as a pulse generating amplifier,
performs a unique safety function, which prevents control
signals from being transmitted'to the later described ~
individual blast c~rcuits before sufficient voltage is supplied '
to the individual blasting circuits to assure their proper '~
functioning.
The pulse generator of the present invention is
also made to operate at a voltage which i5 less than that
which is normally supplied, in order that it will be assured ,
of perfect operation even though a deterioration of the
battery or circuit components has occurred., The pulse gen-
erator is made to operate at a nominal 9 volts which is
produced from the 15 volt power supply by bleed through
resistor R27 connected to junction 14, and conductor 40 that
is connected to Zener diode Z3 which is In turn connected to
ground. Zener diode Z3 has a threshold voltage of 9~1 volts,
so that any voltage above this value is bled to ground through
the resistor R27. An adjustable amount of this voltage is
obtained from the sliding contact 42 of a variable resistor
R22 which is connected in series wit~ resistor R23 which in
turn is grounded. The adjusted voltage from sliding contact ~ ,
42 passes through fixed resistor R10 to a 12 contact switch
44 having resistors Rll through R21 respectively connected
between respective contacts of the switch 44. A condenser C5
is connected between the sliding contact 42 and ground to take
out ripple. The sliding contact 46 of the switch 44 is
connected by conductor 48 to junction 50 which in turn is
connected both to the control element of a switch Q6 and a



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storag~ conclcn~ser C61 the other side of which i5 grounded.
The val~le of R10 i9 selected so as ~o give a ]0 millisecond
delay ln chclrging C6, a~d each of the resistors R7 through
R21 have values to give an additional 10 milliseconds
delay for each of the respective resistors, so that when
the sliding contact 46 and all of the resistors including
R 21 are used, a 120 millisecond delay is obtained.
Resistors R10 through R21 can also be changed to give other
values of delay, if so dcsired.
Switch Q6 shown in the drawing is a unijunction
transistor, and the gate thereof is the emitter. The
breakdown, or the threshold voltage of the unijunction
transistor is such that when the voltage on the condenser
C6 exceeds this voltage, conduction occurs through the
base of the unijunction transistor. Base 1 of Q6 is
connect~d to ground through resistor R299 and the base 2
of ~6 is connected to junction 52 which is connected to
the 9 volt power supply 40 through resistor R24. Conduction
of-Q6 produces a negative pulse at junction 52 which is
transmitted through condenser C7 to the gate of switch Q7
previously referred to. In the present instance switch Q7
is a PNP transistor, so that the negative pulse from Q6
will turn Q7 on to amplify the signal if D6 anode has been `
groundedJ as previously referred to, by reason of Q4 having
been made conductive. Q4 is made conductive, as previously
explained, when the voltage in the high voltage bus 30
is above approximately 90 volts. The side of condenser C7
opposite to that which receives the negative pulse from
Q6 is connected to the 9 volt conductor 40 through a
resistor R25. The emitter of Q7 is also connected to the
positive 9 volt conductor 40 through a resistor R26, and

the collector of Q7 is connected to ground through resistor

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~63701
R30, junctio11 54 ~n~ resLstor R31. Refii~stors R25 a~ R26
are so selected ~Is to provide a negative polarity on the
base or gatc o~ Q7 by reason of a pulse originating from
Q6. Q7 amplifies this pulse, and ~his pulse is in turn
conducted from Junction 54 to the gate or base of another
switch Q8, ~hich in the present inventlon is an NPN
transistor. The emitter of Q8 is connected through Zener
diode Z4 to ground, and the collector of Q8 is connected
to the primary power supply ~unction 14 through resistor -
R28. Zener diode Z4 is selected to maintain a back -~voltage of approximately 3.9 volts on the emitter of Q8 when
it is conducting, so that a generally square wave shaped
pulse is produced on the signal output conductor 56 from
the pulse generator. Resistor R32 is connected between
the output conductor 56 and ground to assure an immediate -
drop in voltage after the pulse is transmitted. Signal
output conductor 56 contains a second element S2B of the ~*-
"Fire" switch S2 which is normally open to prevent the
signal from being transmitted to the charge detonating
circuits, later to be described, until such time as the
"Fire" switch is depressed.
Socket Jl is used to provide a quick coupling for
a battery charger, and for a circuit tester, which will not
herein be described. Signal output conductor 56 is
connected to terminal 6 of socket Jl. Terminal 5 of `;socket Jl is connected to a second element SlB of the
- ganged-"Charge" switch, and pins 4 and 5 of plug Pl are
interconnected to ground terminal 5 to terminal 4 through
ground line lO. -
It is a feature of the present invention that the
blasting machine utilizes a control pulse generated by
the charging and discharging of a single circuit, as opposed
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637()1

to a pluraLity of difrer~n~ circults, so that tllc spaclng
b~twe~n con~rol pulses will be ~ubstantially identical
and thus very ~cc-lrate. This control pulse is communlcated
by signal output conductor 56 to a plurality (usually 10
or more) of substantially identical cap lgniting conductors,
one of which 62 is shown in Figure 2 of the drawings.
Figure 2 of the drawings shows the first section (Section 1)
of ten sec~ions, and section 1 is the first to receive
the pulses from the pulse genera~or.
Once the "Charge" switch Sl has been depressed, and
the light LED-l is lighted to indicate high voltage~ the
"Fire" switch S2 is depressed. A train of pulses at
a predetermined spacing is delivered to the signal output
conductor 56, which train of pulses is delivered to an
electronic control swi~ch 0101, which in the present '~
instance is ~he gate of a silicon control rectifier, through
resistor R35 and diode D7. A stabilizing resistor R36 ;
is connected between the signal output conductor 56 and ~-
ground to assure that the voltage will drop appreciably
in the conductor 56 after each pulse is transmitted. The
anode of Q101 is connected to the high voltage bus 30,
through diode D101, and the cathode of Q101 is connected
to ground through junction 60 and a one ohm resistor R102.
One side of a power storage or detonating condenser C101
having more than sufficient capacity to ignite a blasting ;~
cap is connected to the discharge of diode D101, while the
- other side of the condenser C101 is connected to ground
through resistor R103 and the normally closed switch S2C
of the "Fire" switch S2. A full 90 vol~s, therefore, is
slowly accumulated on the condensor C101, and the corres-
ponding condensers of the other nine blasting sections,



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provL(Ie(l ~lla~ ~he "Charge" swLtch Sl has been depres~sed.
One of the ss~ety features of the pre~ent Invention is
that the power storage condensers, and all o~ the other
power condensers are prevented from accumulating a charge
prior to the tlme that the "Charge" switch Sl is depressed.
This safety feature is accomplished by means of the
normally closed switch element Sls which is connected
to negative bus 58 and which in turn is communicated
through a load resistor R33 to the individual blasting
circuits. A diode Dl02 communlcates negative bus 58
to the positive ~erminal of ClOl to in effect short
out the condenser ClOl through the load resistor R33
until such time as the "Charge" switch is depressed.
The resistor Rl03 on the negative side of the condenser
ClOl is in tu~n connected by conductor 62 to the terminal
A of the cable connector socket J2, and to which terminal ,-
the line leading to the first of the series of caps
that are to be detonated, is connected.
It will now be seen that the switch element S2C
provides the highly desirable safety feature of shorting ;
out the cap detonating line until such time as the "Fire"
switch is depressed. A resistor RlO4 is in parallel
with the "Fire" switch element S2C to slowly dissipate
- the charge on the condenser ClOl if for some reason an
open circuit or very high resistance exists in the cap
detonating circuit at the time that the "Fire" switch
S2C is opened. The first pulse delivered to QlOl therefore
allows electrons from the condenser ClOl to pass through
the cap to ground and back through QlOl to the anode of
condenser ClOl to dissipate the energy in the condenser
and ignite the cap. This flow of current produces a
positive voltage at the junction 60, which in turn is

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pass~d tllrougll resistor R:L05 to th~ gate o~ a sLgnal
transfer switcll Q102, wllich in ~he present instance is
also a silicon control rectifier.
The catllode of Q102 is connected to ground and the
anode of Q102 is connected through resistor R106 and
resistor R107 to a 15 volt bus that is connected to the
15 volt power junction 18 through switch QS, which is ~-
a PNP transistor. The base of Q5 is connected through
resistor R8 and conductor 64 to terminal L of socket J2,
and a plug, not shown, is used to jumper terminals L
and N to ground when a sequential operation of the
blasting circuits is desired. Conductor 64, therefore,
will normally bias Q5 "on", so that the 15 volts at
terminal 18 is normally communicated to the anode of
switch Q102. A resistor R7 is connected between the base
of Q5 and the power terminal 18 to limit the bias that
is delivered to the base of Q5 by the grounding of
conductor 64. The positive 15 volt power supply from ~-
resisto~ R107 is also comm~nicated through resistor R106,
resistor R108 and resistor R109 to the gate of a shorting
switch Q103, which is shown as an NPN transistor. The
emitter of the transistor is communicated to ground, while
the collector of the ~ransistor Q103 is connected through
a diode D103 to the gate of a switch or silicon control
rectifier Q201 of the second section, not shown, but
which corresponds to Q101. The signals from the pulse
generator are also transmitted from the signal output
conductor 56 to the gate of the second stage switch Q201
through resistor Rlll, which corresponds in value to R35,
-30 and the diode D103, which is similar to the diode D7.
A resistor RllO communicates the base of Q103 to ground
so that a positive bias with respect to its emitter is
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10~i370~
normally mnintaine~l upon the sw:itch ~103 to short Ollt
the s:ignal th~t is transmltted to the gate of the second
section of cap igniting circuits until such time as
C101 has properly fired.
As previously indicated, the firing of C101 .
produces a pulse on the gate of Q102 (if the current
discharge by C101 has been greater than a predetermined
value) which switches Q102 on. A light emitting diode ~'
LED-101 is placed in parallel with resistor R106, ~o
that when Q102 is turned on, the cathode of the light
emitting diode LED 101 is grounded, and sufficient
current flows through LED-101 to produee a light whieh
indicates that C101 has been diseharged. A eondenser
C102 is connected between the gate of Q102 and ground
to produce a delay in the actuati.on of Q102 for such
period of time as assures that an adequate eha.rge has
been transmitted from C101 to the eap eireuit to ignite
the eap. In addition to lighting LED-101, the actuation ~ ~
of Q102 grounds out the gate of Q103 9 whieh is normally ~ -
"on", to turn Q103 off, so that the next pulse whieh
is experienced in the signal output eonduetor 56 will ;~
no longer be shorted out and will in faet trigger the :~
eontrol gate of switeh Q201 of the immediately following
seetion that is conneeted to signal output eonduetor 56. .:
A eondenser C103 communieates the junetion of resistors
R108 and R109 to ground to provide a minimum delay for ;-
the aetuation of Q103, whieh minimum delay is longer than .:
the pulse duration. This assures that the second seetion
does not beeome triggered by the same pulse whieh triggered
Q101. ;
With the exeeption of switch SlB, resistor R33,
resistor R35, and diode D7, the remaining circuitry
~, '
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~0~;370~ ~
sllown in Fi~lre 2 will be exactly duplic~ted for
each sec~ion that is connected to the signal OlltpUt
conductor 56 other ~han the last section. The l~st
section will be the same as the second section just
described, excepting that no shorting out switch
comparable to Q103 and accompanyLng circuitry corres
ponding to R108, R109, RllO, Rll:L, condenser C103 and
diode D103 is required.
As previously explained, the cap igniting conductor
1-0 62 for the first detonation section is connected to
terminal A of the socket J2 of a cable connector, and
terminals B through J of socket J2 are similarly connected
to their respective detonating sections 2 through 10.
The plug P2 of the cable connector has its terminals A'
through J' adapted to engage the respective terminals
A through J of the socket J2 9 ancl has its terminals L'
... ,, . ,, - ~ .
and M' jumpered. When plug P2 is utilized, therefore, the
base of Q5 is automatically grounded to turn Q5 "on", - ~ -
to thereby assure sequential operation of the blas~
sections 1 through 10.
It will now be seen that the individual sections -~
of the cap firing circuitry effectively "cascadel' the
control signal from the pulse generator from one section
to another without the signal passing through the preceding
section. In the present invention the control signal `
is transmitted si~ultaneously to all sections, but
"lockout" means or "shorting" means are provided which
disable the control signal on all downstream sections
until the section immediately upstream to the section

in question has successfully fired. It will further be
seen that a mechanical firing switch is provided of a

type which grounds out each individual cap firing
conductor until such time as the "Fire" switch is actuated.
~.
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bc/~ ~

~0637~
One o~ the eL~ments o~ the s~ln~e ~wit~ll dlsconrlects the
control si~nal o~ pul~e gencrator frotn the cal) ~iring
sections until the salDe "Fire" switch Is actuated. The
"Charge" switch also has an elemen~ which grollnds out
all of the firing condensers until such time as the
'lCh~rge" switch is actuated to charge the condensers
immediately before firing. It will further be seen that
the high voltage circuitry for the power transformer
will have many applica~ions other than in blasting machines,
as will the disabling circuit for disabling the pulse
generator prior to the time that a proper voltage has been
generated by the power transformer. The arrangement of
using sequential signals from the pulse generator to
sequentially turn on a plurality of sections of other
circuitry also will have many applications other than in
a blasting machine; and the individual sections and
"cascading" arrangements will likewise have many applications
other than in blasting machines.
While the invention has been described in consid~
erable detail, I do not wish to be limited to the particular
embodiments shown and described, bu~ it is my intention to
cover hereby all novel adaptations9 modifications, and
arrangements thereof which come within the practice of
those skilled in the art to which the invention relates.




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