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m WJi^L^S JJ'JSTITU-I-f?
Of Ay§T;iALlA Ul 11111 LI! 1. 1 ll_i
TASMAN IAN DIVISION
BOX 851J, G. P. 0., HOBART.
JULY 1966 MONTHLY BULLETIN PRICE 5c.
EBESIDEHT; Mr. T. Alien TREASURER! Mr. C. Connor SECRETARY; Mr. C. Russel-Green
'VK7AL •VK7CT VK7CR
Registered a-t G. P. 0., Hobart, for -bransmission by post as a periodical.
EDITORIAL
On si-fc-ting' down -bo prepare -this month's 'bulletin, I find myself in -the ssme
Tsoe.t as th se who -tac'kled this ts.sh before me—— nothing -bo v/ri-be abou^. I-fc K-trikes
me as ludicrous, that in a, s-ba-te -the size of Tasmania, -there should be such aomplete
apa-thy &nd lack of co-operation in -bhe compiling of a news shee-b, -fchat is after all
for -the benefit and/or amusemen-b of all of us. The idea of the Bulle-bin is purely and
simply -to allow all in VE7 -bo knov< what is going on, what meetings and lectures e-tCo
are afoo-t, yet it is in these -things tha-t the apa-bhy is most apparent. And -the most
ludicrous part of i-fc 's that our hobby is radio, communica-bion our business, ye-fc I
have only once been con-tacted with any news whatsoever from -the North or Nor-bh-West
Zones,
If, in one state alone, -fche. zones anno-fc 'be induced, goaded or bribed in-bo pull-
ing -toge-fcher -to make one small effort a success, what hope has the Federal Executive
of getting Aus-fcralia as a whole to back -their efforts in the fight for retention of
our Am teur Bandso Anne VK7LY»
MEETINGS FOR JULY. '
JULY 5th.,.. Nor-th We s-t Zone mee-ting, Lakins Hall, Ulvers-tone, 2000 hrs.
6th. o. Headquarters General meeting, 147 Liverpool St., Hobar-b, 2000 hrs,
8-th... Northern Zone, Adult Educa-bion Rooms, 51 York S-fc., Launces-fcon.
18-fch... Council Meeting.
20th... V. H. F. Group Mee-fcing, Club Rooms, Hobart. 2000 hrs.
LECTURES„
Headquar-ters general meeting. .. . A leo-ture will t)e given:by Ted Beard, the first
of -fcwo, on Civil Defence.
THE MONTHLY BULLETIN OF THE TIRELESS INSTITUTE OF AUSTRALIA
JULY 1966 TASMA1TI№ DIVISION PAGE 2
SUBSCRIPTIONS.
Owing -to the soft hear-tedness of your Treasurer the axe, illustrated in la.s-b
mon-fch's 'bulletin, has been suspended un-fcil -the next council mee-bing. Accounts will
be sent to the 41 members outstanding, -fc'his being -the lastcorrespondece in connect-
ion with this •ma'tter.
41 members ou-ts-fc.s^iding-is approx.' 2.2%' of "'the '-b'o'-fcal membership, a pre-tty high
percentage in anyones language, and a disgrace to VK7.
REMEMBER— if you haven't paid YOURS, your fellow members are buying this
bullffitin; and A. R. for you. • ••
NOTICES
As .-this bulletin is being, printed so close -fco the oouncil mee-bing, -fcher'e has
been no -bime to Drenare -the promised lis-b of Library Books. However, this lis-b will
appear in next month's bulletin.'
MOW Tapes are now availa'ble from this division. If you wish. -fco -bake advan-fcage/of
this offer, send in a -tape to -the Secre-bary-w-ith de-fcails of your t ape'. recorder (make ,
speed, etc. ) and -the required MCVf speeds, please enclose return postage. . Do no--fc
forget •to ;'olearl!y state your name .and address.
FOR SALE.
By Jim Oliver, VK7JO, 73 Normans-fcone Rd., Launceston.
Item 1. 50 wa-tt CTiV trp^nsmit.-ber, Geloso VFO -bo 6146 final, with power sup.,
in case l8"x 9"x II"? needs only tuning- condenser to Tse on air. $38
2. Modulator for above, wi-fch power supply, on chasis ll"x II", $30
3. Small receiver on chassis ll"x 6t-",; covers 80 ajid 40 Me-tres.
6AN7? 2 x 6BA6 high selectivi-ty I. F., 6BL8 product detector,
6AV6, 6AQ.5 ^o 3" speaker. Provision for "S" meter and band
spreading on 80 and 40 using Jabel double reduction dial.
Less pov/er supplyo Will sell for less -than cost of parts. $36
We have been advised that ar-bery forceps can be o'bt. ained for 50C each. These
are high quality, locking 'typ®, ideal for transistor work or fine v/iring. Several
sizes are available. Contact the Edi'fcor, 223 Ba-fchurs-b St« , Hobar-fc.
DX
For the benefit of DX enthusias-bs, Poly VK7CK, has given us the following
information (per radio )»
10 IK. This band. has been spasmodically open -to the States.
15MX. Regular openings, mostly to the States and. Canada, and occasionally to
Sou-th America have been occurring for four, weeks or more 'between 0900
and 1500 EAST every day. Signals have been quite often up to S9 both ways
20MX. Poly has been working West and North Africa. in the la-te af.ternoons (1700
to l800 hrs) regularly. ZB2AK, Gibralter, has been qui-be consis-ben-fcly
strong. S-fca-bions heard and/or worked are as follows. ZDSCD, Ascension Is»
ZD7RH, St. Helena, CR6DX, Angola, 9L1HX, Sierra Leone, TU2BD, French
Guinea, ZD9VH, FB8YY.
Nearly every day ZS1, 5&6 in South Africa are heard. All -bhese have mainly
been shor-b path but occasionally long path, so it pays to check both v^s,
THE MONTHLY BULLETIN OF THE WIRELESS INSTITUTE OF AUSTR^LLIA.
JULY 1966 . . TASMMIM DIVlSI PAGE 3.
PROJECT AUSTRALIS.
Since publishing details last month, we have been in regular radio con-bact
with -the Mel'bourne University, and -the following information has been passed QUo
Several changes have l3een made, mainly due to the faclr that a battery of -the
required capacity was unavailable, and therefore power is at a premium.
Until -the Taa-b-tery is exhausted, af-ter 2 -to 3 months, there will be a continuous
transmission on 144. 050. This will carry telemetry information of which there will
be seven separate readings. The 50W) -bransmitter will emi-b -bhis information with
each read-ou-t -baking 80 seconds, made up of seven 10 second audio -tones and 10 sees.
of GW which will be "VK" transmi-fc-bed with 1 second gaps,
The seven telemtry channels are Ba-fctery Voltage, Bat-fcery Drain, Two Horizon
Sensers, Magnetic A't-bi-tud. e Sense Coil, Battery Temperature and Inside Skin Temp.
A ro-fca-fcing and til-bable an-fcenna is desira'ble for -bracking and -fceleme-try decoding
charts and orlsit predic-fcions will be made available.
There will be a beacon on 29, 450 mcs and to conserve -the Tsa-bteries, this will
be swi-fcched on by s^a-bions in W, ZL, and VK for aboui; 5 of tho 15 daily orbits. I-b
•will l3e comfflanded by a single channel receiver in -the satelli'fce, the command sequence
and frequency being classified information. This beacon, while on, will -transmit a
continuous carrier faa? 70 seconds and -the "VE" ga-ted in from the 144mcs transmitter
for 10 seconds. This beacon has a great deal of impor-bsjice, and due to high power
i-fcs operation 7i)ill have -to be closely con-fcrolled so -that as much informa-fcion can be
gained as possible "before -bhe Tsa-b-teries give out. If opera-fcions are successful -the
command information will probably be released a few weeks af-ber launch, so -tha-t
ama-beurs will be able to -try -bheir hand a-fc swi-tching the 'bea. con on and off.
If -time and man ower permit, -there may be ano-bhcr Taalloon flight early in July
to test -the command system. The fligh-fc model will be comple-bed by Augus-fc, and
forwarded -to the Salisbury Weapons Research Es-fcablishmen-t in Sou-bK. Australia for
final testing, from where, it will go -to -the USA for launch some time 'between
December 1966 and January 1967°
WIRELESS INSTITUTE OF AUSTRAEIA TASM.WI^ DIVISION
JULY 1966 VHF SUPPLEMENT» : By VK7ZAV
The fellows in -the Ho'bar-b area are really in -brou'ble no'w.-The two big noises on
the -Eastern Shore have buil-b -themselves VFOs. Congra-bs Barry and Dave. Both sigs
sound pre-b-by stable and you will now be able -to pu-t -bhsm to good use, as -there should
be a li-ttle DX around, about now. I heard somewhere on -the grape-vine tha-t -the VK4s
have l3een working JAo Usually about a fortnigh-t either side of -the shor-fces-t day we
get a li-fc-fcle DX in VEC7, sometimes at good s-breng-fch. Mother very big noise on the
6 MX bpjid now is ZPT, who has burnt ou-b receiver front ends over a 3 mile radius by
jus-b increasing his HT a li-b-b. le, and. adding a crystal mic. -bo -bhe rig. A really nice
sig. now Phil. We have -two new licencees in our midst now, one with and one wi-thou-fc
a call sign. Harvey, VK7ZHF is one, and has been on -bhe air since atiout one minute
after receiving his call. Congrats Harvey. ZHF is active on the ne-b freq.. mo'bile, &
arround. 145 mcs a-b home. Believe he will soon have 6 MX gear a-fc home alsoo The other
gen-tleman is David Johnson, v/ho; as mentioned earlier, has no call sign as yet. Hope
it won't be too long Dave, and in the meantime, guess you will l3e building up some
gear. Would like -to know wha* has become of Richard, 7ZRR. I believe you were on
a-fc one stage Eich. so how abou-fc firing up again. If you are having trouble working
out of your location, le-b the broadcast officer, or one of the boys know, and we
shall look for you af-fcer the tiraodcas-fc one Sunday. Once you have made a few con-tac-fcs
and the fellas know you're about, many more will follow.
Mike, VK7ZMC, has not been over-ac-fcive lately, as he is studying for-:'-exams, but
s,s a break from s-fcudy, he has majiaged -to rebuild a receiver he recen-tly aoq.uired.
At least -three and maybe a few more I have no-t hesird of, will be si-t-bing for the
nex-b CW exam, but we feel sure they will not desert the VHF bands.
At our last meeting we visited--the meteorology section of the DCA at Llanherno
Aerodrome, and followed , a wea-ther balloon, from take-off -bill burs-ting poin-b. For
many it was -the first sight of radar and proved -bo be very interesting. We now have
a greater insight in-to the peculiar noises we hear on 144 periodically, the harmonic
of the 72 mcs Walloon Sond. transmit-ber, from which temperature sn& humidi-ty data is
derived. A few facts gleaned during the evening may be of interest -bo those who
could, no-t at-fcend.
The 'balloon oonsis-fcs of a hydrogen filled envel-ope', roughly -bhe shape of an
inverted pear, made from a plastic type material. The 'balloon would be about 8 to 10
feet high and 6 feet in diarae-fcer a-fc take-off. Belovi? •this is strung a small parachu-te
and below -this again, s. radar reflec-tor, a -bin foil covered cardboard device, followd
by the Sond itself, a -brp. nsistorised -bransmitt. er in a c&rd'board box 6"x 6"x 8",
Tone pulses are -bransmi-bted which are recorded on a pen-recorder, to give, af-ter
suitable conversion tables are applied, -temp. -to within 1 degree accuEacy. The Radar
gives height, direc-bion and dis-bance, from which can be derived the speed of drift
and. therefore wind velocity. The particular launch we wi-btnessed flew for about one
hour and burst at a height of approx 60, 000 feet, landing in the s.ea off Marion Bay.
Each Taalloon costs about $30 'but few are recovered as -the prevailing winds blow thorn
in an eas-fcerly direction out to sea. The day -time flights use a larger 'balloon, and
reach about 100, 000 feet. in heigh-b.
73s till next month,
Mike, VK7ZAV.
,
-rC. Bg . MONTHLY BULLBt'IN''OF THE' ttlKEtj ESS-INSTIT. U. rFE OF AUSTRALIA
JULY 1966 "•'I1ASMAiaAIit,.. DIVISION- ^ ":;:. :•• PAGE
TECHNICAL
KIRCHOFI** THEVENlN, :. AN^:NORT^[ ,—by,. R. L. &un-ther (VK7RG)-;,'.
In ord'erfo have the,. ma-t.erial available-in'.'re'ferenee ..form, I shall here summarise the
Network Laws proposed, by. the.se . three wort'hy •geh-tlemen'. '.
Kirchoff'.s Laws
l) If a bunch. bf wires meet a-t;' one -po.int, the. ', sum of currents- flowing to -that point
equals -the sum of currents flowing-, away .. from it.. If ^ the currents flowing to . the poin-t
are considered .. posi-tiye, -and't-ho. se floining . away _ are considered negative,. •then in Fig. r
^--s. i-fcis eviden-t -tha-t II +12-13. -1. 4 -15 =0.
As i.t stands, this can .be useful in unravel-' •
^~
x, -^
^
^ ling various problems such as the distribution
of curren-fcs'in a cube, each of vihose legs-eon-
sists of 'a resis-tan. ce, as shown in -the Ij ecture
Fiff :of. a few mon'tj hs'ago. Bu'fc it is also basfcally
necessary for-fche working of Kirchoff'sSecDndLavi, the mos-b familiar one, -thus:
2) The sum of all' poten-fcials in a closed'. sys-bem. is zero, including vol-bage sources. The1
most useful, w^y'tovee -this idea is -fco as ign arbitrary current loops to a ne-tviork, and -fcheh
add -them up. in consis^en-t fashion. Consider, the exam.ple'.shown in Fig. 2. This could be
solved by simple voltage • divider rel^-tiion-
K::-,' ships,.. bu-t . will serve as a useful.; illustra-
+ tion fo.r the, method which can be 'applied to.
...'•^A- ^1. .
considerably "more ·complica-bed. sy stems, . '.g..
is the source of potential, with in-temal
R5- '+ resis-tance . Rl, and" we can assume ar'bitraiy ... :
.
'-f-~
R.
current la'ops, la,, Ib, and 1c, iNhich for.
simplicity (heh!') we can a e here to. be
^«=1
electron floyi.. Then the vol-bage <irop . across
.
each res.istQr is . of negative sign where, .the
Qj- ^ •eleo-trons enter, and posi-bive sign where they
,.^
?ie.'2
leave., ..Now imagine -that we know all-re sis-
tance.. yalues, and want -to know -the actual ...
curren-b flowing -through R3. As you can see, each loop has been assumed -to go an-fci- ,.
clockwise (i-fc is necessary only. -bo. be. consis-ben-b). If the arrow enters the. resistor at
the nega-fcive^end, -bhe voltage, is .. taken as nega-tive, and .. cbnver.sely... Then', '-as-'E. -=. '. IR, ;-^j,/.^_',1
and the sum of all'voltages in any one.. l.oop is-zero, •'••• . " ' -, Li
+E • -laRS • +IbR5 . -laRl = P ' On_ .
Ia(-R5-Rl '. +Ib(R5) ... +Ic(0') :; ..= -E
-IbR5 +IaR5' ->. IbR4 +I:c. R4 -I^RZ •= 0 Ia(R5) '. '. . ' ' +rb(-R5-R4--R2) ^+Ic(R4) . ,, = , Q..
-IcR4. +IbR4 -IcR3 =0 .... " "•" •'• •la 0,. . ... "+IT3 R4 • -::- ^-. +Ic-R4-R3= 0
We can solve the se --t'hree •'simultaneous' eg.uations'ih threei unknpvins,,. by. -the usual- aige-.' •
braic me-fchods. of subs-fci-bu-bion: or cancelling, bu-fc it is-'consi'dera'bly. easier fo'. use -the'- •'. '::
method of de-berminants, For t^is pur^.ose. i-fc is'necessary, ••to: se-fc..up a 'm.a-trix, ' and -tha-t
is simply a fancy"name for-'pattern. 1 The,. preliminary work for -Ijhis has, however, already.
been whe ft-the e:quati'ofts'were. rearranged,., as above right, .so :-tha-t. ^,all coefficien-ts of the
individual currents fell'ln columns., ./.••Now. -. f or. -fche ne3rt s-tep, since i-t is teaious always
-bo write 'R' in'-frolit df every value indica-b ing' a resis-bance, 'we oan simply -take -the
number associated'"wi-fch it.. ^ Thus, . instead-of 'R3'' vie ca.it gimp.ly write '3',. but bearing
firmly in mind-tha-t; this 'S'. is no-b a, nuntoer,' but an •alge'braic quan-ti-ty; if'.it'is less.... -., ,
confusing, you Sould'use 'A', 'B'., 'C', e-fcc, ''butI:-thinL k-fchata4ds,]US-b;one'more complex-.:
it;y. ' W@ wan-t't'o ••solve , f or 1c (going -bhrough'RS)., and'in ;this iiistance. it is:Ic=^P/Q, -. 'whe3re
-5-1
"^, ^s
-•5-1'i
"^ -E; . No-fce that '•'-5-1' is no-t a ^ process
p =• 's' -5-4-2 Q o'f 'subtraction or addition, but of"
.
.
•o :.o mul-biplic'a-fcion, a'nd is .equivalent •
' "to ''' (-R5) (-Rl)' . No-tice. -that P ' ' '':"
-5-1_ . 5 -^-
5 ^>» -5-4-~2
0, ^^':5-1^-5
4
'•0
-5-4-2 • "^
5
consists of three columns, •which are
repea-fced-again-to the righ-t, simi-
0. 4 -4-3 0 4 -4-3
larly for\Q.. In F.y. t.he, firs-t-tao
columns'are simply, the values'of'-the Te.sist&nce s mul-fciplyixig each cu^r.ent-;iand-tbe -third
column is-the one at the:: right hand side •, of ,-the eciua.!, sign.' This'is...a general, t'hisg;
The column. -£o -the righ-fc' of-the:. e.qua.l. sign..is. always su'bsti-tu-tied for Tfche co.&fficients of
-the. unknown, currenf" in t-hei':eqya-t;ion--ma-fcrix.. (-t;heil'onel T3etween: hon. zo.n-bal lines, above).
Otherwise . -the' coefficieats of. -the . currents in -the •eq. uation-matrix are reproduced-as-is. :-
in the: .de-termj. n:ant-ma:tri'x. ':(the. 'pne , 'b.etween -vertical-lines ;):»•''NO, ^!...in. & -the determlnan-fc
, : is,,j.den-b.ical ''t'ofhe'equat.ion^.. where all ."coefficients-to:-the-lef-t handside of the equal
sign are', reproduee d. exactly-in-the ^de-termiriant. ' The quantity'^,.'therefore, rem.ains the
same , ' wbateves valy es.... of- P. are obtainea wheh: solvirig:-fer the. vari. ous.,. currents.... . ' To .
solve the determinants (one a-b a time', of course), : y, ou . draw a ,, peincili line diagonally
:
through three values, and multiply them toge-fcher. . S'or.. exsmpl'e't. he first diagonal, is. t... ,
(-5-1) (-5-4-2) (0), which being transla-bed back to resis-fcances would l3e((PTO').)——^.,-
ff- -«>
... the MONTHLY--BULLEI-I.N. OF. -.THE WIEELESS. r.I.N.SD..ITUI.E OE AU.STRALIA ,
TA'SMANIAN DIVISION Pa e
Jul 1966
Kirchoffet al'(continued)-- . . ,..
(-R5)(-Rr)'(-R5)(-R4)(-R2)(o), remeffibe.ring that nega-tive multiplied •by nega-bive is posi-
-tive, 'and negative pultiplied'toy posi-tive is negative . And -fcha-t' zero .mul-fciplying-any-
thing is still zero'." ;In~-this instance, . becau'se of--the las-t-mentioned fao-b, the quan-fcity
is zero... ;. Now, -then, you go. on; ;t6'-the se'cond diagonal, ; add . i-t. to-the. first, 'add-the
third diagonal) subtr&c-b -the . f'durbh diagonal' vihioh now •gpes in .-fche Opp.o.s.ite direc-tion,
sub-trac-t-bhe". fifth.. diagohal', -and: subtract the • siscfch.. .. This can, bemade muchd. earer^by
doing~it:'^'=-I-5-^-4-2^o) +. (5^(OKO)'+ (-E)<5K4^.^- ^-5-l)(0)'(:4) -(s)(5)(0,)
- -(-E) (-5-4^2 )(G), :. and this" reduce? ^omh'^o ~P = ^-E)(R5)(R4). Similar, operation on"Q
yields .Q, =:.(R5Rl)(-R5R4R2)(R4R3)-(R5Rl)(R4)(R4) - (R5) (R5) (R4R3). The actual numerical
values f:or'^P.anA_S'are'found'by subs-fcitu-ting in the proper ohmic values for R, doing the
necessary ai^-fchme'fric, and •subs-ti-tiutihg'back into the original, 1c = P/Q. ' This take s...a
lo-fc' of vfords, bu-b it-takes less time -to' do, if you are careful. It is a very powerful,
-though tedious method for-solving a :w'ide varie-by of impossible problems I Conventionally i-t
is useful for solving -the bridge corifi'gura-fcion. The relationship for the balanced bridge
is classical, but when you want to know the vol-tage or •current dis-fcribution in an un-
balanced bridge (the cqhditibn where it is doing worlc), the more rigorous Kirchoff
method (or. Thevenin or Nor-ton) mu's-fc be u8ed.
If induc-fcances.'.or capaci-tances are involved, E^ =, L' (di/d-t) or EQ = (l/C)J. l(t)d-fc.
A good reference for. -refreshing yourself on calculus is " An Outline of -the.. Calculus, "
by C. O. Oakl'sy, in -the 'C'ollege. Outliine Series, ' or similar. Ifyou. ha.ven't had any
Calculus, not ;-fco Viiorry, jus-t plug in values and measure until -they work! I daresay -bhat
this applies' for all the. rest of. us -boo, Ui-fc i-b can be nice -to have -ttiese. more' elegant
methods available -if absolutely necessary'. My occasiQn for. refreshi.ng myself with -them
became unfortuna-tely necessary a few . months ago when I was volunteered into it... hi.
Two cau-bions in -the use of Kirchoff: l) A-b leas-fc one of -fche I'obu s'"must pass -thro-ugh
each Tol-bage . source. 2) To use -the me-bhod of determinan-bs easily, the. vol-bage sources
or zeros; ough-t;;-fco appear on the righ-t-hand side of the equal sign, as above. In general',
for a network , of n,. points, -there will be (n-l) simultaneous equations -bb" solve. This
method is applica'bte, of course, only when the values of resistance or reactance are not
dependent on the ins-baneous values of current or voltage in'the circuit. Thus, no
varis-fcors, -thermistors, semiconductors., or varicaps can be trea-bed by-fc he simple method.
Thev nin's The orem
Why this should merely be a 'theorem'., since it can be easier -than the 'law', I don'-fc too.
Rigorously i-fc is— The curren-t in any :-bermina-fcing impedance connec-te'd -to any ne-fcwork is
•the same . as... i.f-the impedance were connected -bo a generator whose voltage is -the open
circuit vol-tage of -the network, and whose in-ternal impedance is -the impedance looking.
baeK from the. terminating impedance, with all genera-bors replaced by impedances equal -bo
the internal impedance of -these . genera-bors ! Oh how those Engineers love the sound of
words. I-fc is appreciably simpler -fchan -that in prac'bice. Consider the Poin-bs, A, and B.
in ?ig.. 2.. I"b -burns out -that the whole circuit can Tse. simplified -to result in the
configura-fcioh of Fig. 3. The current through R3 can now be found by the simplest appli-
Fig. 1 -^AA^ _F-A ' cation of Ohm's Law, I == I/R. StEA-B is the
»A6 R: equivalent voltage of the new circuit, the
-Aft
^8 vpl-tage which will appear across points AB if
Bfi-'-is remcved, and RAB is -fche resistance^
across points ^ if/R5 is removed, and "fche -voltage source, E (the original one) is
shorted... Bu-t remember tha-b E is the ideal source, and has an internal resistance, Rl,
which must be •fca ken into ac.count if appreciable. Now this method fflill reduce -bhe"circui-b
to a set of vol-fcage tividers, in the case of I*'ig. 2, the voltages and resistance of which
can be solved in elemen-fcary fashion. Thus, Ig = EAB/(RAB + K3)* The method •will work as
well. for solving the currerrb in .any other resis-tance of Fig. 2, if •tha-fc resistance is
assumed -fco "be -fche_'termina-ting iiBpedance, ' and 'A. ' and 1B' chosen eiliher side of it. If
Theyenin's Theorem were applied to the symme-brical network of a bridge (remembering that
in-fcemal resistance, R^), -the bridge mill simplify. more easily if all vol-fcages and re-
sistances are. referred with respect to an arbitrary common line {e. g.-, one side of the
voltage source). ' . :' •
Nort.on^s Theorem
Much .like Thevenin, ' but using an equiyalen-t curr&n-t;., ins-fcead,. of vol-tage. Next -time.
FOR. SHAME 1, if. you have . no-fc subscribed to -fche Equipinen-t Exchange Bulle-tin. I-fc is a
magnificen-b publication, casually covering prac-bically every-bhing--technical, using a
simpleminded approach tha-t -thrills every.one. Send for a free . sample (or buy it at -OBM's)
from P. O. Box 177, Sandy Bay, Tasmania. You'll never, regre-t i-fc 1 .... VK?RG is the main
Edi-fcor, so. he jus-b may happen to have a few copies' on his person at -bhe next Meeting.
Response to'the offer of wholesale-prices for -bhe Techpress Publications was disappoin-fcingly
small, so they will'no-b be sent-for... )—RLG