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TME_WJ.R€L:ESS^J.. NSTJ^TUTE
OF AUSTRALIA"
TASM. AN IAN DIVISION
EOX85U, &. P. 0., HOBART
DECEI43ER'1963 K3KTHLY BULLEPIN PRICE 6d
FE2SIDEN2 TREASURER SECRETARY
Mr. T. Aller. Mr. C. Harrisson Mr* K. Spiegel
\rs~l^ VK7G1 VK7KS
•iiResis-tererl a-t &. P»0. , Ho'bar-;., for •transmission by post as a periodical.
G^£RAL_MEETING»
The nexfc monthly raee-fcing of -bhe Division m. ll be held in the Club Room,
14.7 Liverpool Stree-b, Hobarb, on. t'JEDNESDAY^ 4-bh December 1963 a-b 2000 hours.
The lecturer for the evening will be Mr. I'G. chael Coles and his subjec'fc
"12 vclt DO - 240. volt AC Transis-fcor Converber"
NORTH: S)ESTERNZO?TS-
The n8xt. ineetlng of -fchis Zone mil be held in Lakin's Hgll, Ulverstone,
'• on TUESDAY, 3rd Decseraber a-b 2000 hours,
KQP^HErcLZOJ%.
The^ meeting -b^s month will be held on FRIDAY, 6th December at 102 Char3.es
Stree-fcy Lsuncea-bon, a'b 2000 hourgf
:i:PleaEe note •fchat this is a week earlier than usual to enable arrangements
to be; made . for a 'proposed Gl-j.'is'baas so ciala
FEDER^_CpUNGIU,QR^
Gongra't'ula'bions to Ted Cruise VK7EJ on his re-election unopposed as
Pederal Councillor for the en. sui'-.-g 12 mo'i-bhsn
Ii^EER.AL_GO^TMTION,
Nou is the time to consider items for inclusion in the Agenda for the
next Convention, to be held this coming Ess'ber, -Send-bhera along •to the Federal
G&uncillor •'. c'.thou-fc de2.qyc
PRESID. ^lF^SJSPOE^^^HAJ^EST, ^ VK7^1L
G-jr second post-war Hamfes-t has passed-and for those who were unable to
atte'nd for rea sens besfc Idioz'm't-o themselves I am very pLeased to report that the
function "ua s ageiin, higKLy successful,
A-btendgnce total vras 47- mem'bei-'s made up of South 31> North 11 and North
Vest 5i Couiitof'cars on the Sunday -was 34«
The VHF Hun-b and a "Name -fche Voi"cs" contest -uas held together with an
impromptu general meeting., The contests irere both won ly Geoff D'Emden VK7ZAS«
A raffle was v.Ton by Mrs , Ben Kelly and a VPO presen'tod Ty lan Nichols VK7Z2 vas
von by R, J. Ge eve s ^
Prizes, for the Gon-flests uere presen-fced. 'by Philips Elec-fcrLcal Industries
P+,7., Ltd,, 73 Brisbane S-fc,, Hobarb, and our thanks are herety esAended to that
firm for -the dona-fcioris
Tha "Name the Voicoa" -was a tape made and arranged by Jack Batchler VK7JB,
• №f •bhgnl<:s go to •those who macLe •fche week end a success by attend.ing and
also to those Council members and friends who toiled so hard "to arrange the
details for •fche Hatafest a-nd- make it a conplete success* We now look foridard "bo
our 1964 Hanfeato
COUNCIL,MECTIK3,
The ne^A Gounci]. Meeting •will be held a-fc -the residence of our President,
on MONDAZ, l6t, h December at 1930 hourso
The^Wireless Institute of Australia. Tasmaniga Division.
December 1963 Monthly BulLotin. Page 2
I. T. U FUND, ,, -
This month donations from VK7SE, . VK7AI, VK7ZAL, -VK7DC, VK^BR and VK7JD
s re acknowledged with thanks,
Amount received to 18/11/63 ;
Northern' Zone '£3 . .• ., ,
North WGstem Zone 4-10-";
Rest . 35-U- 5d
Sotal £43- 4- 5d
Our request last month for an indica-fcion of how "much w may- expect to
receive a-b a later date has at least showi us that we cannot. count'on anything
from voluntary donations, as not even one member bothered to reply. It appears
that we now have no akterngtive . but . to make QI levy next year on all raGmbers
.
' •-•p*., of course, those who have already contributed.,
OUR II^TITUTE fcy. VIC.7ZZ
Our Ins-fcitute is what we make it, and there are those amongs-b us who do
more than -their share in making our Ins-ti-tu-be what it is, and our sincerest
t!l??^go. 't?. the1?1 f?r ^hQ^r e:x:Gel3-ent work, Just to mention a few examples
, •uithm. ut. wishing -bo hurt -fchose omit-bed. The Secretary and fhe'lino oF'his'
Prsdec®ssor5, the Pederal Councillor who gives up each Easter for our sakes,
•the Broadcas-b OffiGers, and Councillors spend mgiy hours a year over and abovB
attending^ meetings open -bo all in the pursuit of Institute business.
MLght I^^ggost -bha-b ea'ch of us giyo our Institute even four hours a year
-just one morning - then our Division would cer-fcainly progress much faster.
. Ser\ace: can-. be in many forma. Not all of us are suited to construct gear for
cha?:table b_ocues? not a11 of us can :I'^ 9 library, no-fc all of us c?m organise a
or similar function, no-b all of us like fox hunts or field day s, "but"
surely most of us could^help to make a cup of. tea grid wash up the cups"af-ber a
meeting and s-weep the club room, as an example of sor'vice.
ThirJc it over chaps and see in what wsy you can help our Ins-fci-bute,
COUNCIL NOTES by VK7EB
Yo^^ Council met at the Club Room on 18-bh November, all merabers being
present^, Businefig of general interest was as follows ; Merabershi « "Reportel
ty ^ our Legal_ Officer ti-ia-fc the legal limit of memborghj. p inthe~Division"has''been
ralse?^to 300<'. New. Members. Tw qpplications for membership uGre passed for
submltting to Gntea1 Meeting, one of which was froa №. L. Gun-fcher, exW6.
Welcome -bo "Down Under" Lee'and we sincorQly hopQ you take out"'a'Licence'whilst
in Australia, ^ _rac s Allocation, It has besn dscided on an International basis
^
?oc*allo/Ga'be^l44. '~. 14-6 ml s .for wrld •wido ama-beur use, whilst in Re^.on 3 144 to
-mc/s'^pub\lclt. The
VK4. Division is nego-fcia-fcing uith'-the--appT
*
Opriate"
^?^i^e?..^.-u;?*A' ^ith,a '". ew -bp displaying the Oscar satellite in the "Capi-taL
of Australia. One^ does not hs^ve to have much iraagina-fcion-to for3e& the~
?ll?li,ci?^po't'en'fclal Passib:l-e" Ad^ce to Associates. Tha-b piece of surplus"or
•home "built- gear in your shgck- TRANSi^ITTING EQUIIMG№ I raean---I know'it^Looks
.
nice, Probably_mx-ks FB too, but it isn't wor-bh being confiscated-pius~a
'"'fine\,. DONtT. _BE. TEIlpTED', 7' G3T YOUR LICENCE BEFORE YOU U SB. IT. "Ity" suggestion"'^
make the transmitter section inopergtivG, then you wn't; 'be foolish.'
. GLlB_ROOM_nJND-
Our thanks_.to Ian_Nicb3ls VK7ZZ for his dona-bion of a VFO unit which TO s
raffled. at_the_Hamfeffct. By some_s-broko of good fortmie it-uas'wn~Ty'Ian"'himself,
immedlai fcQ donated
ly ba'ck. 'bo ."bhe_Iristitu-fce and TOS than raffled a^in'.. "As iTresuS
of -this the funds benefited ty £$- 9s/-. Balance of tMs-fund'T0 ~now £426-U^Td.
BULLETIN
test ^shem?o^d^^r^e^to,^^^^^^
theirfanili9s
73
Chas. Harris son VK7GH
Bulletin Conunit'fces
The Wireless Ins'bi'fcu-be of Australia, Tasmanian Division,
December 1963 Monthly BulletLn, Page 3
TECHNICAL.
0 WATT "DO IT YOURSELF" EC DC CONVERTER ty T. Al.Len VK7AL
Following details of a possible plentiful supply of Ferrite cores froia
defunct EHT TV transformers and the sale of some 2N301 -bransis-bors by the
Disposals Committee (all sold - CH) i-b -was decided -that something should be done
regarding put-bing both of these together -bo provide a cheap, efficient power
supply for po r'table/mobile use. Transistorissd supplies are not new, but -bo be
able to "'do it yourself" gives a great deal of satisfaction - if you are -that vay
inclined of course I
The story is as follows ? Carefully strip down the transformer so as
not to finish with too raany pieces of ferrite -• it is a very bri-fc-fcle substance
and needs a little care in handling. One or two heavy thumps generally results
in more pieces "than you can reasonabLe use»
Cut two 2" end cheeks in thin bakelite and cement firmly to former kindly
provided by the -bransfonaer maker. This gives you maximum winding space a s you
can work right over to thecheeks and not have your i-Tinding slip off the edge,
The primary wi.nding is not Ufilar wound and in order to make it a li-ttle easier
it TO s decided to use 2 strands of 20 B& S side by side for each half of -the
winding, instead of •brying to bifilgr wind two stffands of about 14 B & S« Result
is a few more ends bu'b a lot less effort. The feedback winding is just an
ordinaiy smngle layer centre -bappsd, The secondary wLnding •will consis'fc of a
number of layers each paper insixLated and. depending on wliat voltage you want -bo
obtain these Igyers will. be a lot or a few, Rectifier system can be half viave,
full wave, bridge, voltags doubler or what have you.
A few resistors and condensers' are added for de spiking, bias and to allow
for ch aracteristics spread in -the transistors.
Now to business i Take about 30 feot 20 B & S and fold in half. Leave
a'bout 6" protuding from one end cheek and holding both wires flat -wind on. 30 •fcurns,
cu-fc wires and feed through holj s in other cheek. Now we have two starfcs and two
finishes to half the primary labelled 31, Fl, S2, F2. Noxfc rGpeat above id.-bh
remaining wire giving two more starts and finishes labelled S3, F3, S4? F4» This
is important, as w© must connect the S and F correctly to get oiir uLnding correctly
phased (See diagram) The remaining windings are qixL-fce straight forvard. For the
feedback winding take 30 feet 25 B& S and vind on 15 turns, make centre tap. and
iri-ndon further 15 turns. Secondary ; 29 to 34B&S ratio approximately 2^ turns
per vol-fc. 400 -turns gives about 18Q vol-ts EMS,
The circyi-b shovm works •well. and if you don't hear 1500 cycles when you
apply 12 volts reverse either the secondaiy ends or the feedback ends (NCff BOTH)
It should then sing along gaily,
Results from the first "mock up" were ;
Secondary ; 378 turns 31 B & S (all I had;;) 420 is suggested,
Voltage s Outpu-b 275 @ 80 ma, 305 @ 20 ms,
Input 12 volts @ 2. 4 Amps (Max)
Efficiency; 76^
Tests; 6 volt input 135 volt 35 ma» 8 voU iraput 135 vol.-t 50 mg
10 " " 230 " 65 " 12 " " 275 " SO
You vri. il nots -the sane transformer and circuit iri.il operate -fchrough a largo
variation of input voltage. For rectifier I used a voltage doubler circiu-fc,
Remember : (i) Insulate transistor from heat sink with thin nica sheet,
(ii) I-b is not recomnended -that the uni-fc be operated on "no load" for too long,
. 27/200 Primary
•••^——
^ISB'} /^(T
31 r^m. lF s S3 /?w F^.
.
^. See-. |^2 Ff-j 64 F3
^ VolAage &
Rectifier
System to
^ 6. 8" '
•~'.. ^<.^/v_.
150 suit, GoU CT Coll
•I—s^t*—-^ Transistors : 2N301, 0026,
. 27/200 -^. Heat Sink, About 15 sq ins blackened
for each transistor,
^A/i<M->.2>
5 B.
i
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