BSTJ 10: 3. July 1931: Negative Impedances and the Twin 21-Type Repeater. (Crisson, George)

14.6 MB·English

‘Negative Impedances and the Twin 21-Type Repeater

BES nee gaia ee ene

AVES ent atid othe trina af aetna pte
VV ccsctasre © curse fo ip at the terminal snnested to the
positive pele uf she sour ar tat the other ternal. ‘This iw
tian ef ete Ty ie eansidered positive and the value of the resistance
Rin ahs piven hy Dhan as R/T where Bis the appice
Yeluige sna Tox the covcert in anaperes. Silly alent eurreve L
say be peed throngh the vealstance aid a een ial lence a kop
E— RI wil appear ares ie rerminlas Wil portiveresieancee fe
takes diverenee whe'her we "epply an em." oF "ssa cur
The rsince may bea very simple deve ucla ii wie which
slheorbs energy from the cenit at arate IP El — PR watts

TU possible, towever, tc construc scan lay of aya which
have the property nt keeping tlw ratin wf the vltage acess a pir
tevminalsto the cure at he ermal constant, ut with the relative
tedstance wuld gives Ta sich devioes the ceistae is acgative and
‘the apparatt conteibutes per tothe eirnit with whieh its cm
eted Pach such devine neces inaes x source cf energy sur
fa battery aud some seas url at seein tbe for cootallig he
Metvery of es energy tothe circuit. There ave two varieties of wach
Hevices, In one cae, the Zaremal arrangement of the scan ic
uch that, if» dente yolege fe applied © tie terials, a corrert
fleys in a diretion onporite t she applied eam tn Ue ther,
definite curvent is panied thragh Ue system, he dcop seca the
terminals wil be opposite ia dirt tn Uaat exused by a poscive
sistance. "Thiow ‘su arrangements ae eesanitily dierent ad
cannot be uel terchsrge fa given circuit, thn ther one can
tive any dedized value of negative resistance, ce wvomg arrange
ese is used invalil'y ur siaging wil occu, To how whether
fiven negative resistance will Werk sacinfarily in a given cree ite
Hot sufiien: to know ite value it lis. Something must be known
shouts intanal arrangement sad abont the impedance of the cteuit

in which ita to wark

Rusesunarren Nraunve Ressrasens

(One of the simplest wae to produce @ negative resiatanve i to inter-
rpnmmes: the ipa aud ouput fermiaals of a one-way ample. This
ves # ecenevative argent because part of the euiput exegy
Dt the amples in fed back nro Ce putczeuit. The eymeo uegtive
Frestance cbi‘ned depends upon the way which the imereanmtion
unde

Fig. 1 shows schemaceally ws ial aaeoway’ armplifer for this pos
poser It han a pref inp terval, 2, aad a pair uf ovis
fninels 3,4. The ipeeances between Uh ingut and ont terminals
fe pure ierstances #, and, respmdively. Some mechanistic
fate sywillcy fy he eet, i persild, whick pred
inthe enti circu which t propericas! to Fe pur enment. The
fuetug of fis sechariam i iopostance ro thie vessinn exoept
thas ie a ne-way device, The autual impede fis the cao of
the emf, gromrated in she outa: Gee: co the curren: in txe put
Greuil, This sao may bw sjusted by sultalie sneans euch
potentiome'er hue ie others cnastant and includes no phase shit
‘The incercl connescions are aseurse to be auch that when he input
terminal Lis poskive wo? thee in tke ouepot ret tends to make
fevminal 3 positive with respect to 4

Seates Neste Resistance
In Fig. 2 the input and sitpit eireits of the ideal amplifier are
‘commscte in seieg wih eal her 6 source of ean. B ani a re
stance Ry fn eh fashion thet the ean, ia the uit circuit of he
Amplifier tends :o inreige she cuiens. sume now tbat tye eam
{is applied and a eureut Zp ows in ive series sic,

BS GIR R~ Re=O. o
‘The drop exces the amplifier i:

= RAIN, ®
snd the net resistance oF the whole smite i

-PO ROR &

11 my aid in undersanding the behavior of Ue system 9 sesume,
frat Time is 22:0 50 tha: the clteull cnasale sim of the tice
vWsitive rsstances Me, and in aries nd then Consider wast
opens as Fis gradually incense, The eat. sppenring he
put eet of dhe acpliler aces to ceduee she drop # acruss che
terminate 1, and to ingesse the cusreut Jy The ems must be
revue ifthe currents eo be kept constant. The eerver of Hig. 3
ew he the sesstances ane curren: vay ax AP whomgee,
When = Rs} Ry the crap ¢ ard resistance ¢ bec zero,
he arnpier then cease co take power sot the evel. nl pies
is own laste. 11 his condition could be exasly obtained the tere
sivas 1,4 might be sharecieuited gad the en remove without
isang che cirent scien wedlel continue 0 tow hn the ani ee
, however, the em. were removed o¢ the eiveuit oped without
Sovtceuiting the terminals ol the ampies the cuscest fa te iat

fieeut, and, movarqueatly, che eam. 'n the eutput cieait cf the
fmpliee Would disappear a the system world heeomne inactive

1M, om, is Cather sacs so Var aponouches = R= Re
he cunient “erence inline, ne Ce ean F reid so aust

che current cta given value approacher zero. Cnelr thee conditions
the drop ¢ an the cexistanee 7 hncime negat've and the empltier
supslice uo: ony ‘tec “aans but alea sare of tae energy disipated
by the resistance 2 It doce 0 under the control of he cx key
however. and if this ems is removed tbe syateut Incomes active as
before. At tae Bimit when 2 = Re-bulh Pe amplifier supptes
al the loses in le system ey cre Z, once started, eaatnes
Indsiitly

This eal conciton ie not realized in practice, Either A is lightly
‘oo small a which cane tie curt decreases Wass I is restoved or it
is tou lige that any value F however small starts curren! whieh
therearer increases Eecane the ampliber supplies tore thar. enough
cregy surtain the enment, This inerense nontiaues util decked
By le inabilny ofthe ampli to dea wit larger currents. In lft
Af rele tthe point whene aga equa: to — Re after which che
frrens continues sta constant value

“The arranenwt sown in 13g. 2 cm therefore be made to provide
any negative reste beaneen 7 = aad? Ri without causing
instability or w teudeney to sng. Such a system ds sie sion the
lige sun of ell the resistances dn teres oe Ohe civast is patie
This beavine cs typical of large number of serangenencs that are
able to finsisk negative resistaneee, All te arrangements will be
Feferrsl nas series neg esstanrse to dstngi then rom another
‘ype whieh wil be dese=bed nin

Te sould Le noted that if the sgn uf b reversed, for example, by
inmerebanging the fw wires commested with the outpue terminals 3,
fovamaive tesistanor reals Ae AF iaerases, che viel fe de
freaies os the em E must be inesied to inintain the rurent
fut neater how lange side, thevlreting ofthe drop ead sign
ff the restance yo wl change though the lees arcs

‘Tux Usgrants Coxpinos

So far nothing as en etd av the acute ofthe eam Rn che
‘deal ete, when the sytem eee, se currane wave isa cy of che
Yoleuge wave a5 in any eiveie having a pure resistence, What hap-
diene wien theciceit i antable depends upon the nature othe ample
Fer or other device used to proluve tbe aegaive resistance snd not
fpen de ecul F. This may be of any Kind end of rsnate si, such
1 that resulting from teem agieaos in che cesses forsting
port uf the apparatus, Ifthe amplifier sable wo amply det ur
ets, the reeulting scurbance may Tea divectcurzent ied waly
1 the aiity of the spyecatus to eupply eneess to she sircsit. Where
tramfurmeie, condensers, ete, are iveclved the distebance sees
low to at altering euiien? which my contain many Iamonite
Girma be alts pce gine yave. Tees e*ecte ane called “singe
Jing.” The fal frequeney, amitude sad wave shape lepeul pon the
Irkeup of the apnicatas int way which ie beyond Une cope of this

Suust NeeaTnR Russstanes

[By connecting the: ermine of te kal one-way empl in parallel
te alown in Pig. 4, negetive sesstance Wl be obsined which
typical of the eel ee oF she! nee resistance,
Referring tn Fig. 4, the currestn ts inputciatof Ube mpi is

“

Fis Caner arating popes of os npc

‘he eset he aye cet

©
0 BELL SYSTEMS TECHNICAL sOW'RNAL,

and the curren’ fuss sain erie

RARo,

nbn BARE oT
foo wi
ti @
RRS RaW n
ani he apie voto 2
RRR,

a= nomen ft .

|W de emagemsae, the emul generated in the ouepue clseuit of
the amplifer opposes the cimrent Jy cue so Ube ean. £, and as 3
Inevees, the current fein the an cree deveined the vesetanee
ff tie smpierincreaces, Te eure of Fig. 5 show how the es.
incor and cusent vary se M changes, # beng eonstast. To lxep Jo
Constant fe woul nov be rennry to Increase F

‘When AF — & the current fs hevvmce 2225.

Whes 2° — Ry ty the current dy calls» am, the potential
ea Fy the eusent fy has reversed indirection, Ne veistance + = ©
fw Hie ample: just exoptien ste own Joces." If eke cient onside
the soupitir snow opened Ue condor o: the aepliiar isthe same
fo wna the shore cient wa applied to Pig. and ce cures ecu
ing in the smpiter wil eowinae, 40 is moved without opening
the dee will drow energy fom the arapier, taue reducing Tal
tousiig all coveents and wtages to disappesr. "The amplier is sel
lier the onatol of the ere

For the asaigerven of Fp 4 to ecome wnt ts necessary for
tne samplifer fo maintain or eease te voltage «alae the controling
fei disnemevee For the auplier tomaintain the wolnge eit
sevseay chat

_ Ra,
ey Rt
BYR
EniR®

o
fora whieh

Fiky ‘
+ BS, 0)

and foo ()

Hone it

the impsonce
the yen cane.

4 nopove resttoce greater Si mogndnde hee Ry Lt
because the ampilercniol maine o increase
the vwlige © after E is removed, even thong the current
esinet ane esau fe rmecving eneegy fom te api

TH if meinen seater than the upper zit given oy equstion (0)
thesysitn paonce out of conirl by the emt. Rand Becomes unctable
Grsines. By shur-cinitng the terminal 2, t would be possibie wo
rence 10 unl st ie reater than the value given by equation (10)
fpoice niki male ¢ anmericlly ssuller thar & On removing the
Thore cheuit, nowever, w disturbance wow begin aad grow unt
Checked ly he limitations of the amples so tha, inet, wold
be reduced onl agata made equal ly —

Ti is revered i ign for esinapie, by Inteschanging the wo wices
eonneecr tre cigut tenia 3 4, no nogetive resistance ren
[Se Af ancceases, the euvent fe ineesees. "The wesiarance decreases,
‘pprowcing new ae becom iceinitly great

From laa spent a aegative restr of muy died
vale may’ be fasetes in a Grail having any positive resistance 8,
provided that the inact! paistanne has the Chiraeteistics of the
ors tye wl the iaerted negative ceistarce is rmeresly smaller
than the panitive resstance or the elaractsstce of the shunt type
Tehen the negative restive fe numedcaly lager than te postive

Goon Tomas ur Newanive: Resterance

AIL owes devices for pring negetive resistance fal into ove
cor the ther of the tw canes deastbed above

Arringeneats are Krone wich eabibie one type ef negative re
sistance a one par of terminals and the other tye ata differen pair
Dur nos ht yes atthe sme ee of terminals 2 the same ie,

‘Ceres apinnatus involving giemnas encduetien of eectroi di
‘igegeevhiit negative tesisance elec, Fig. 6, for example, shows
tee fing between ton electsedes whit are conmertod 2s
{Mien reseiane ad inductance serving a5 ballast toa snusee of er
Dower, ‘The Tallat serves to stabilize the are nl il the current
Arne fom the seucee coraiant ad alco ce prevert the wavege af
Sltermeting eurene throws the sure fens the arc, The are hs
positive rvsinnce with respect to the da. circuit ent gonsumes
(Ee, power, us thie resistgnie varies with the current fn swe 2 «ay
that on increase of euivene fs sermmsiie! By a reduction of the po
tential drop ssi the are.

Tres allerating curent is superimposed upon the direct eurvent
‘ieough the vrs y gana ef the tie waned i enseuntins a aeyative
Fesitance. Ifa crv ooneaing of a eeietanze X, idorvanre Fan
sonlenser Cie bridged acros the areas lion ancl tl resistance is
made lage, nothing occurs, bu if che wsstanr rece 0 2 certain

cal valus & state of owilation ie establisd, This oilaion
Fuses an alternating armen inven through che resonate cecuit and
Uheare. TF the oscllaton is of audible freuen the are wt emit a

singing o: whistling sound. "This openly of Ue ate es found useful
Applieation as a gene:atey of higheCeqursey ovilatinas isthe Polke
fre mse in raocelegeaphy. ‘The negative revstance of the aze has
‘cis choracevstice ae sections wll ant ewcur if chee fs an exc
of postive cesisae ia the m'llating, ret

The dysatean,'on the other hand, has shunt characteristics a it ie
vastable when le excrrval pasate Se made ge,

Nuavrave Resisrances oF tio: Iowa 20 yew Ciecurr

Fig, shows the ideal onesray-amsoliger of Fiz, 1 connected with aw
ideal iybeid wal w fort 2luspe repester cirenit. The ie hybrid

cole esumed to have
Tigibie racing, enerent

ines of ero resistance, no leakage react:
6 between she windings, no core los end nex
“This 2.-¢ype Greuit fe comnested berven be ecual resetanoes, Re
Ro= HAR sd Re Be, sosning thatthe hybrid coil is designe for
feaual imeauses at the tee alts af ine terminals and the drop
eeivinaly an ems, & acl serioa with the reitame Re at the
Tet side of the repeat: and the mutual inipedance A of the amples

as)

foye a the lfc hand ternale 5, of che bei coil and in the input
Cont of the arptier, One-lf of the power estriag che repeuter
js uote ia the input resslince Ky of the amplifier and the other
hal i abserled ia the omepnt impedence R.. Tn acodance with a
‘roll own prapercy uf te hyd ei no eure wll How in the
Tinlichand resistance Ry. Abu gives inceant ths inpnt eure may
te auaursed co have the diretion indlivated by the chort straws J
By incvecsing 27 “he amie: ean be ride active, ecusizg an arphied

nt fat fow in series through the line witdiogs of tha hylrl ei
lind the connected resitances Ry By rowing the reversing switch to
te side [a ray mal to do fa the sare ecedion aa Iya tre tee
thinals 8, # a8 indicived hy the Toa arrows matked fy. For con
‘enieace, thie will he "wleril ta the "inert onaectien.” Changing
the veversing mecteh changes che divetien of fy with resect i Fy
fiving the "reverse continu.” Ae the bybeid eol i balers, the
utput power of the amplier does not react upon the Snput eeu
Putting for the emlifying rato of she 21-ype eves

ap

“The total euvert Donna the terminal 8, 8 is

<Abh

~A4)

tl he active resstanee of fie 2-tyre cee is

14x, co)

As the amplifietion is irwasee, the curent Zs inceeaces while + falls
te zero and beconms negative, thus exiting weron charactvstics.
TA is incsosed without init," apmragekes — Bi magni but