AEC COLLECTION. fcc UNCLASSIFIED UNCLASSIFIED. REPORT NUMBER,4 4C zo -. )'5 I/ 5 NOTICE

Transcription

1 UNCLASSFED REPORT NUMBER,4 4C zo -. )'5 / 5 LEGAL NOTCE Ths report was prepared as an account of Government sponsored work. Nether the Unted States, nor the Commsson, nor any person actng on behalf of the Commsson: A. Makes any warranty or representaton, expressed or mpled, wth respect to the accuracy, completeness, or usefulness of the nformaton contaned n ths report, or that the use of any nformaton, apparatus, method, or process dsclosed n ths report may not nfrnge prvately owned rghts; or B. Assumes any labltes wth respect to the use of, or for damages resultng from the use of any nformaton, apparatus, method, or process dsclosed n ths report. As used n the above, "person actng on behalf of the Commsson" ncludes any employee or contractor of the Commsson, or employee of such contractor, to the extent that such employee or contractor of the Commsson, or employee of such contractor prepares, dssemnates, or provdes access to, any nformaton pursuant to hs employment or contract wth the Commsson, or hs employment wth such contractor. LECH~NELOGY D SERAL UNTED STATES ATOMC ENERGY COMMSSON Techncal nformaton Servce Extenson, Oak Rdge, Tennessee fcc AEC COLLECTON UNCLASSFED

2 Sc 004-A(3-55) ---.a NE; THS MEMORANDUM S NOT TO BE RE - PRODUCED WTHOUT THE EXPRESS WRTTEN PERMSSON OF SANDA COR - PORA TON. w MMM TRANSSTORS Counters Neth Pollard - 43 ABSTRACT Two transstor plug-n decade counters are descrbed, one of whch operates over the SCS-7 temperature range. A transstor dgtal scanner wth storage and parallel readout s descrbed. t utlzes one of the plug-n decades. A smple desgn procedure for flp-flops s presented. Work performed under AEC Contract AT-(29-)-789. Case No metadc00780 May 29, 95' 00 -

3 TABLE OF CONTENTS Page A 00-KC TRANSSTOR PLUG-N DECADE COUNTER A.4-MC TRANSSTOR PLUG-N DECADE COUNTER A TRANSSTOR DGTAL SCANNER DESGN PHLOSOPHY FOR TRANSSTOR COUNTERS. Typcal Desgn for a Flp-Flop Frequency Response Consderatons..... Trggerng Fgure LST OF LLUSTRATONS. External and nternal vews of a 00-kc transstor plug-n decade counter Schematc dagram of a 00-kc transstor plug-n decade counter Counter sequence External and nternal vews of a.4-mc transstor plug-n decade counter 5. Schematc dagram of a.4-mc transstor plug-n decade counter. 6. Top, front, and bottom vews of a transstor dgtal scanner Schematc dagram of a transstor dgtal scanner 8. Transstor dgtal scanner block dagram 9. Flp-flop crcut confguraton Transstor statc curves Flp-flop crcut Flp-flop crcut for two condtons of collector resstance Composte characterstcs for two temperatures Common-emtter output characterstc Pulse-routng dagrams

4 TRANSSTORS Counters A 00-KC TRANSSTOR PLUG-N DECADE COUNTER Photographs of the 00-kc decade are shown n Fg.. The package dmensons are roughly -/2 x 2 x 5 nches. The schematc dagram s shown n Fg. 2. The crcut conssts of four stages of bstable multvbrators (flp-flops) and two feedback crcuts whch artfcally add sx counts, thus.changng the scale-of-6 to scale-of-0. The nput and couplng crcuts each consst of two AC gates connected n parallel to provde proper pulse routng. The countng sequence s as follows: Postve nput pulses havng a mnmum sze of volt versus mcrosecond are counted n bnary fashon through the 7th pulse. The 8th pulse sets a "" n the 4th bnary whch then sets the 2nd and 3rd bnary to "", thereby addng a 2 and a 4 so that 8 counts look lke 4. The 9th count looks lke 5, and the 0th count resets all bnares to "0", causng a postve step to appear at the output. *The countng se juence s shown n Fg. 3. To reset, the bases on the rght-hand transstor of each flp-flop are momentarly grounded, turnng on those transstors. Ths condton s defned as "0" condton. Of course, t s possble to use a negatve supply also. n ths case, those ponts marked "+" are returned to ground and those marked "ground" to B-. Reset would then be accomplshed by returnng the bases to B- rather than ground durng reset. The decade wll operate over a supply voltage range of 2 to 35 volts and a temperature range of -90 to +700F. A.4-MC TRANSSTOR PLUG-N DECADE COUNTER Fgure 4 shows external and nternal vews and Fg. 5, a schematc dagram of a decade counter whch wll respond to pulses havng a repetton rate up to.4 mc. The Sylvana 2N94A has an alpha cutoff frequency of 6 mc and a common emtter gan of approxmately 0. Therefore ts common emtter cutoff s about 600 kc. The flp-flop operaton s pushed to twce ths amount by employng emtter followers n the cross-couplng crcuts from collector to opposte base. A better mpedance match s obtaned wth a resultant unloadng of the collectors and much faster swtchng tmes. The maxmum resoluton frequency of the counter s then determned as the pont beyond whch the loop gan s less than. 4

5 - Ll r~. kt ~4 - -~ - -, -a '~r S f., (yy -- D, 4 u N f 6 z f { 2 s 00 j j j q 0 U) 'V. ~ 7- V K. -~. r_ ew q '~. e'--~ ~ t J-.. - la external lb nternal Fg. -- External.and nternal vews of a 00-kc transstor plug-n decade counter Q" 5 5

6 7." D ' // dt R '* 'CwL~croRq.,_ 74-0 s- $ 24 // C6 C// C,, 430 Cd L cs 7 R- 75 C9 75 /OK C4 430 R/O /09 j/29 C7 430 /30 A3- R R/S,P0 O - K C/ C'4 430a epe Rao F- ra C, Jo x /3 /"K / 7 P/2 /$ <. /5M /22/< /Sk R32a /5* 93' /S/< 7y o.' R4 20K 53,4 rp? V 4 4 K/3.OK 9/2 cge. - Q - oo R ')u3-, K~~ _ Q /! Note: All transstors are type 2N23 Fg Schematc dagram of a 00-kc transstor plug-n decade counter

7 OF N t COUNT VOLTS(F B+L) OUT t 5VOLTS) CONDTON EACH' B N A R Y O- "2" 00 0 'S'S 0 8 "4" ly' Fg Countng sequence - evg 7

8 ..4 - '.~ 4 t ~, j *~ c <2. ~.- 'H { :.4. _ t~ c~ce'jc~ t..w.~y... - qj $ 2. - fll C -. - y ~ yr; d /7 4 4: r f F 4a external 4b nternal Fg External and nternal vews of a.4-me transstor plug-n decade counter C j 8

9 _ l~ = D K K 2K -07 Q8 2K 2 K K - 2K K 2K KH D3 D4 5.K K 6K 5. K D 7 D 8 5. K ~~05 '0 06 6K 6K 5. K D D K 6 K 5.5K D 5 D 5.5K K 6K K K a 20K 20K D lk L _lk DS 00-20K 20K t -= D : K 20K 0 K 03 D4 20K 20K 00::. 00-0O 4 - _- A' 8 ' 3 >;-+0 9> - 0 PNS 56B 2 NPUT PN 4 RESET PN. 8 OUTPUT 0 THRU 06 ARE SYLVANA 2N94A D THRU 058 ARE TRANSTRON T9 K OHMS ALL CAPACTORS ALUES N MCRO-MCROFARADS MC-DECADE SCALER Co Fg Schematc dagram of a.3-mc transstor plug-n decade counter

10 Negatve pulses are requred to trgger the decade. are +0 volts 2 and -0 volts 2. The power supply requrements The same feedback scheme s used as descrbed for the 00-kc counter. A TRANSSTOR DGTAL SCANNER Fgure 6 shows top, front, and bottom vews and Fg. 7, a schematc dagram of a counter and storage devce. The devce wll count for a perod of tme governed by the "start" and "stop" commands and store a fve-decade number (through 99, 999). t wll count pulses greater than 0. 2 volt n ampltude whch have a repetton rate below 3. 5 kc. (The repetton rate s lmted by steppng swtches whch consttute the last three decades.) The frst two decades are the 00-kc, plug-n counters descrbed prevously. There s no vsual readout from these decades, but there s a relay samplng matrx connected to each. The last three decades are steppng swtches whch provde ther own storage and also drve ndtron numercal ndcators whch provde vsual readout of the three most sgnfcant fgures. The specfc applcaton for whch the scanner was developed s to count output pulses from a Geger-Muller (g-m) tube for -mnute perods and to provde contact closures so that the number stored can be punched automatcally on BM cards. The scanner was connected n parallel wth a commercal dgtal scanner for 0, 000 operatons and showed exact agreement. A block dagram of the transstor scanner s shown n Fg. 8. The pulse standardzer shapes pulses generated by the g-m tube. Both the pulse wdth and pulse ampltude are determned by the pulse standardzer for all pulses generated by the g-m tube that have an ampltude greater than a preset threshold. The ampltude of the pulses generated by the g-m tube depends on two thngs:. The tme between mpngng beta partcles and 2. The sze of the capactance from the anode of the g-m tube to ground. The tme between mpngng beta partcles determnes the ampltude of the g-m tube output pulses when the tube does not have a long enough tme to recover between mpngng beta partcles. Therefore, an ampltude threshold s set so that there wll be no dfference between counts from one dgtzer to the other. 0

11 ' s cee - top vew 3 $-.u front vew -t * bottom vew Fg Vews of a transstor dgtal scanner

12 + / - /2- + V SV _. -45V A+5V OvC05 C8 Rh R 2N43A ol 2 82K A 6 PEjET BUS R V 5V OK -O R SV 33OLUF MEG J4C6-lRe 03BAKC 66 C00 6KV 0 K 02 2N C - 04 UUF NPUT FROM -02., U3 GEGER R223 C2N23R N MEG K6 2 24K H- VOLTAGE 2w R3 C K 2 4K C V +K 4V 0 K K UHF "+5V +5V 30K (BACK) +5V C3,3DECK C V 4 +r5 4 C0 C R24 C N C4 R CR R22 30K 30 5K 029 M6 5 C R25 C R27 R9 F4SK 00 0K 4 + SOV K26 +5K A3 4SV N58 T5 4 22K_ 2N43A 6 C4_ -' T 24 C DECK C - R R ok 5 PN4 E WPER6j -2C e 22.44K V u DECK E 56 3S MS NUMER CAL 2 '- ( FRONT NDCATOR PANEL) Hl C B R6 R R7 KS 3 6K 44W 00 RESET 2 w RESET C9 000 T K2 l R65 C39 _ DECK ~~ C K R 2 R58 74 K 8R60 K9 R62 K7 R K2SPRN36 DEC K E R 87 TRRU R MEG EACH /2 w 42R4 R32 M -30K R5 3 K q}7 30K 3040 K250K 00 Ol N43A 2N43 2N43A 2N43A 2N43A 2N43A 30 3 R K C K 39 C9 5K 00 R33 9K C8 R38 39K +v 5K ;00 5K ~ V +5V V+5V. R4 47 TOGGLE CR 02 0.Ge NSS PDGE 2N43A 2N RLK L Ds RED SYO PRMARY AC RECPT. 5K 39K (BACK) C20 C2 + R V 50V MEG 7- FTO FTD 2 CR N58 BRDGE ~ VAC 4 30 PRMARY -45V -45V SUPPLY C SOW 4+ 25W -3 COLUMN EMTTER 3 43A R49 KS K3 30K 30K 30K 30K 30K A4343A348 7 READ 9 C27 R63 C2 R7 394 R5 24 R K C R 6 39K R? 5K 39K 3.8K 2 SK39KS0 3.5KV2W 6 + V.+5v +SV +5v 64 R V30K 30Kr0023' 0 K3 A K2 A S4 }A COMMON FROM 5 DECADES no's COLUMN-E M FR TE R " K9 494 COLUMN EMTTERS R69 R69 C30 S.K 39K o.krttkh, 022 Z CS3[9 4 MOM COUNT N93 NC R78 K6 R80 R83 NO 36K N0 2wE7 50 C35 82 C37 :O25 7K MOM- MCRO NC - c E R N W C MCRO K4 PN4 DECK C- STAR L < TT DECK E TO DECK _,000'S A- 9 COLUMN EMMTTER ON JONES STRP RELAY NOTES DECKS A 6 H ON RELAYS 4K 8 K2 ARE DENTCAL TO DECKS - Tm A 8 H ON K 3_ EXCEPT AS NOTED BELOW ALL 4ESSTORS /2W UNLESS SPECFED 2 DECK HON 6 GOES TO M3 3 DECK H 0N 62 GOES TO M4 Z KK4K3,K4.4,K6,K7, K8,K9,K0,K9 ARE CLARE, 300 OHM, 4 WPER ON DECK A. K) GOES TO 00'5 4-S3PR0,K K2 K3 ARE A STEPPNG, K4,K 5,K6,K7,K8 COLUMN EMTTER ARE SLARE RP-3630, OCTAL PLUG-N (FRONT PANEL) 5 WPER ON DECK A, K2 GOES TO 000' 3 M, nq ARE TRANSSTARZED PLUG-N DECADE COUNTERS COLUMN EMTTER 4 M3%8, t MS NATONAL UNON NUMERCAL NDCATORS, 'NS. RON -0' DECK H l DECK H H NDTRON SUPPLY 476 CR CR 0.2 MEG Sv - 5V f + C32 65MA 65MA 20 UP - S0V C33 20UF 5OV V DC - NDTRON SUPPLY S 'S 0' s O'S h,00d0,000's JONES STRP ON BACK OF CHASSS L-LT-O- -- -R-* -- _ SCHEMATC, - -- TRANSSTORZED -. '.".- DGTAL SCANNER -,-w--k40)608 Fg Schematc dagram of a transstor dgtal scanner OJT 2

13 - N NPUT PULSE STANDARDZER OO'S 000'S 0 K'S BS DECADE OSDECAD DECADE DECADE DECAD E (PLUG- N) (PLUG- N) a a A STORAGE STORAGE STORAGE START COUNT STOP COUNT.SO'S VSUAL SAMPLNG SAMPLNG MATRX MATRX READOUT RESET T READOUr y wool, PARALLEL READOUT TO BM PUNCH -45V SUPPLY FOR RELAYS 5 60 "\L + 5V SUPPLY FOR TRANSSTORS SUPPLY FOR NDTRONS 220V Fg Transstor dgtal scanner block dagram The coaxal cable that connects the g-m tube output to the pulse standardzer must have a partcular length snce coaxal cables have capacty and wll attenuate the g-m output pulse. n order to standardze the count between unts, one defned coaxal-cable length must be chosen. The negatve-gong output pulse from the g-m tube s appled to the base of Q through the dfferentatng network C and R. Q s an emtter-follower whose nput mpedance s approxmately 2. 5 megohms. The basng network, R and R 2, holds Q near cutoff. The negatve-gong pulse drves the base- negatve whch causes the emtter to follow the - base wthn 0.2 volt of the base drvng pulse. The negatve-gong pulse at the top of R 2 s appled to the base of Q 2 through the couplng networkc 2 and R 3. Q 3 s a pulse amplfer Corrected 7/30/57 3 r' 0?

14 /6 whose gan s set approxmately by the rato of the collector-to-emtter crcut resstors. The- nverted and amplfed pulse s coupled from the collector of Q2 to the base of Q 3 through the dfferentatng network, C3 and R6' 3 s a hgh-gan amplfer and also sets the threshold level by means of the emtter-base basng arrangement. When a count s desred, relay contacts connect the base of Q2 to ground through R6. The emtter bas s set by R 8 and R so that Q3 s n the off condton. R 8 and R9 are adjusted so that a 250-mllvolt pulse at the nput of Q from the g-m tube wll cause Q3 to conduct. The 250-mllvolt threshold senstvty s chosen so that vacuum tube and transstor dgtzers may be compared. When the postve pulse appled to the base of Q3 exceeds the bas voltage appled to the emtter, Q 3 conducts. The pulse at the collector of Q3 s amplfed and nverted. Ths negatve-gong pulse s appled to the base of Q 4, turnng Q 4 on. The collector of Q4 rses to +.4 volts. The rght-hand sde of capactor C6 whch was ntally at +.6 volts rses wth the collector of Q4 to 23 volts. Ths acton turns off the base-to-emtter dode of Q 5 by.4 volts. Capactor C 6 charges through R, Q 4, and R 5 untl the base of Q5 reaches +.6 volts. Q5 starts to turn on. The collector of Q5 rses toward +. 6 volts turnng the base of Q4 off. The collector of Q4 returns to ground potental. Capactor 6 dscharges through a low-mpedance path, consstng of R 0, base-emtter dode of Q 5, and R 5, to ts ntal condton. The postve-gong output pulse s taken from the collector of Q and routed to the nput of the frst decade counter. Ths output pulse s of fxed sze and shape, ndependent of nput, fora wde varaton n nput pulse shape. Detals of the relay samplng matrx are apparent from the schematc dagram, Fg. 8. The output from each bnary of the decade s necessary to drve the matrx. An emtter follower, Q 6, for example, s used to solate each matrx relay from the decade. The man.vrtue of the transstor scanner over the vacuum tube verson s the reducton of power requred and a resultant reducton n heat dsspaton. The vacuum tube scanner has seral readout and requres external crcutry to swtch ts storage matrx from one decade to the next, greatly ncreasng readout tme. The external crcutry also requres an addtonal power.supply. DESGN PHLOSOPHY FOR TRANSSTOR COUNTERS Typcal Desgn for a Flp- Flop The general crcut s shown n Fg. 9. The object here s to have the "on" transstor held n conducton by bas voltages provded by the "off" transstor. Lkewse, the "off" sde s held off by bases provded from the "on" sde. f the "off" sde s turned on, the opposte condton wll preval. 497ye,? 4

15 RC RN -VOLTS RN RC Rb.Rb Re Ce- Fg Flp-flop crcut confguraton Consder a flp-flop bult around PNP transstors havng a collector voltage ratng of -45 volts, a common emtter gan of 50 at 5 ma, and a leakage current, COB' of 0 mcroamperes. To hold a transstor n the nonconductng state, the base-emtter dode must be backbased;. e., base-postve wth respect to emtter for a PNP. f only one supply voltage s to be used, t s then necessary to have the emtter potental below the most postve pont n the crcut. Ths s done by nsertng a resstor n seres wth the emtters. t s then possble to drve the bases postve wth respect to ther emtters. Snce one or the other of the transstors s always conductng, a DC potental wll exst across the resstor, R, n common wth both emtters and can be held reasonably constant by connectng a bypass capactor, C, n parallel wth t. A crude crteron for C s that the R C product be long compared to a trgger-pulse length. e e A desgn center of -volt back bas nsures adequate margn for wde varaton n transstors. Therefore, we shall desgn conservatvely for a 2-volt drop across the emtter resstor at 5 ma. (One uses 5 ma because ths s well wthn the ratng of the transstor n queston. ) 2 R =-=400 ohms e 5 Snce the collector voltage swng s approxmately equal to the supply voltage less the emtter voltage, and a large swng s desrable, the emtter voltage should be kept reasonably low. 5

16 f we assume that the "on" transstor s saturated (collector postve wth respect to base), then the emtter-to-collector voltage s less than /2 volt. The saturaton voltage can be read drectly from the transstor statc curves (see Fg. 0). SLOPE = RSAT C -- 5MA VSAT. VC Fg Transstor statc curves Therefore, usng a negatve supply, the collector of the "on" transstor s at VRe + VSAT below ground, or about volts. For a 5-volt supply, the drop across the "on" collector resstor s = 2. 5 volts. For c = 5 mls, b = = 0. ml B50 nsert a large safety factor here to nsure suffcent base drve for saturaton, say, 0.5 ml. Then, neglectng the forward drop across the emtter-base juncton, Vb for the "on" transstor equals Ve = -2 volts. Choose R large wth respect to the emtter-base resstance, say, 0 k. Then R =Ok = 0. 2 ml andlr =b + R = 0. 7 ml. b n b Now determne R. c Consderng the "on" transstor - VSUPPLYVc _ 5-2.5=2.4 K c= c RbOFF Now determne RN. c"off" = SUPPLY -Rc RN = x 0.70 = 3.3 volts R = c"off" ~-Vb"ON" n RN 0.7 6

17 t The fnal crcut then appears as n Fg.. 2.4K 2.4K -3V.7MA -5V 0.M OFF-VON 5K 5K t-2.5v '5MA 0 K 0. MA OK -2V 0.4 K -2V Fg. -- Flp-flop crcut Check the cross-couplng crcut for the off base; RN 25K = 0. ml (b"off"=0). VbOFF.= 0. ml x 0 K = - volt. Snce the off emtter s at -2 volts, Vbe = volt, and the transstor s turned soldly off. Ths flp-flop s bstable. untl the other sde s turned on. That s, the sde whch s turned on wll contnue to conduct The safety factor bult nto the base drvng current should receve some comment here. One reason for a large safety factor s that the common-emtter current gan, B, s greatly reduced at saturaton. t s not unusual for a transstor to have B reduced by a factor of 5 for saturaton versus nonsaturaton for the same collector current. The actual B can be exactly determned expermentally for a partcular transstor. t s only necessary to obtan a set of statc output characterstcs and read off the rato c to b' f the flp-flop s to operate over some temperature range, then the most straghtforward desgn approach s the followng. Consder the two condtons llustrated n Fg. 2: condton for a collector resstance R and condton 2 for a collector resstance RL. The 2 two sets of common-emtter output characterstcs are to the same scale and for the same transstor at the two extremes of the operatng temperature range. away from the voltage axs as temperature ncreases. Notce how the curves move The mplcaton s that the transstor gan ncreases as the temperature ncreases. Generally ths s true. Also, the leakage current ncreases wth temperatures (doubles every 0 0 C, approxmately), whch helps to bas the transstor on. As a result of these effects, the same base drve, b2, for example, yelds consderably more collector current at hgh temperature than at low temperature. 7

18 4G lb3 'b5 A 0,0...,4--- CO ' b2 MONOGOP - z W b3 - z w cr 0 LU -J 0 0 >V >V >0 B~B2 b2- Na * 0L 0A 0 O C 0 w -J -J 0 0 B L B2 t6 L. 0 >0 *0 b COLLECTOR TEMP. VOLTAGE LOW Z 0 0V COLLECTOR VOLTAGE TEMP HGH Fg Flp-flop crcut for two condtons of collector resstance o

19 f the "on" and "off" base currents are b 3 and b, respectvely, the flp-flop wll not have two stable states for RL at hgh temperature, Al and Bl. Note that b, the base current for the "off" condton, s suffcent to saturate the transstor so the "off" condton,. pont B, s the same as the "on" condton, pont A. However, f the load s decreased to some value, RL2, two stable states, A 2 and B 2, 2 wll exst for b 3 and b, respectvely. A smple summary of the above: choose the "on" collector current larger than the "off" collector leakage current at the upper temperature lmt. The rato, of course, wll determne the output voltage swng, VC -VC ON COFF t s recommended that the output characterstcs be obtaned at the temperature lmts as the frst step n the desgn procedure. f the two sets of curves are supermposed on the same axes, Fg. 3, then the allowable range for the value of load,. e., collector, resstance wll be apparent. H ON LLOW ON H OFF C LOW OFF Fg Composte characterstcs for two temperatures From Fg. 3, RL s the lmt for the maxmum value of RL because at hgh temperatures, the "off" ntercept s the same as the "on" ntercept, pont A. The mnmum value of RL s lmted by the low temperature "on" condton, pont B. An allowable range for RL s between R and RL The requred output voltage swng wll then determne whether or not Ltet a s s o nqe to l m e h p lc to e u r m n s the transstor n queston wll meet the applcaton requrements. 9

20 Frequency Response Consderatons f the flp-flop s to be used at hgh frequency the frst consderaton s, of course, a good hgh-frequency transstor. The 3-db frequency n a common emtter confguraton s f /B. An SB-00 transstor havng an fa of 30 megacycles and a B of 20 could not be expected to operate above. 5 megacycles n a standard flp-flop confguraton. are: Certan crcut modfcatons wll result n mproved hgh-frequency operaton.. Connectng capactors n parallel wth each cross-couplng resstor, RN. These capactors allow large drvng currents to flow durng the ntal stages of swtchng, whch shortens the response tme. 2. Reducng the tolerances for "on" and "off" condtons. For example, set the "off" base at a few tenths of a volt rather than at volt. 3. Couple from collector to opposte base through emtter followers. Ths provdes a better mpedance match and greatly decreases swtchng tme. 4. Lmt the collector swng wth clppng and clampng dodes. The clampng dodes lmt the lower swng of VC so that saturaton does not occur and t, the hole-storage tme, equals zero. The clppng dodes permt the use of a hgher supply voltage than the transstor ratng and thus shorten swtchng tme. The crcut of Fg. 4 ncludes all of these refnements. These Trggerng f the bnary s to be used to dvde by two from a sngle source, t s nec essary to provde a routng scheme for the trgger pulses so that successve pulses wll appear on alternate bases. The trgger s usually appled to the base for that s the most senstve pont. Two AC gates connected together provde a smple pulse-routng scheme. Such a scheme s shown n Fg. 5. The dode bas.resstors, R, cause the dodes to alternately block, then pass the trgger pulses, dependng on the collector voltage state. For PNP's, a postve pulse appled to the base of the "on" transstor wll turn t off. Lkewse, a-negatve pulse appled to the base of the "off" transstor wll tend to turn t on. The reverse s true for NPN's. 4)

21 2.2 - w 4 C CLP V CLAMP s 'C RF RF RN CN CN RN VCLAMP VC VCLP COMMON- EMTTER OUTPUT CHARACTERSTC Fg. 4a Rb Rb Re A REFNED FLP- FLOP Fg. 4b Fg. 4 *4 4 o 40 w l -~ J - %- / A.. ~ POS. PULSE N" -yr NEG. PULSE N Fg Pulse-routng dagrams Corrected 7/30/

22 f both postve and negatve pulses are avalable frcmz the source, then the decson as to whch to use wll be based on whether one wants senstvty or speed. For maxmum trgger senstvty turn the "on" transstor off. Ths requres that the least trgger pulse ampltude for the "on" bas be only the forward voltage drop across the emtter-base dode, nomnally 0. to 0.2 volt. For maxmum swtchng speed, the "off" transstor should be turned on. Ths drves the transstor nto an actve condton,. e., a gan greater than. The other transstor s already actve so that- both transstors assst n swtchng. NETH POLLARD - 43 Case No