Common-Emitter Transistor Amplifier

SyncWare Co.

Products: Common-Emitter Transistor Amplifier

Date: 1983

Type: Cassette

Platform(s): TS 1000

This program designs and analyzes common-emitter transistor amplifier circuits. It stores up to three transistor specification sheets (not five as stated in the external description) covering parameters such as beta, H-parameters, thermal resistance, and frequency characteristics. The program iteratively solves the Q-point bias equations using a convergence loop that accounts for VBE variation with collector current via a logarithmic model, leakage current temperature dependence via an exponential thermal model, and junction temperature rise. It draws a detailed ASCII schematic of the amplifier circuit using block graphics characters, and performs small-signal analysis including voltage gain, current gain, input/output impedance, low-frequency 3 dB corners for three coupling/bypass capacitors, and high-frequency bandwidth using a Miller-effect capacitance model. The BASIC code makes use of POKEs to the display file for direct screen manipulation, a machine-code return via RAND USR, and a subroutine dispatch technique using computed line numbers.

Program Analysis

Program Structure

The program is organized as a menu-driven application with a main loop at line 500–590. Navigation uses computed GOTO and GOSUB targets of the form M*VAL Z$, where M is a line-number multiplier constant. The major functional sections are:

Lines 500–590: Main menu and dispatch
Lines 1000–1090: Transistor file listing
Lines 1100–1298: Transistor data sheet input
Lines 1300–1430: Data sheet print/display
Lines 1450–1499: Section heading subroutines (one per category)
Lines 2000–2590: Amplifier design procedure (Q-point, component selection)
Lines 2900–2985: Standard component value rounding (section 6)
Lines 3000–3199: Q-point stability analysis with three beta values
Lines 3200–3890: Parametric sweep of Q-point vs. a chosen variable, graphical or tabular
Lines 4000–4990: Low-frequency / mid-band AC analysis and design
Lines 5000–5150: High-frequency response using Hybrid-Pi model
Lines 6000–6310: Standard component value selection
Lines 7000–7260: Schematic diagram display
Lines 8000–8090: Re-run analysis (section 8)
Lines 9000–9050 / 9997–9999: Variable editor using machine code

Constants and Named Line Numbers

The program uses a set of numeric variables as aliases for frequently-used constants and line numbers. This is a classic ZX81 BASIC memory optimization — storing a number in a variable and reusing the variable avoids re-parsing the literal each time. Key aliases inferred from usage include:

Variable	Value / Purpose
`N0`	0
`N1`	1
`N2`	2
`N3`	3
`N4`	4
`N5`	5
`N6`	6
`N7`	7
`N8`	8
`N9`	9
`O0`	10
`MM`	1,000,000 (mega/micro scaling)
`INF`	Very large number (used for infinite capacitance)
`M`	Menu section base line multiplier (e.g., 1000)
`H1`, `H5`, `P0`, `S1`, `S2`, `S3`, `S4`, `S5`, `BL`, etc.	Line number aliases for key subroutines and targets
`PI`	3.14159…
`KH`	Thermal voltage VT ≈ 0.026 V
`T0`	Reference temperature (°C or K)
`KT`	Thermal scaling constant for ICBO

Transistor Data Storage

Up to three transistor records are stored. Each record occupies a column in a two-dimensional numeric array X(parameter, file) and a string array Q$(file). The string array holds the part number (characters 1–8), polarity (NPN/PNP) at position N9, and device type (Si/Ge/Darlington) at position O0 (10). Parameter names and units are stored in the two-row string array X$(row, parameter), with row 1 being the label and row 2 being the units string. The section heading subroutines at lines 1450–1499 use a computed GOSUB 1449+C dispatch where C is the parameter index; this prints the correct section header at parameter boundaries without storing section membership explicitly.

Q-Point Iteration

The bias solution routine starting at line 3750 uses a fixed-point iteration loop. It begins with an estimated VBE and iterates the base current equation:

Computes IB and IQ from the resistor network equations
Detects saturation (line 3840) and cutoff (line 3860) as boundary cases
Updates VBE using the diode equation VBE = K1 + K2*LN(IQ) (lines 3827–3828)
Updates junction temperature TJ and leakage current ICB using ICBO*EXP(KT*(TJ-T0)) (lines 3832–3833)
Converges when both IQ and VQ change by less than tolerance ER
Aborts if iteration count exceeds KI, reporting “DIVERGED”

The tolerance ER is set differently for table mode (1/M) and graph mode (1/O1) at line 3756, trading accuracy for speed in the graphical sweep.

AC Small-Signal Analysis

The mid-band analysis at lines 4800–4990 (subroutine S5) uses composite H-parameters that incorporate the partially bypassed emitter resistor R4A. The effective parameters H21, H11, H12, H22 are derived from the device H-parameters (HFE, HIE, HRE, HOE) and R4A. Voltage gain AV, current gain AI, and power gain AP are computed from these. The input resistance RI is the parallel combination of R1, R2, and RBE.

The high-frequency analysis at lines 5000–5120 uses the Hybrid-Pi model. Transconductance GM = HFE/RBE, the Miller-multiplied input capacitance CIN = CBE + CBC*(1 + GM*(R4A+RO)), and the 3 dB frequency FH are computed analytically.

Low-frequency 3 dB corners are computed for all three capacitors (C1, C2, C3) independently at lines 4600–4620, which is an approximation (it ignores pole interaction) but is standard for a first-order design tool.

Graphical Parametric Sweep

Lines 3370–3641 implement a parametric sweep of Q-point versus a chosen variable (VBE, TA, BETA, R1, R2, R3, R4, VS). In graph mode, the display file base address is fetched via PEEK 16396 + 256*PEEK 16397 (line 3415), and individual character cells are written directly with POKE (lines 3054, 1300). Block graphic characters are used to plot IQ and VCE as separate traces on the same 32×21 character grid. The operating region (ACTIVE/SATURATED/NEAR CUTOFF/CUTOFF) is annotated, and an overload code character (computed at line 60 from four Boolean conditions: BVCE, IMAX, PMAX, TMAX) is printed alongside each data point.

Schematic Display

The ASCII schematic at line 7102 is a single large PRINT AT string containing block graphic escape sequences that draw the complete CE amplifier circuit, including transistor symbol, bias resistors R1/R2/R3/R4A/R4B, coupling capacitors C1/C3, bypass capacitor C2, load RL, and source RS. PNP transistors get an inverted symbol drawn at lines 7130–7144. Component values are overlaid on the schematic by the loop at lines 7010–7080 using the same coordinate lookup subroutine (GOSUB 25) that extracts AT row/column from the schematic string.

Machine Code Usage

Lines 9000–9050 implement an interactive variable editor. The program POKEs the display file (via POKE BL, N0/N1/N2) and then executes RAND USR VAL "9000" at line 9997, which calls a machine code routine. The editor prompt at line 9030 uses the syntax LET ?= NEW VAL, which is entered as a direct BASIC command to modify any variable. Line 9050 ends with RETURN , where is the block graphic for the character at code 76, used as a display marker. The GOTO VAL "9000" at line 9999 re-enters the main menu after the editor exits.

Standard Component Value Rounding

Lines 6000–6310 round computed component values to the nearest E6 or E12 series value. The program normalizes the value to the range [1, 10), finds the bounding E-series entries in array V(), and picks the closer one using the expression V(D+F*(C-V(D) >= V(D+F)-C)) — a compact way to select the nearer of two neighbors without an explicit conditional.

Unit Conversion and Display Formatting

The subroutine at lines 25–38 handles display of component values with automatic unit scaling. Resistances are shown in ohms or megohms; capacitances in picofarads or microfarads, with the threshold at 1E5 pF (0.1 µF). The string expressions ("PFD." AND Y$="C")+("OHMS" AND Y$="R") exploit the ZX81 BASIC behavior where AND with a true condition returns the left operand and with a false condition returns the empty string, enabling conditional string selection without IF statements.

Notable Idioms and Techniques

Computed GOSUB and GOTO targets using arithmetic on line-number variables avoid long IF/ELSE chains throughout
VAL "number" in GOTO/GOSUB is used as a memory-saving alternative to a literal line number
Boolean expressions in arithmetic context (N1 AND condition) are used pervasively for conditional assignment and string selection
The RR flag (re-run mode) suppresses interactive prompts and menu returns when sections are being called programmatically from section 8
SLOW/FAST switching is used strategically: FAST for computation-heavy loops, SLOW for interactive input and display
The convergence check at line 3820 uses ABS(I1-IQ) < ER/M AND ABS(V1-VQ) < ER, combining relative current and absolute voltage tolerances

Potential Anomalies

Line 13 contains LET ****=C — the variable name **** appears to be a placeholder or corruption in the listing; this would cause a syntax error unless the actual variable name was lost in transcription
Line 52–53 use escape sequences \!! and \;; which do not correspond to standard block graphic mappings and may represent inverse or special characters that were not captured correctly in the listing
The description states storage for five transistor files, but the code consistently uses file indices 1–3 (lines 1040, 1115, 1720), suggesting the description is inaccurate or refers to a different version
Line 57 uses PLOT with an expression involving R0, D, V, and E — PLOT on the ZX81 addresses the display file by character position, not pixel; this is likely intentional use of PLOT as a character-level plotting primitive consistent with the rest of the graphics approach

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Common-Emitter Transistor Amplifier

Design and analysis of common-emitter transistor amplifiers. Biasing, stability, frequency response, input/output resistances, power dissipation, and thermal effects taken into...

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Source Code
REM %C%E% %A%M%P--%1%:%2
GOTO H1
FOR B=N1 TO N4
POKE 16584+B,CODE Z$(B)
NEXT B
LET ****=C
RETURN 
FOR B=N1 TO N4
POKE 16650+B,CODE Z$(B)
NEXT B
LET C=****
RETURN 
LET Z$=C$(N1,A)+" "
GOSUB O0+(O0 AND O$<>"I")
LET Y$=Z$(N1)
GOSUB 32
LET D=CODE C$(N2,A,N1)
LET E=CODE C$(N2,A,N2)
RETURN 
IF Y$="C" THEN LET C=C*1E12
IF C>=1E5 THEN GOTO 37
LET Z$=("PFD." AND Y$="C")+("OHMS" AND Y$="R")
RETURN 
LET C=C/MM
LET Z$=("UFD." AND Y$="C")+("MEGOM" AND Y$="R")
RETURN 
LET R$=",,"
LET U$="~~"
GOTO N5*O0
LET R$=".."
LET U$="''"
GOSUB N6*O0
PRINT AT N1,A+N3;W$
IF Y/N2-INT (Y/N2)>N1/H1 THEN LET R$=U$
LET L=DF+33*(P1-INT (Y/N2))+A+N4
IF PEEK L=O0 AND R$=".." THEN LET R$="!!"
IF PEEK L=N9 AND R$="''" THEN LET R$=";;"
POKE L,CODE R$
IF Z$<>" VS " THEN RETURN 
IF A=N0 THEN RETURN 
PLOT N2*A+N6,R0*D/V+N2*A*(E-D)/V
RETURN 
LET W$=CHR$ (156+(VCE>BVCE)+N2*(IQ>IMAX)+N4*(PQ>PMAX)+N8*(TJ>TMAX))
IF W$="%0" THEN LET W$="-"
RETURN 
LET BP=(BETA+N1)/BETA
LET VDC=R4B*IQ*BP
LET VE=VDC+R4A*IQ*BP
LET VC=VE+VQ+RC*IQ
LET VCE=VC-VE
LET VMIN=RL*(R3*(VDC-VC)+(R4A+RC)*(VS-VC))/((R4A+RC+RL)*(RL+R3)-RL*RL)
LET VMAX=RL*(VS-VC)/(RL+R3)
RETURN 
LET R$=""
LET R$="VC  VE  VDC VCE VPP VMAXVMIN"+Z$
PRINT AT N4,N0;
FOR F=N1 TO LEN R$/N4
LET Z$=R$(F*N4-N3 TO F*N4)
GOSUB P0
IF Z$="IB  " OR Z$="ICB " THEN LET C=C*MM
PRINT Z$;TAB A*O0-N5;(STR$ C+E$)( TO N6)
NEXT F
RETURN 
LET Z=N0
CLS 
LET RR=N0
SLOW 
PRINT " ===%C%O%M%M%O%N-%E%M%I%T%T%E%R %T%R%A%N%S%I%S%T%O%R===",," =%A%M%P%L%I%F%I%E%R %A%N%A%L%Y%S%I%S %A%N%D %D%E%S%I%G%N=",,,"BY F.NACHBAUR",,"(C)1983",,
PRINT ,,TAB O1;"%M%A%I%N% %M%E%N%U",,," 1. INPUT/VIEW TRANSISTOR SPECS  2. DESIGN AMPLIFIER FROM SPECS  3. ANALYZE Q-POINT STABILITY    4. LOW FREQ/MID-BAND RESPONSE   5. HIGH FREQUENCY RESPONSE      6. STANDARD COMPONENT VALUES    7. SCHEMATIC DIAGRAM            8. RE-RUN ANALYSIS"( TO ((Z+N1)*32 AND Z<N5)+(243 AND Z>N4))
PRINT ,," NEXT STEP = ";Z+N1,"START OVER = 0",,," SAVE = S"," STOP = A"
LET Z$=INKEY$
IF Z$="" THEN GOTO 540
IF Z$="S" THEN SAVE     "C%E"
IF Z$="S" THEN GOTO 540
IF Z$<"0" OR Z$>"A" THEN GOTO H5
IF Z$="A" THEN STOP 
IF Z$<"6" THEN GOTO M*VAL Z$
GOSUB M*VAL Z$
GOTO H5
CLS 
PRINT T$;P$;" FILES",,,
PRINT TAB N5;"%F%I%L%E% %N%O","%T%R%A%N%S%I%S%T%O%R",,,
FOR A=N1 TO N3
PRINT ,,TAB N8;A,
PRINT Q$(A)( TO N8),,
PRINT "%P%O%L. ";Q$(A,N9);" : %T%Y%P%E ";Q$(A,O0)
NEXT A
IF RR THEN RETURN 
PRINT ,," RETURN TO MENU  :%M",,," INPUT DATA SHEET:%I",,," PRINT DATA SHEET:%P",,,"ANALYSIS/ DESIGN:%R"
SLOW 
IF INKEY$="" THEN GOTO 1075
LET Z$=INKEY$
GOTO (600 AND Z$="I")+(800 AND Z$="P")+(1400 AND Z$="R")+H5
GOTO 1075
GOSUB VAL "1700"
CLS 
PRINT AT O6,N0;" INPUT DATA IN UNITS SHOWN.",,,P$(N2 TO );" TAGGED ""*""-NOT VITAL.";AT P0-N1,N0;"% %V%B%L%     %U%N%I%T%S  %V%A%L%U%E",,,
PRINT "TYPE NUMBER?",
INPUT Q$(Q, TO N8)
PRINT Q$(Q, TO N8)
GOSUB S3
PRINT ,"%NPN/%PNP?"
LET Z$=INKEY$
IF Z$<>"N" AND Z$<>"P" THEN GOTO 1193
LET Q$(Q,N9)=Z$
PRINT AT P1,O6;"%GE/%SI/%DARL?"
LET Z$=INKEY$
IF Z$<>"G" AND Z$<>"S" AND Z$<>"D" THEN GOTO 1210
LET Q$(Q,O0)=Z$
PRINT AT P1,O6;E$;AT P1,O6;
GOSUB VAL "1650"
GOSUB S3
FOR C=N1 TO P4
GOTO 1250
LET C=C-N1
PRINT AT P0,N0;E$;E$
IF C<>N1 AND C<>N5 AND C<>N7 AND C<>15 AND C<>P1 THEN GOTO 1260
GOSUB S3
PRINT AT P0,N0;
GOSUB 1449+C
GOSUB S3
PRINT X$(N1,C);"  (";X$(N2,C);")","?";AT P1,O6;
INPUT Z$
IF Z$="" AND (C=N6 OR C=O0 OR C=O6-N1 OR C=P1) THEN LET Z$="."
IF Z$="" THEN GOTO VAL "1265"
IF Z$="E" THEN GOTO VAL "1245"
LET X(C,Q)=VAL Z$
PRINT Z$;
IF C=O1 OR C=O3 THEN PRINT "  AT "
GOSUB S3
IF C=P1 AND Z$<>"." THEN LET C=P1+N1
NEXT C
GOSUB S2
LET Z=N1
GOTO M
POKE BL,N0
GOSUB VAL "1700"
GOSUB S1
CLS 
PRINT AT N0,N0;"%T%Y%P%E:";Q$(Q, TO N8),
GOSUB VAL "1650"
FOR C=N1 TO P4
GOSUB 1449+C
PRINT X$(N1,C);(STR$ X(C,Q)+E$)( TO N4);X$(N2,C);" :";
IF C=P1 AND X(C,Q)<>N0 THEN LET C=P1+N1
NEXT C
GOSUB S2
GOTO M
PRINT ,,TAB N3;"%A%B%S%O%L%U%T%E% %M%A%X%I%M%U%M% %R%A%T%I%N%G%S"
RETURN 
PRINT ,,TAB N9;"%T%H%E%R%M%A%L% %C%H%A%R%."
RETURN 
PRINT ,,TAB N7;"%D%C% %C%H%A%R%A%C%T%E%R%I%S%T%I%C%S"
RETURN 
PRINT ,,TAB N3;"%L%F% %S%M%A%L%L%-%S%I%G%N%A%L% %P%A%R%A%M%E%T%E%R%S"
RETURN 
PRINT ,,TAB N2;"%H%F% %E%Q%U%I%V%A%L%E%N%T% %C%I%R%C%U%I%T% %V%A%L%U%E%S"
RETURN 
PRINT "%P%L%E%A%S%E% %S%T%A%N%D% %B%Y:"
FAST 
PAUSE H1
RETURN 
SCROLL 
PRINT AT P1,P1+O0;" ";AT P1,N0;
RETURN 
POKE BL,N0
SLOW 
PRINT AT P3,N0;" TO COPY - %Z : CONT - %C"
POKE BL,N1
IF INKEY$="Z" THEN COPY 
POKE BL,N2
IF INKEY$="C" THEN RETURN 
GOTO S2+N5
PRINT "%P%O%L. ";Q$(Q,N9);" : %T%Y%P%E ";Q$(Q,O0)
RETURN 
PRINT AT P1,N0;"WHICH FILE? %1-%3   "
LET Z$=INKEY$
IF Z$<"1" OR Z$>"3" THEN GOTO VAL "1710"
LET Q=VAL Z$
RETURN 
GOSUB VAL "1700"
CLS 
PRINT T$;"USED - ";Q$(Q)( TO N8),,
GOSUB VAL "1650"
GOSUB S1
FOR A=N1 TO P4
LET C=X(A,Q)*O0**(N6*(X$(N2,A,N1)="M"))*O0**(-N6*(X$(N2,A,N1)="U"))*O0**(-12*(X$(N2,A,N1)="P"))
LET Z$=X$(N1,A)
GOSUB O0
NEXT A
IF NOT KH THEN LET KH=VAL ".026"
IF NOT VBES THEN LET VBES=.8*(Q$(Q,O0)="S")+.3*(Q$(Q,O0)="G")+1.5*(Q$(Q,O0)="D")
LET RC=VCES/ISAT
SLOW 
IF RR THEN RETURN 
PRINT AT N2,N0;E$," INPUT EXT. CIRCUIT";P$,,,"SUPPLY VLTG.","VS=";
SLOW 
INPUT VS
PRINT VS,,,"LOAD RES.(OHMS) RL=";
INPUT RL
PRINT RL,,,"SOURCE  RES.    RS=";
INPUT RS
PRINT RS
GOSUB S2
CLS 
PRINT ,,"%S%E%L%E%C%T% %M%O%D%E - %ANALYSIS/%DESIGN"
LET M$=INKEY$
GOTO (810 AND M$="A")+(O0 AND M$="D")+2090
CLS 
PRINT TAB N7;"%D%E%S%I%G%N% %P%R%O%C%E%D%U%R%E"
PRINT "SPECIFY %OUTPUT SWING OR %Q-POINT?"
LET N$=INKEY$
GOTO 2105+(15 AND N$="O")+(25 AND N$="Q")
PRINT AT N1,N0;"DESIRED OUTPUT SWING? VP=";E$
INPUT VP
PRINT AT N1,P7;VP
GOTO VAL "2140"
PRINT AT N1,N0;"Q-POINT:VQ=";E$;E$
INPUT VQ
PRINT AT N1,O1;VQ;TAB N8;"IQ=";
INPUT IQ
PRINT IQ
PRINT "DC STABILITY (R4/R3)=SF1=";
INPUT SF1
PRINT SF1
LET R4A=N0
LET BETA=BTYP
IF N$="O" THEN GOTO VAL "2200"
LET R3=((VS-VQ)/IQ-RC)/(N1+SF1)
LET R4B=SF1*R3
GOSUB N7*O0
GOTO VAL "2400"
GOSUB S1
PRINT AT N3,N0;E$
LET R3=M
LET VQ=VS/N2
LET R4B=SF1*R3
LET IQ=(VS-VQ)/(RC+R3+BP*R4B)
GOSUB O0*N7
LET VPP=VMAX-VMIN
LET C=N2*VPP/(VP+VPP)
IF ABS (C-N1)<1E-4 THEN GOTO VAL "2400"
IF R3<N1 THEN GOTO VAL "2350"
LET R3=R3*C
LET VQ=VPP/N2+RC*(VS-VDC)/(RC+R3)
GOTO 2205
PRINT "NO SOLUTION: VP/VS TOO HIGH"
GOSUB S2
GOTO VAL "2100"
LET Z$="R3  R4B VQ  IQ  "
LET A=N2
GOSUB N8*O0
SLOW 
PRINT ,,"RE-DO? %Y/%N"
GOTO 2490+(O0 AND INKEY$="N")-(390 AND INKEY$="Y")
LET VBE=VBES
PRINT " INPUT R1:"
INPUT R1
LET VB=VBE+VE
LET R2=(VS-VB)/(IQ/BETA+VB/R1)
LET C1=INF
LET C2=C1
LET C3=C1
LET Z=N2
FAST 
GOSUB N7*M
GOTO VAL "2975"
GOSUB VAL "7100"
PRINT AT N0,N0;" INPUT IN STANDARD UNITS(OHMS/FD)"
FOR A=N1 TO N8
GOSUB 25
PRINT AT D,E;"%??%??%?";TAB E;(STR$ C+E$)( TO N5)
SLOW 
INPUT C
FAST 
LET O$="I"
GOSUB 25
LET O$=""
PRINT AT D,E;(STR$ C+E$)( TO N5);TAB E;Z$;" "
NEXT A
LET Z=N2
GOSUB S2
LET OCA=N0
LET TA=-H5
CLS 
LET R4=R4A+R4B
LET K2=KH
LET K1=VBES-K2*LN ISAT
PRINT TAB N6;"%Q%-%P%O%I%N%T / %P%O%W%E%R% %D%I%S%S."
IF TA<>-H5 THEN GOTO 3030
PRINT AT N2,N0;"AMBIENT TEMP TA=";
INPUT TA
IF DRTF=N0 THEN GOTO 3070
PRINT AT N2,N0;"%FREE AIR OR %HEAT-SINKED?"
GOTO (P0 AND INKEY$="H")+(O0 AND INKEY$="F")+3050
LET OCA=N1/DRTF-OJC
GOTO 3100
PRINT AT N2,N0;"TH. RES. CASE-AMB=";E$;
INPUT OCA
PRINT AT N1,N0;"OCA=";OCA;AT N2,O6;E$;AT N2,N0;
GOSUB S1
PRINT AT N2,N0;"   %M%I%N.%B%E%T%A  %T%Y%P.%B%E%T%A  %M%A%X.%B%E%T%A";AT O6+N2,N0;"%R%E%G%I%O%N:",,,,"%V/%I/%P/%T:"
LET KT=N1/O3
IF Q$(Q,O0)="S" THEN LET KT=N1/P0
FOR A=N1 TO N3
LET BETA=(BMIN AND A=N1)+(BTYP AND A=N2)+(BMAX AND A=N3)
PRINT AT N3,A*O0-N4;"=";BETA
LET Y$="T"
GOSUB S4
IF IT<=KI THEN GOTO 3140
PRINT AT N5,A*O0-N7;"%D%I%V%E%R%G%E%D-"
GOTO VAL "3194"
GOSUB N7*O0
LET Z$="VB  VBE IB  ICB IQ  PQ  TJ  "
GOSUB N8*O0
LET R$="ACTIVE"
IF VQ=N0 THEN LET R$="SATUR""D"
IF VQ>.9*VS THEN LET R$="NR CTOFF"
IF VQ=VS THEN LET R$="CUTOFF"
PRINT AT O9,A*O0-N7;R$
GOSUB N6*O0
PRINT AT P1,A*O0-N7;
IF W$="-" THEN PRINT "  OK"
IF W$<>"-" THEN PRINT "B/O-CODE";W$
NEXT A
LET BETA=BTYP
PRINT AT O3,P1+N1;"%U%A";TAB P1+N1;"%U%A"
GOSUB S4
GOSUB N7*O0
GOSUB S2
CLS 
SLOW 
PRINT AT N0,N0;"%C%H%A%N%G%E% %A% %V%B%L%? Y/N"
IF INKEY$="Y" THEN GOSUB 9000
IF INKEY$<>"N" THEN GOTO 3202
PRINT AT N0,N0;"%E%X%T%R%E%M%A%L% %B%I%A%S"
IF INKEY$<>"" THEN GOTO 3210
IF INKEY$="" THEN GOTO 3212
IF INKEY$="Y" THEN GOTO 3230
IF RR THEN RETURN 
LET Z=N3
GOTO H5
PRINT AT N0,O3;E$,,,"%GRAPH OR %TABLE?"
LET Y$=INKEY$
IF Y$<>"G" AND Y$<>"T" THEN GOTO 3232
LET R$=" VS VBE  TA BETA R1  R2  R3  R4 "
PRINT AT N2,N0;" RUN VQ/IQ VERSUS WHICH VBL?",,,R$,,
FOR A=N1 TO N8
PRINT " ";CHR$ (A+156);"  ";
NEXT A
LET A=CODE INKEY$-28
IF A<N1 OR A>N8 THEN GOTO 3280
LET Z$=R$(N4*A-N3 TO N4*A)
PRINT ,,Z$;
GOSUB P0
GOSUB O0
PRINT "=";C
LET G=C
PRINT "MIN. VALUE=",
INPUT D
PRINT D,"MAX. VALUE=",
INPUT E
PRINT E
LET V=VS
IF Z$=" VS " THEN LET V=E
LET W=VS/(R4+RC+R3)
IF Z$=" VS " THEN LET W=E/(R4+RC+R3)
IF Z$=" R4 " THEN LET W=VS/(D+R3+RC)
IF Z$=" R3 " THEN LET W=VS/(D+RC+R4)
GOSUB S1
CLS 
POKE BL,N0
IF Y$="T" THEN GOTO 3450
PRINT AT N4,P4;"OJA=";TAB P4;(STR$ (OCA+OJC)+E$)( TO N8)
FOR A=N0 TO P0
LET R$=CHR$ (P7-N4*(A/N5=INT (A/N5)))
PRINT AT A+N1,N3;R$;TAB P3;R$;AT P1,A+N3;R$
NEXT A
PRINT AT N0,N0;" VQ.. EXC. V/I/P/T CODE ,,IQ","VS-";TAB P4;"-ISAT=",V;TAB P4;(STR$ W+E$)( TO N8)
PRINT AT P1,N1;"0-";TAB P4;"-0";TAB N2;D;TAB O0;Z$;TAB P1;E
LET DF=PEEK 16396+256*PEEK 16397
GOTO 3500
PRINT "%  ";Z$;" % %V%(%C%E%)% %I%(%Q%)% % %P%(%Q%)% % %T%(%J%)% % "
LET R$=""
FOR A=N0 TO P0
LET C=D+A*(E-D)/P0
GOSUB O3
GOSUB S4
IF Y$="G" THEN GOTO 3558
GOSUB N6*O0
PRINT AT A+N1,N0;W$;(STR$ C+" ----")( TO N6);"% ";
IF IT<=KI THEN PRINT (STR$ VCE+E$)( TO N5);"% ";(STR$ IQ+F$)( TO N5);"% ";(STR$ PQ+F$)( TO N5);"% ";(STR$ TJ+F$)( TO N5);"% "
IF IT>KI THEN PRINT "=====INDETERMINATE=====% "
GOTO 3640
IF IT<=KI THEN GOTO 3565
LET R$=CHR$ (137+(A/N2=INT (A/N2)))
FOR B=N2 TO P0
PRINT AT B,A+N3;R$
NEXT B
GOTO 3640
LET Y=INT (R0*IQ/W+N1/N2)
GOSUB R0
LET Y=INT (R0*VCE/V+N1/N2)
GOSUB R0+N3
PAUSE H1
NEXT A
IF Y$="G" THEN GOTO 3645
PRINT "MAX V/I=";V;"/";W
LET C=G
GOSUB O3
GOSUB S4
GOSUB S2
GOTO VAL "3200"
LET IT=N0
LET BP=(BETA+N1)/BETA
LET PQ=N0
LET ER=(N1/M AND Y$="T")+(N1/O1 AND Y$="G")
IF Z$<>"VBE " THEN LET VBE=VBES
LET ICB=ICBO
LET VBB=VS*R1/(R1+R2)
LET RBB=N1/(N1/R1+N1/R2)
LET V1=VS/N2
LET I1=V1/(R4+R3+RC)
LET IB=(VBB-VBE-BETA*ICB*R4)/(RB+RBB+R4*(BETA+N1))
IF IB+ICB<N0 THEN GOTO 3860
LET IQ=BETA*(IB+ICB)
LET VQ=VS-IQ*(RC+R3+BP*R4)
IF VQ<N0 THEN GOTO 3840
IF ABS (I1-IQ)<ER/M AND ABS (V1-VQ)<ER THEN GOTO 3870
IF INKEY$="Y" THEN LET IT=KI
LET IT=IT+N1
IF IT>KI THEN RETURN 
IF Z$<>"VBE " THEN LET VBE=K1+K2*LN IQ
IF VBE>VBB THEN LET VBE=VBB
LET VCE=VQ+RC*IQ
LET PQ=VCE*IQ+(IB+ICB)*VBE
LET TJ=TA+PQ*(OJC+OCA)
LET ICB=ICBO*EXP (KT*(TJ-T0))
LET V1=VQ
LET I1=IQ
GOTO 3800
REM %S%A%T
LET IB=((VBB-VBE)*(R3+RC+R4)-VS*R4)/((RBB+RB+R4)*(RC+R3+R4)-R4*R4)
IF IB+ICBO<=N0 THEN GOTO 3860
LET IQ=(VS*(RBB+RB+R4)-R4*(VBB-VBE))/((RBB+RB+R4)*(RC+R3+R4)-R4*R4)
LET VQ=N0
GOTO 3820
REM %C%O
LET IB=-ICB
LET IQ=ICB
GOTO 3810
LET VE=R4*IQ
LET VB=VBE+RB*IB+VE
LET VC=VE+VCE
RETURN 
CLS 
LET RO=(RC+R3)*RL/(RC+R3+RL)
IF M$="A" THEN GOTO 4500
FAST 
PRINT "%A%C% %V%O%L%T%A%G%E% %G%A%I%N"
LET R4A=N0
LET HFE=HMIN
GOSUB S5
PRINT "MAX. AV AT HMIN =";AV
LET R4A=R4
LET HFE=HMAX
GOSUB S5
PRINT "MIN. AV AT HMAX =";AV
PRINT "%D%E%S%I%R%E%D% %A%V =";
INPUT AD
PRINT AD
LET HFE=HTYP
LET R4A=R4/N2
GOSUB S5
IF ABS ((AV-AD)/AD)<N1/M THEN GOTO 4280
IF H21*R4A<H11/100 OR R4A>R4 THEN GOTO 4260
LET R4A=R4A*(AV/AD)
GOTO 4220
PRINT ,,"NO SOLUTION"
GOSUB S2
GOTO N4*M
LET R4B=R4-R4A
GOSUB N7*O0
LET A=N1
LET Z$="R4A R4B R4  "
GOSUB N8*O0
GOSUB S2
CLS 
PRINT "%S%P%E%C%I%F%Y% %L%F% %3% %D%B% %C%O%R%N%E%R%S:"
PRINT ,,"INPUT COUPLING:",
INPUT FL1
PRINT FL1,,,"EMITTER BYPASS:",
INPUT FL2
PRINT FL2,,,"OUTPUT COUPLING",
INPUT FL3
PRINT FL3
GOSUB S1
LET C1=N1/(N2*PI*FL1*(RS+RI))
LET C2=N1/(N2*PI*FL2*R4B)
LET C3=N1/(N2*PI*FL3*(RL+R3/HOE/(R3+N1/HOE)))
GOSUB N7*M
LET M$="A"
GOTO N4*M
GOSUB S1
CLS 
PRINT "%P%A%S%S%B%A%N%D/%L%F% %R%E%S%P%O%N%S%E"
PRINT ,,"   %M%I%N.%H%F%E%   %T%Y%P.%H%F%E%   %M%A%X.%H%F%E% "
FOR A=N1 TO N3
LET HFE=(HMIN AND A=N1)+(HTYP AND A=N2)+(HMAX AND A=N3)
PRINT AT N3,A*O0-N4;"=";HFE
GOSUB S5
LET FL1=N1/(N2*PI*C1*(RS+RI))
LET FL2=N1/(N2*PI*C2*R4B)
LET FL3=N1/(N2*PI*C3*(RL+R3/HOE/(R3+N1/HOE)))
LET APDB=O0*LN AP/LN O0
LET R$="FL1 FL2 FL3 AV  AI  AP  APDBRI  "
GOSUB 82
NEXT A
LET HFE=HTYP
GOSUB S5
GOSUB S2
IF RR THEN RETURN 
LET Z=N4
GOTO H5
LET HIE=RB+HFE*KH/(IQ+IB)
IF R4A=N0 THEN LET R4A=1/INF
LET H21=HFE+HOE*(HFE+N1)/(HOE+N1/R4A)
LET H11=HIE+R4A*(N1+H21)+HRE*(HFE+N1)/(HOE+N1/R4A)
LET H12=(R4A*HOE+HRE)/(R4A*HOE+N1)
LET H22=HOE/(R4A*HOE+N1)
LET RBE=H11/(N1+(H21*H12)/(H11*H22-H21*H12+H11/RO))
LET RI=N1/(N1/R1+N1/R2+N1/RBE)
LET AV=(-H21/(H11*H22-H21*H12+H11/RO))*RI/(RI+RS)
LET AI=(H21/(N1+H22*RO))*(R3+RC)/(R3+RC+RL)
LET AP=ABS (AI*AV)
RETURN 
CLS 
PRINT "%H%F% %R%E%S%P%O%N%S%E"
LET HFE=HTYP
LET GM=HFE/RBE
IF X(P1,Q)=N0 THEN GOTO 5100
LET CBE=GM/(N2*PI*FT)
LET CIN=CBE+CBC*(N1+GM*(R4A+RO))
LET FH=(HFE+GM*(RB+RS)+GM*R4A*(N1+HFE))/(N2*PI*HFE*(R4A+RB+RS)*CIN)
PRINT ,,"C(IN)=",CIN*MM*MM;" PF",,,"F(3DB)=",FH/MM;" MHZ"
GOSUB S2
IF RR THEN RETURN 
LET Z=N5
GOTO H5
CLS 
PRINT "5 OR 10 '/. ?",,"(1)  (2)"
INPUT F
IF F<N1 OR F>N2 THEN GOTO 6005
GOSUB S1
FOR A=N1 TO N8
LET Z$=C$(N1,A)+" "
GOSUB P0
LET E=N0
GOTO 6200+(H1 AND C=N0)-(H1 AND C<=N1 AND C<>N0)-(H1/N2 AND C>O0)
LET C=C*O0
LET E=E-N1
GOTO 6050
LET C=C/O0
LET E=E+N1
GOTO 6050
LET D=N1
IF C>=V(D) AND C<=V(D+F) THEN GOTO 6250
LET D=D+F
GOTO 6210
LET C=O0**E*V(D+F*(C-V(D)>=V(D+F)-C))
GOSUB O0
NEXT A
LET Z=N7
GOSUB VAL "7100"
FOR A=N1 TO N8
GOSUB 25
PRINT AT D,E;(STR$ C+E$)( TO N5);TAB E;Z$;" "
NEXT A
GOSUB S2
RETURN 
CLS 
PRINT AT N0,N0;"DC AND LF SCHEMATIC DIAGRAM - CE      :''''''''''''''':''''''''''''''''''''''''''''''':        :        :     %T%R%A%N%S%I%S%T%O%R::        :        '. R3            :  %I%N%P%U%T :        '.               :        '. R2    '.      %O%U%T%P%U%T   :    C1  '.       '.  . .            :        '.       :....: :......% <...      :        '.    .. .'   : :      :      :     . .  :     % .'  C3       :      : + .%>.: :....:.........%          R  .'      :   :  : :  :     % .          L .'   V '''''  :     :     %  '.:          .'    S '''  :R    :       '''.          .'     ''''' '. S   .' R1    '. R4A     :      ':' '.     .'       '.         :      : -'.     .'       '.         :      :  '.     .'       :.....'.'.'.'...  :      :  .:.     :    C2  :    R4B :  :      :  :.: V   :       '''''       :  :      :   : IN  :       '':''       :  :      :   ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''  "
PRINT AT N3,P1;Q$(Q)( TO N8)
IF Q$(Q,N9)="N" THEN GOTO 7150
PRINT AT O1+N1,O1+N1;" ::'";TAB O1+N1;" ' '"
PRINT AT N9,P9+N2;"-";AT O6-N1,P9+N2;"+"
PRINT AT O6-N1,P0+N5;(STR$ VS+E$)( TO N4);TAB P0+N5;"VOLTS"
LET C=RL
LET Y$="R"
GOSUB 32
PRINT AT O0+N2,P0-N2;(STR$ C+E$)( TO N5);TAB P0-N2;Z$
LET C=RS
GOSUB 32
PRINT AT 15,N1;(STR$ C+E$)( TO N5);TAB N1;Z$
RETURN 
CLS 
LET RR=N1
GOSUB M
GOSUB VAL "1700"
GOSUB N2*M
CLS 
IF Z>N2 THEN GOSUB VAL "3010"
IF Z>N3 THEN GOSUB N4*M
IF Z>N4 THEN GOSUB N5*M
RETURN 
FAST 
GOSUB N7*M
POKE BL,N0
SLOW 
PRINT AT P3-N1,N0;" LET ?= NEW VAL ,  RETURN OR CONT ";E$;"%Y"
POKE 16384,89
RETURN 76
RAND USR VAL "9000"
GOTO VAL "540"

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