Version 4.1
SHEET 1 2184 1468
WIRE -144 224 -240 224
WIRE 80 224 -64 224
WIRE 96 224 80 224
WIRE 496 224 96 224
WIRE -240 256 -240 224
WIRE 96 272 96 224
WIRE 496 336 496 224
WIRE -240 368 -240 336
WIRE 96 384 96 352
WIRE 144 384 96 384
WIRE 288 384 144 384
WIRE 432 384 368 384
WIRE 96 416 96 384
WIRE 496 464 496 432
WIRE -400 560 -448 560
WIRE -256 560 -320 560
WIRE 96 560 96 480
WIRE 96 560 -256 560
WIRE 496 560 496 544
WIRE 752 560 496 560
WIRE 800 560 752 560
WIRE 496 592 496 560
WIRE 752 592 752 560
WIRE -448 624 -448 560
WIRE 96 640 96 560
WIRE 496 704 496 672
WIRE 752 720 752 672
WIRE -448 752 -448 704
WIRE -208 752 -272 752
WIRE 96 752 96 704
WIRE 160 752 96 752
WIRE 272 752 160 752
WIRE 432 752 352 752
WIRE -272 768 -272 752
WIRE -208 800 -208 752
WIRE 96 800 96 752
WIRE -208 912 -208 880
WIRE -80 912 -208 912
WIRE 96 912 96 880
WIRE 96 912 0 912
WIRE 496 912 496 800
WIRE 496 912 96 912
FLAG 800 560 output
FLAG -256 560 input
FLAG 80 224 Vsupply
FLAG 144 384 Q1_base
FLAG -448 752 0
FLAG -240 368 0
FLAG -272 768 0
FLAG 752 720 0
FLAG 160 752 Q2_base
SYMBOL res 80 256 R0
SYMATTR InstName R1
SYMATTR Value 500R
SYMBOL npn 432 336 R0
SYMATTR InstName Q1
SYMATTR Value ZXT849K
SYMBOL res 480 448 R0
SYMATTR InstName R_Q1_emmitter
SYMATTR Value 0.1R
SYMBOL voltage -240 240 R0
SYMATTR InstName V1
SYMATTR Value 15V
SYMBOL voltage -448 608 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
WINDOW 3 42 56 Left 2
SYMATTR Value SINE(0 10 100k)
SYMATTR InstName V3
SYMBOL pnp 432 800 M180
SYMATTR InstName Q2
SYMATTR Value ZXT951K
SYMBOL diode 80 416 R0
SYMATTR InstName D1
SYMBOL diode 80 640 R0
SYMATTR InstName D2
SYMBOL res 480 576 R0
SYMATTR InstName R_Q2_emmitter
SYMATTR Value 0.1R
SYMBOL voltage -208 784 R0
SYMATTR InstName V2
SYMATTR Value 15V
SYMBOL res -416 544 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R_source
SYMATTR Value 100R
SYMBOL res 80 784 R0
SYMATTR InstName R3
SYMATTR Value 500R
SYMBOL res 736 576 R0
SYMATTR InstName R_load
SYMATTR Value 5R
SYMBOL res -160 208 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R_Isense_P
SYMATTR Value 1m
SYMBOL res 16 896 R90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R_Isense_N
SYMATTR Value 1m
SYMBOL res 272 368 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R_Q1_base
SYMATTR Value 1m
SYMBOL res 256 736 M90
WINDOW 0 0 56 VBottom 2
WINDOW 3 32 56 VTop 2
SYMATTR InstName R_Q2_base
SYMATTR Value 1m
TEXT -232 -528 Left 6 ;class B Amplifier
TEXT -592 184 Left 2 !.tran 0 0.1m 0
TEXT -432 -312 Left 4 ;Instructions
TEXT -536 -280 Left 2 ;click on run\nthen click on "input" to plot it.\nthen click on the plot window then on plot settings / add plot pane\nthen click on "output" to plot it\nthen click on the plot window and plot settings/add plot pane\nthen hold the ALT key hover over R-Load and click, \nthis will plot the power dissipated in it.\nclick on the plot window, then hold the cntrl key and click on the \n"V(output)*I(R_load)" title\nthis will bring up its average value (about 6W).\nthen click on the plot window and plot settings/add plot pane\nthen hover the mouse over "R_Isense_P" to plot its current\nclick on the plot window, then hold the cntrl key and click on the \n"I(R_Isense_P)" title this will bring up its average value (about 0.6A).\ncalculate input power as 2 x 15V x the above 0.6A... this gives about 18W.\nthis means this class B amplifier is 33% efficient in this example.
TEXT -352 -464 Left 3 ;The output voltage is the same as the input Voltage, so this is not a voltage amplifier,\nhowever the output is capable of driving much more current then the input.\nSome people would call this a buffer rather than an amplifier.
TEXT 376 -304 Left 4 ;Circuit description
TEXT 360 -248 Left 2 ;In the instructions text block, the eficiency \nof this circuit has been calaculated as 33%.\nThis is better than a class A (eg cm emmitter) amplifier.\nbut not as good as a Class C, or Class D amplifier.\nHowever this amplifier is linear, class C and Class D are not.\n \nQ1 and Q2 have been chosen to have similar min hfe characteristics.\nthe transistor models in the black text at the bottom \nhave Hfe (they call it BF) values of 230 and 187,\nbut their datasheet min hfe is 100, \n \nIf building this cct go to Rohm devices in Dpak with min hfe =200,\neg...2SCR572D3FRATL (NPN), and 2SAR572D3TL1 (PNP)\nboth devices are 300Mhz, 30V, min Hfe 200, DPAK.
TEXT -448 968 Left 2 !*DIODES_INC_SPICE_MODEL\n*\n.MODEL ZXT849K NPN IS =5.8591E-13 NF =0.9919 BF =230 IKF=18 VAF=90\n+ ISE=2.0067E-13 NE =1.4 NR =0.9908 BR =180 IKR=6.8 \n+ VAR=20 ISC=5.3E-13 NC =1.46 RB =0.023 RE =0.0223 \n+ RC =0.015 CJC=200E-12 MJC=0.3006 VJC=0.3532 \n+ CJE=1.21E-9 TF =1.07E-9 TR =9.3E-9
TEXT 488 960 Left 2 !.MODEL ZXT951K PNP IS=1.3766E-12 NF=1.013 BF=187 IKF=5.0 VAF=66.3\n+ ISE=1.4E-13 NE=1.41 NR=1.0099 BR=56 IKR=0.9 VAR=33 ISC=1.7E-12\n+ NC=1.4 RB=0.029 RE=0.020 RC=0.0255 CJC=287E-12 MJC=0.4522 \n+ VJC=0.4956 CJE=1.15E-9 TF=0.83E-9 TR=20E-9
TEXT 440 1088 Left 1 ;You may republish or reuse this circuit implementation and text providing this line and the following lines are included.\nThis circuit implementation designed by Keith Wallbanks., Originally released on analogsimulation.co.uk\nThis circuit is provided as is without warranty of any kind. This text is intended to implement the MIT licence.