* SPICE netlist
Q1 0 var N008 0 PNP
Q2 N013 ref N008 0 PNP
R1 N001 N008 3.3k
R2 N013 0 10k
R3 ref 0 {(1-VV)*10k}
R4 N009 ref {VV*10k}
R5 N002 N001 2.2k
D1 0 N009 z10
D2 N009 N001 z24
V1 N002 0 SINE(40 0 60)
C1 N001 0 10
Q3 N005 N013 0 0 NPN
R6 N002 N005 100k
Q4 N003 N005 N007 0 NPN
Q5 N004 N003 N002 0 PNP
Q6 N002 N004 out 0 NPN
D3 N007 out D
RLOAD out N012 {LOAD}
R11 N012 0 0.1
R9 out var 0.1
R10 var 0 8.2k
C2 N005 0 4.7
Q7 N010 N012 N014 0 NPN
Q8 N011 0 N014 0 NPN
RLOAD1 N014 N015 3.3k
R8 N001 N010 10k
R12 N001 N011 10k
V2 0 N015 2.4
.tran 100m
.param VV 0.52
.param CC 0.4
.step param LOAD .5 2 .5

* LTspice schematic (.asc)
Version 4
SHEET 1 1968 1024
WIRE 792 -512 -424 -512
WIRE -664 -448 -984 -448
WIRE -152 -448 -664 -448
WIRE 264 -448 -152 -448
WIRE 424 -448 264 -448
WIRE 264 -416 264 -448
WIRE -152 -400 -152 -448
WIRE 200 -368 168 -368
WIRE 424 -368 424 -448
WIRE -664 -352 -664 -448
WIRE 360 -320 264 -320
WIRE 168 -288 168 -368
WIRE -152 -240 -152 -320
WIRE 104 -240 -152 -240
WIRE 424 -240 424 -272
WIRE -664 -176 -664 -272
WIRE -664 -176 -904 -176
WIRE -424 -176 -424 -512
WIRE -424 -176 -664 -176
WIRE 792 -160 792 -512
WIRE 792 -160 728 -160
WIRE 856 -160 792 -160
WIRE -424 -144 -424 -176
WIRE -664 -128 -664 -176
WIRE 168 -128 168 -192
WIRE 264 -128 168 -128
WIRE 424 -128 424 -160
WIRE 424 -128 328 -128
WIRE 728 -48 728 -160
WIRE 856 -48 856 -160
WIRE -424 -32 -424 -64
WIRE -424 -32 -504 -32
WIRE -344 -32 -424 -32
WIRE -984 -16 -984 -448
WIRE 424 -16 424 -128
WIRE -504 16 -504 -32
WIRE -344 16 -344 -32
WIRE -664 32 -664 -64
WIRE -664 32 -776 32
WIRE -568 64 -584 64
WIRE 8 64 -280 64
WIRE 136 64 8 64
WIRE 200 64 136 64
WIRE 424 64 424 -16
WIRE 424 64 280 64
WIRE -664 80 -664 32
WIRE -584 96 -584 64
WIRE -152 96 -152 -240
WIRE -88 96 -152 96
WIRE 728 96 728 32
WIRE 856 96 856 32
WIRE -152 128 -152 96
WIRE 424 144 424 64
WIRE 664 144 584 144
WIRE 984 144 920 144
WIRE -504 176 -504 112
WIRE -216 176 -504 176
WIRE -664 192 -664 160
WIRE -584 192 -584 96
WIRE -584 192 -664 192
WIRE 136 192 136 64
WIRE -664 208 -664 192
WIRE -504 208 -504 176
WIRE -904 224 -904 -176
WIRE -776 224 -776 32
WIRE -88 224 -88 96
WIRE 728 224 728 192
WIRE 792 224 728 224
WIRE 856 224 856 192
WIRE 856 224 792 224
WIRE 984 224 984 144
WIRE 792 256 792 224
WIRE -984 336 -984 64
WIRE -904 336 -904 288
WIRE -904 336 -984 336
WIRE -776 336 -776 288
WIRE -776 336 -904 336
WIRE -664 336 -664 288
WIRE -664 336 -776 336
WIRE -504 336 -504 288
WIRE -504 336 -664 336
WIRE -344 336 -344 112
WIRE -344 336 -504 336
WIRE -152 336 -152 224
WIRE -152 336 -344 336
WIRE -88 336 -88 288
WIRE -88 336 -152 336
WIRE 136 336 136 272
WIRE 136 336 -88 336
WIRE 296 336 136 336
WIRE 424 336 424 224
WIRE 424 336 376 336
WIRE 584 336 584 144
WIRE 584 336 424 336
WIRE -984 400 -984 336
WIRE 792 400 792 336
WIRE 792 512 792 480
FLAG -984 400 0
FLAG 424 -16 out
FLAG 8 64 var
FLAG -584 96 ref
FLAG 984 224 0
FLAG 792 512 0
SYMBOL pnp -280 112 R180
SYMATTR InstName Q1
SYMBOL pnp -568 112 M180
SYMATTR InstName Q2
SYMBOL res -440 -160 R0
SYMATTR InstName R1
SYMATTR Value 3.3k
SYMBOL res -520 192 R0
SYMATTR InstName R2
SYMATTR Value 10k
SYMBOL res -680 192 R0
SYMATTR InstName R3
SYMATTR Value {(1-VV)*10k}
SYMBOL res -680 64 R0
SYMATTR InstName R4
SYMATTR Value {VV*10k}
SYMBOL res -680 -368 R0
SYMATTR InstName R5
SYMATTR Value 2.2k
SYMBOL zener -760 288 R180
SYMATTR InstName D1
SYMATTR Value z10
SYMBOL zener -648 -64 R180
SYMATTR InstName D2
SYMATTR Value z24
SYMBOL voltage -984 -32 R0
SYMATTR InstName V1
SYMATTR Value SINE(40 0 60)
SYMBOL polcap -920 224 R0
SYMATTR InstName C1
SYMATTR Value 10u
SYMBOL npn -216 128 R0
SYMATTR InstName Q3
SYMBOL res -168 -416 R0
SYMATTR InstName R6
SYMATTR Value 100k
SYMBOL npn 104 -288 R0
SYMATTR InstName Q4
SYMBOL pnp 200 -320 M180
SYMATTR InstName Q5
SYMBOL npn 360 -368 R0
SYMATTR InstName Q6
SYMBOL diode 264 -112 R270
SYMATTR InstName D3
SYMBOL res 408 128 R0
SYMATTR InstName LOAD
SYMATTR Value {LOAD}
SYMBOL res 392 320 R90
SYMATTR InstName R11
SYMATTR Value 0.1
SYMBOL res 296 48 R90
SYMATTR InstName R9
SYMATTR Value 0.1
SYMBOL res 120 176 R0
SYMATTR InstName R10
SYMATTR Value 8.2k
SYMBOL polcap -104 224 R0
SYMATTR InstName C2
SYMATTR Value 4.7u
SYMBOL res 440 -144 R180
SYMATTR InstName R7
SYMATTR Value 0
SYMBOL npn 664 96 R0
SYMATTR InstName Q7
SYMBOL npn 920 96 M0
SYMATTR InstName Q8
SYMBOL res 776 240 R0
SYMATTR InstName LOAD1
SYMATTR Value 3.3k
SYMBOL res 712 -64 R0
SYMATTR InstName R8
SYMATTR Value 10k
SYMBOL res 840 -64 R0
SYMATTR InstName R12
SYMATTR Value 10k
SYMBOL voltage 792 496 M180
SYMATTR InstName V2
SYMATTR Value 2.4