Version 4
SHEET 1 1100 680
WIRE 592 -192 -144 -192
WIRE -144 -80 -144 -192
WIRE -144 -80 -288 -80
WIRE -288 0 -288 -80
WIRE -256 0 -288 0
WIRE -144 16 -144 -80
WIRE -144 16 -192 16
WIRE 368 16 368 -80
WIRE 368 16 256 16
WIRE -256 32 -368 32
WIRE 480 80 256 80
WIRE 368 144 368 16
WIRE 368 144 256 144
WIRE -288 208 -496 208
WIRE -32 208 -288 208
WIRE 368 208 256 208
WIRE -32 272 -368 272
WIRE 480 272 256 272
WIRE -32 336 -144 336
WIRE 368 336 368 208
WIRE 368 336 256 336
WIRE -32 400 -96 400
WIRE 592 400 592 -192
WIRE 592 400 256 400
WIRE -288 416 -288 208
WIRE -144 416 -288 416
WIRE 368 448 368 336
FLAG -224 48 0
FLAG 368 448 0
FLAG -96 464 0
FLAG -368 352 0
FLAG -496 272 0
FLAG 448 -112 +9VCC
FLAG -448 -80 +5VCC
FLAG -192 -32 +9VCC
FLAG 112 208 SG3525
FLAG -48 464 1µ
FLAG -544 256 1NF
FLAG -320 336 3.5K
FLAG -96 384 100
FLAG -240 96 LM741
FLAG -368 112 0
FLAG -432 80 10KPOT
SYMBOL Opamps\\LT1001A -224 -48 R0
WINDOW 0 332 48 Left 2
WINDOW 3 198 83 Left 2
SYMATTR InstName U1
SYMBOL res -384 -64 R0
WINDOW 0 552 58 Left 2
WINDOW 3 516 16 Left 2
SYMATTR InstName R1
SYMBOL Misc\\DIP16 112 48 R0
SYMATTR InstName U2
SYMBOL res -384 256 R0
WINDOW 0 -56 49 Left 2
WINDOW 3 -73 48 Left 2
SYMATTR InstName R3
SYMBOL cap -512 208 R0
WINDOW 0 51 29 Left 2
WINDOW 3 248 -259 Left 2
SYMATTR InstName C1
SYMBOL res -160 320 R0
WINDOW 0 -84 51 Left 2
WINDOW 3 -100 51 Left 2
SYMATTR InstName R4
SYMBOL cap -112 400 R0
WINDOW 0 -136 50 Left 2
WINDOW 3 -167 -451 Left 2
SYMATTR InstName C2
SYMBOL voltage -368 -144 R0
SYMATTR InstName V1
SYMBOL voltage 368 -176 R0
SYMATTR InstName V2
SYMBOL Misc\\xvaristor -384 16 R0
WINDOW 0 69 65 Left 2
WINDOW 3 -96 17 Left 2
SYMATTR InstName U3