Version 4 SHEET 1 1388 1092 WIRE 432 -288 432 -304 WIRE -400 -240 -400 -256 WIRE -880 -224 -928 -224 WIRE -752 -224 -816 -224 WIRE 336 -192 320 -192 WIRE 432 -192 432 -224 WIRE 432 -192 416 -192 WIRE 480 -192 432 -192 WIRE 576 -192 560 -192 WIRE 624 -192 576 -192 WIRE 720 -192 720 -240 WIRE 720 -192 704 -192 WIRE 576 -176 576 -192 WIRE 720 -160 720 -192 WIRE -976 -144 -1200 -144 WIRE -880 -144 -976 -144 WIRE -752 -144 -752 -224 WIRE -752 -144 -816 -144 WIRE -720 -144 -752 -144 WIRE -400 -144 -400 -160 WIRE -400 -144 -544 -144 WIRE -288 -144 -400 -144 WIRE -80 -144 -288 -144 WIRE -1200 -128 -1200 -144 WIRE -400 -128 -400 -144 WIRE -80 -128 -80 -144 WIRE 208 -112 208 -144 WIRE 320 -112 304 -112 WIRE 432 -112 432 -192 WIRE 432 -112 400 -112 WIRE -544 -96 -544 -144 WIRE -752 -80 -928 -80 WIRE 496 -80 496 -96 WIRE 576 -80 576 -96 WIRE -752 -64 -752 -80 WIRE -288 -64 -288 -144 WIRE 432 -64 432 -112 WIRE 464 -64 432 -64 WIRE -400 -48 -400 -64 WIRE 720 -48 720 -80 WIRE 720 -48 528 -48 WIRE 752 -48 720 -48 WIRE 784 -48 752 -48 WIRE -1200 -32 -1200 -48 WIRE 464 -32 432 -32 WIRE -176 -16 -192 -16 WIRE -80 -16 -80 -48 WIRE -80 -16 -96 -16 WIRE -48 -16 -80 -16 WIRE 48 -16 16 -16 WIRE 112 -16 48 -16 WIRE 208 -16 208 -48 WIRE 208 -16 176 -16 WIRE 304 -16 304 -112 WIRE 304 -16 208 -16 WIRE 320 -16 304 -16 WIRE 416 -16 400 -16 WIRE 432 -16 432 -32 WIRE 432 -16 416 -16 WIRE 208 0 208 -16 WIRE 416 0 416 -16 WIRE 496 0 496 -16 WIRE -80 16 -80 -16 WIRE 48 16 48 -16 WIRE -704 64 -816 64 WIRE -544 64 -544 -16 WIRE -544 64 -656 64 WIRE -496 64 -544 64 WIRE -400 64 -432 64 WIRE -384 64 -400 64 WIRE -288 64 -288 16 WIRE -288 64 -304 64 WIRE -272 64 -288 64 WIRE -192 64 -192 -16 WIRE -192 64 -208 64 WIRE -144 64 -192 64 WIRE -656 80 -656 64 WIRE -192 80 -192 64 WIRE 416 80 416 64 WIRE -704 96 -704 64 WIRE -544 96 -544 64 WIRE -288 96 -288 64 WIRE 48 96 48 80 WIRE 208 112 208 80 WIRE 304 112 304 -16 WIRE 544 112 304 112 WIRE 720 112 720 -48 WIRE 720 112 624 112 WIRE -80 128 -80 112 WIRE -400 144 -400 64 WIRE -352 144 -400 144 WIRE -400 160 -400 144 WIRE -1424 176 -1472 176 WIRE -1328 176 -1424 176 WIRE -1216 176 -1264 176 WIRE -1120 176 -1216 176 WIRE -816 176 -816 64 WIRE -816 176 -1120 176 WIRE -800 176 -816 176 WIRE -704 176 -704 144 WIRE -704 176 -720 176 WIRE -656 176 -656 160 WIRE -544 176 -544 160 WIRE -544 176 -656 176 WIRE -192 176 -192 160 WIRE -1120 192 -1120 176 WIRE -704 192 -704 176 WIRE -544 192 -544 176 WIRE -1216 208 -1216 176 WIRE -816 208 -816 176 WIRE -1424 240 -1424 176 WIRE -288 240 -288 192 WIRE -400 256 -400 240 WIRE -1120 288 -1120 272 WIRE -1040 288 -1120 288 WIRE -944 288 -1040 288 WIRE -704 288 -704 256 WIRE -704 288 -912 288 WIRE -1216 304 -1216 288 WIRE -1040 304 -1040 288 WIRE -1424 336 -1424 320 WIRE -816 336 -816 272 WIRE -800 336 -816 336 WIRE -704 336 -704 288 WIRE -704 336 -720 336 WIRE -1120 368 -1120 288 WIRE -704 368 -704 336 WIRE -1040 416 -1040 384 WIRE -1040 416 -1056 416 WIRE -1024 416 -1040 416 WIRE -944 416 -912 288 WIRE -944 416 -960 416 WIRE -912 416 -944 288 WIRE -896 416 -912 416 WIRE -816 416 -816 336 WIRE -816 416 -832 416 WIRE -768 416 -816 416 WIRE -1120 480 -1120 464 WIRE -704 480 -704 464 FLAG -1200 -32 0 FLAG -1424 336 0 FLAG -720 -144 +V FLAG -928 -80 DB9_Pin5 FLAG -976 -144 DB9_Pin4 FLAG -1472 176 DB9_Pin3 FLAG -1424 176 Tx FLAG -752 -64 0 FLAG -544 192 0 FLAG -288 240 0 FLAG -400 256 0 FLAG -400 -256 +V FLAG -400 -48 0 FLAG -80 128 0 FLAG -192 176 0 FLAG 496 0 0 FLAG 720 -240 +V FLAG 320 -192 0 FLAG 496 -96 +V FLAG 48 96 0 FLAG 208 112 0 FLAG 208 -144 0 FLAG 432 -304 0 FLAG 576 -80 0 FLAG 416 80 0 FLAG 784 -48 BD9_Pin2 FLAG 752 -48 Rx FLAG -1120 480 0 FLAG -704 480 0 FLAG -1216 304 0 FLAG -928 -224 DB9_Pin7 SYMBOL voltage -1200 -144 R0 WINDOW 3 42 60 Left 0 WINDOW 123 0 0 Left 0 WINDOW 39 28 91 Left 0 SYMATTR Value 5.6 SYMATTR SpiceLine Rser=50 SYMATTR InstName V1 SYMBOL res -816 192 R270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R4 SYMATTR Value 2K SYMBOL npn -768 368 R0 SYMATTR InstName Q2 SYMATTR Value 2N3904 SYMBOL npn -1056 368 M0 WINDOW 0 46 -6 Right 0 WINDOW 3 36 102 Right 0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL res -1136 176 R0 SYMATTR InstName R2 SYMATTR Value 24.9K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL cap -832 400 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C4 SYMATTR Value 100p SYMBOL cap -960 400 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C2 SYMATTR Value 100p SYMBOL res -1056 400 M180 WINDOW 0 36 76 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName R1 SYMATTR Value 90.9K SYMBOL res -704 320 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R5 SYMATTR Value 162K SYMBOL voltage -1424 224 R0 WINDOW 123 0 0 Left 0 WINDOW 39 38 63 Left 0 WINDOW 3 32 139 Top 0 SYMATTR SpiceLine Rser=50 SYMATTR Value PULSE(-5.6 5.6 0 .1u .1u {1/baud} {2/baud}) SYMATTR InstName V2 SYMBOL diode -1328 160 M90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName D3 SYMATTR Value 1N4148 SYMBOL cap -768 -144 R0 WINDOW 0 24 16 Left 0 WINDOW 3 24 53 Left 0 SYMATTR InstName C1 SYMATTR Value 1µ SYMBOL diode -720 192 R0 SYMATTR InstName D4 SYMATTR Value TX SYMBOL diode -880 -160 M90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName D2 SYMATTR Value 1N4148 SYMBOL diode -560 160 M180 WINDOW 0 24 72 Left 0 WINDOW 3 24 0 Left 0 SYMATTR InstName D8 SYMATTR Value BPV23NFL SYMBOL g2 -656 176 M180 WINDOW 0 26 92 Left 0 WINDOW 3 26 24 Left 0 SYMATTR InstName G1 SYMATTR Value {Y} SYMBOL res -560 0 M180 WINDOW 0 36 76 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName R22 SYMATTR Value 4.99K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL npn -352 96 R0 SYMATTR InstName Q4 SYMATTR Value 2N3904 SYMBOL res -304 32 M180 WINDOW 0 36 76 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName R19 SYMATTR Value 10K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res -400 48 M90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R20 SYMATTR Value 249K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res -416 256 M180 WINDOW 0 36 76 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName R21 SYMATTR Value 121K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL cap -432 80 M270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName C11 SYMATTR Value 500p SYMBOL cap -416 -128 R0 WINDOW 0 24 16 Left 0 WINDOW 3 24 53 Left 0 SYMATTR InstName C9 SYMATTR Value 1µ SYMBOL res -416 -144 M180 WINDOW 0 36 76 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName R15 SYMATTR Value 249 SYMBOL npn -144 16 R0 SYMATTR InstName Q3 SYMATTR Value 2N3904 SYMBOL res -96 -32 M180 WINDOW 0 36 76 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName R16 SYMATTR Value 10K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res -192 -32 M90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R17 SYMATTR Value 499K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res -208 176 M180 WINDOW 0 31 76 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName R18 SYMATTR Value 221K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL cap -208 80 M270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName C10 SYMATTR Value 300p SYMBOL res 576 -176 M270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R8 SYMATTR Value 1.1Meg SYMBOL res 432 -176 M270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R10 SYMATTR Value 1.1Meg SYMBOL res 192 96 M180 WINDOW 0 36 76 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName R14 SYMATTR Value 24.9K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL cap 192 -48 M180 WINDOW 0 24 64 Left 0 WINDOW 3 24 8 Left 0 SYMATTR InstName C7 SYMATTR Value 330p SYMBOL cap 416 -288 R0 SYMATTR InstName C5 SYMATTR Value 100p SYMBOL res 560 -192 R0 SYMATTR InstName R9 SYMATTR Value 24.9K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 720 -176 M270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R7 SYMATTR Value 249K SYMBOL cap 400 0 R0 SYMATTR InstName C6 SYMATTR Value 30p SYMBOL cap 16 0 M270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName C8 SYMATTR Value 300p SYMBOL diode 112 0 R270 WINDOW 0 32 32 VTop 0 WINDOW 3 0 32 VBottom 0 SYMATTR InstName D5 SYMATTR Value 1N4148 SYMBOL diode 32 80 M180 WINDOW 0 24 72 Left 0 WINDOW 3 24 0 Left 0 SYMATTR InstName D6 SYMATTR Value 1N4148 SYMBOL res 704 -176 R0 SYMATTR InstName R6 SYMATTR Value 4.99K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 304 -32 M90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R13 SYMATTR Value 162K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL Comparators\\LT1018 496 -48 R0 WINDOW 0 21 -23 Left 0 WINDOW 3 23 48 Left 0 SYMATTR InstName U1 SYMBOL res 304 -128 M90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R12 SYMATTR Value 249K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL res 640 128 M270 WINDOW 0 32 56 VTop 0 WINDOW 3 0 56 VBottom 0 SYMATTR InstName R11 SYMATTR Value 1.1Meg SYMBOL res -1232 304 M180 WINDOW 0 36 76 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName R3 SYMATTR Value 10K SYMATTR SpiceLine tol=1 pwr=0.1 SYMBOL diode -880 -240 M90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName D1 SYMATTR Value 1N4148 SYMBOL cap -832 272 M180 WINDOW 0 26 49 Left 0 WINDOW 3 24 8 Left 0 SYMATTR InstName C3 SYMATTR Value 10p TEXT -144 216 Left 0 !.tran 1m TEXT -144 240 Left 0 !.param Y=100n TEXT -144 264 Left 0 ;.step param Y 100n 200n 50n TEXT -1520 -168 Left 0 ;Serial DB9 Pinout:\n 1 Data Carrier Detect\n 2 Received Data\n 3 Transmitted Data\n 4 Data Terminal Ready\n 5 Signal Ground\n 6 Data Set Ready\n 7 Request to Send\n 8 Clear to send\n 9 Ring Indicator TEXT -584 320 Left 0 !.param baud=9600\n.model TX D(Cjo=18p)\n.model BPV23NFL D(Is=1n Rs=900 Cjo=48p) TEXT -672 48 Bottom 0 ;"Loopback\nTest"