Version 4
SHEET 1 1184 680
WIRE -160 -128 -256 -128
WIRE -48 -128 -80 -128
WIRE 16 -128 -48 -128
WIRE 128 -128 16 -128
WIRE 256 -128 192 -128
WIRE 352 -128 256 -128
WIRE 528 -128 432 -128
WIRE 560 -128 528 -128
WIRE 608 -128 560 -128
WIRE 736 -128 688 -128
WIRE 256 -96 256 -128
WIRE 528 -96 528 -128
WIRE -160 -32 -192 -32
WIRE -48 -32 -48 -128
WIRE -48 -32 -80 -32
WIRE -256 0 -256 -128
WIRE 736 16 736 -128
WIRE 256 32 256 -16
WIRE 304 32 256 32
WIRE 528 32 528 -16
WIRE 528 32 368 32
WIRE 256 96 256 32
WIRE 528 144 528 32
WIRE 528 144 320 144
WIRE -48 160 -48 -32
WIRE 256 224 256 192
WIRE 304 224 256 224
WIRE 432 224 368 224
WIRE 528 224 528 144
WIRE 528 224 496 224
WIRE -256 352 -256 80
WIRE -192 352 -192 -32
WIRE -192 352 -256 352
WIRE -48 352 -48 224
WIRE -48 352 -192 352
WIRE 256 352 256 224
WIRE 256 352 -48 352
WIRE 736 352 736 96
WIRE 736 352 256 352
WIRE -256 384 -256 352
FLAG -256 384 0
FLAG 560 -128 HDD_TX
FLAG 256 32 RS232C_RxD
FLAG 16 -128 RS232C_RTS
SYMBOL Misc\\signal -256 -16 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V1
SYMATTR Value PULSE(9 -9 8m 10n 10n 8m 16m)
SYMBOL res -64 -144 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName Rzrts
SYMATTR Value 300
SYMBOL cap -64 160 R0
SYMATTR InstName Ccable
SYMATTR Value 330p
SYMBOL diode 128 -112 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D1
SYMATTR Value 1N4148
SYMBOL res 240 -112 R0
SYMATTR InstName R3
SYMATTR Value 2.2k
SYMBOL npn 320 96 M0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL diode 368 16 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName D2
SYMATTR Value 1N4148
SYMBOL zener 368 208 R90
WINDOW 0 0 32 VBottom 0
WINDOW 3 32 32 VTop 0
SYMATTR InstName D3
SYMATTR Value BZX84C6V2L
SYMATTR Description Diode
SYMATTR Type diode
SYMBOL diode 432 240 R270
WINDOW 0 32 32 VTop 0
WINDOW 3 0 32 VBottom 0
SYMATTR InstName D4
SYMATTR Value 1N4148
SYMBOL res 448 -144 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName R2
SYMATTR Value 20k
SYMBOL res 512 -112 R0
SYMATTR InstName R1
SYMATTR Value 2k
SYMBOL Misc\\signal 736 0 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value PULSE(2.5 0 1m 10n 10n 26u 52u)
SYMBOL res 704 -144 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName Rztx
SYMATTR Value 470
SYMBOL res -64 -48 R90
WINDOW 0 0 56 VBottom 0
WINDOW 3 32 56 VTop 0
SYMATTR InstName Rzcts
SYMATTR Value 5k
TEXT 360 0 Left 0 ;Gain more reality transistor CB=NP junction.
TEXT -152 -216 Left 0 ;RS-232C Terminal input/outout protection\nand cable capacitance.
TEXT 264 288 Left 0 ;Gain more reality Vbe break down.
TEXT 760 136 Left 0 ;26us=1/38400s
TEXT 624 -184 Left 0 ;HDD chip output imp. (Temporal value).
TEXT -290 408 Left 0 !.tran 16m