Version 4
SHEET 1 880 680
WIRE 304 -128 -352 -128
WIRE 480 -128 304 -128
WIRE 304 -64 304 -128
WIRE 480 -64 480 -128
WIRE 480 64 480 16
WIRE 592 64 480 64
WIRE 480 80 480 64
WIRE 304 96 304 16
WIRE 304 96 240 96
WIRE 304 128 304 96
WIRE 416 128 304 128
WIRE 304 192 304 128
WIRE 64 240 64 208
WIRE 64 240 -96 240
WIRE 240 240 64 240
WIRE -352 304 -352 -128
WIRE -96 320 -96 240
WIRE 304 320 304 288
WIRE 304 320 224 320
WIRE 480 320 480 176
WIRE 480 320 304 320
WIRE 304 368 304 320
WIRE -352 512 -352 384
WIRE -96 512 -96 400
WIRE 304 512 304 448
FLAG 304 512 0
FLAG -96 512 0
FLAG -352 512 0
FLAG 592 64 VOUT
FLAG 64 208 VIN
FLAG 240 96 V1
FLAG 224 320 V2
SYMBOL voltage -352 288 R0
WINDOW 123 0 0 Left 0
WINDOW 39 24 124 Left 2
SYMATTR SpiceLine Rser=0
SYMATTR InstName V1
SYMATTR Value 5
SYMBOL res 288 -80 R0
SYMATTR InstName R1
SYMATTR Value 100k
SYMBOL res 288 352 R0
SYMATTR InstName R2
SYMATTR Value 3.3k
SYMBOL npn 240 192 R0
SYMATTR InstName Q1
SYMATTR Value 2N3904
SYMBOL npn 416 80 R0
SYMATTR InstName Q2
SYMATTR Value 2N3904
SYMBOL voltage -96 304 R0
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName V2
SYMATTR Value PULSE(0 5 0 0.5 0.5 0 1)
SYMBOL res 464 -80 R0
SYMATTR InstName R3
SYMATTR Value 10k
TEXT -48 472 Left 2 !.tran 0 2 0
TEXT -152 616 Left 2 ;Refer to the following URL:\nhttps://synapse.kyoto/glossary/schmitt-trigger/page001.html