Version 4
SHEET 1 1104 680
WIRE -48 -80 -208 -80
WIRE 192 -80 48 -80
WIRE 336 -80 192 -80
WIRE -48 -16 -48 -80
WIRE 192 -16 192 -80
WIRE 48 16 48 -80
WIRE -208 32 -208 0
WIRE 336 32 336 0
WIRE -48 64 -176 64
WIRE 32 64 -48 64
WIRE 192 64 128 64
WIRE 304 64 192 64
WIRE 496 112 400 112
WIRE -240 128 -416 128
WIRE -176 144 -176 64
WIRE 304 144 304 64
WIRE 496 144 496 112
WIRE -416 160 -416 128
WIRE -240 224 -240 128
WIRE -224 224 -240 224
WIRE 400 224 400 112
WIRE 400 224 352 224
WIRE -416 272 -416 240
WIRE -176 272 -176 240
WIRE 304 272 304 240
WIRE 496 272 496 224
FLAG -208 32 0
FLAG 336 32 0
FLAG -176 272 0
FLAG 304 272 0
FLAG -416 272 0
FLAG 496 272 0
SYMBOL Misc\\2N7002 128 16 R90
SYMATTR InstName U1
SYMBOL res -64 -32 R0
SYMATTR InstName R1
SYMATTR Value 4K7
SYMBOL res 176 -32 R0
SYMATTR InstName R2
SYMATTR Value 4K7
SYMBOL voltage 336 -96 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V1
SYMATTR Value 3.3
SYMBOL voltage -208 -96 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V2
SYMATTR Value 1.8
SYMBOL Misc\\2N7002 -224 144 R0
SYMATTR InstName U2
SYMBOL Misc\\2N7002 352 144 M0
SYMATTR InstName U3
SYMBOL voltage -416 144 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V3
SYMATTR Value PULSE(0 2.5 1000n 10n 10n 2000n 10000n 1)
SYMBOL voltage 496 128 R0
WINDOW 123 0 0 Left 2
WINDOW 39 0 0 Left 2
SYMATTR InstName V4
SYMATTR Value PULSE(0 2.5 10000n 10n 10n 1000n 20000n 1)
TEXT -322 312 Left 2 !.tran 20000n