Version 4
SHEET 1 1652 680
WIRE 80 80 16 80
WIRE 400 80 336 80
WIRE 16 112 16 80
WIRE 336 112 336 80
WIRE 16 224 16 192
WIRE 336 224 336 192
WIRE 64 320 0 320
WIRE 400 320 336 320
WIRE 0 352 0 320
WIRE 336 352 336 320
WIRE 0 464 0 432
WIRE 336 464 336 432
FLAG 336 224 0
FLAG 16 224 0
FLAG 400 80 rand2
IOPIN 400 80 Out
FLAG 80 80 rand1
IOPIN 80 80 Out
FLAG 0 464 0
FLAG 64 320 rand3
IOPIN 64 320 Out
FLAG 336 464 0
FLAG 400 320 rand4
IOPIN 400 320 Out
SYMBOL bv 336 96 R0
SYMATTR InstName B1
SYMATTR Value V=rand(time*1K+10k)
SYMBOL bv 16 96 R0
SYMATTR InstName B3
SYMATTR Value V=rand(time*1K)
SYMBOL bv 0 336 R0
SYMATTR InstName B2
SYMATTR Value V=rand(time*1K+20k)
SYMBOL bv 336 336 R0
SYMATTR InstName B4
SYMATTR Value V=rand(time*1K+30k)
TEXT -8 -160 Left 2 !.tran 0 30m\n.options maxstep=10u
TEXT -8 32 Left 2 ;rectangular  0 to +1.0
TEXT -8 -72 Left 2 !.options plotwinsize=0
TEXT 280 -72 Left 2 ;Outpput data compression off
TEXT 280 -160 Left 2 ;Plot step time <0.01*1/FREQUENCY. \nFREQUENCY is 1KHz in this example
TEXT -24 544 Left 2 ;Option for a random start of each simulation:\nControl Panel -> Hacks \nUse the clock to reseed the MC generator [x]