Version 4 SHEET 1 888 1240 WIRE -608 768 -720 768 WIRE -480 768 -608 768 WIRE -224 768 -480 768 WIRE -96 768 -224 768 WIRE -608 800 -608 768 WIRE -480 800 -480 768 WIRE -224 800 -224 768 WIRE -96 800 -96 768 WIRE -720 816 -720 768 WIRE -608 912 -608 880 WIRE -368 912 -608 912 WIRE -96 912 -96 880 WIRE -96 912 -304 912 WIRE -720 928 -720 896 WIRE -608 944 -608 912 WIRE -96 944 -96 912 WIRE -608 976 -608 944 WIRE -96 976 -96 944 WIRE -512 1024 -544 1024 WIRE -480 1024 -480 880 WIRE -480 1024 -512 1024 WIRE -448 1024 -480 1024 WIRE -368 1024 -304 912 WIRE -368 1024 -384 1024 WIRE -304 1024 -368 912 WIRE -224 1024 -224 880 WIRE -224 1024 -240 1024 WIRE -176 1024 -224 1024 WIRE -160 1024 -176 1024 WIRE -608 1088 -608 1072 WIRE -96 1088 -96 1072 FLAG -96 1088 0 FLAG -608 1088 0 FLAG -720 928 0 FLAG -512 1024 b2 FLAG -176 1024 b1 FLAG -96 944 c1 FLAG -608 944 c2 SYMBOL RES -624 784 R0 SYMATTR InstName R1 SYMATTR Value 4.7k SYMBOL res -112 784 R0 SYMATTR InstName R2 SYMATTR Value 4.7k SYMBOL res -496 784 R0 SYMATTR InstName R3 SYMATTR Value 101K SYMBOL res -240 784 R0 SYMATTR InstName R4 SYMATTR Value 100K SYMBOL cap -384 1008 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C1 SYMATTR Value .01µ SYMBOL cap -240 1008 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C2 SYMATTR Value .01µ SYMBOL VOLTAGE -720 800 R0 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL NPN -160 976 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL npn -544 976 M0 SYMATTR InstName Q2 SYMATTR Value 2N3904 TEXT -744 1152 Left 2 !.tran 0 5m 0 1u startup TEXT -440 1152 Left 2 ;f = 1/(2*ln(2)*R*C) = 700Hz TEXT -744 1184 Left 2 !.options plotwinsize=0