I'm trying to simulate an astable multivibrator with ngspice, but the graphic i get is odd. I simulated the same circuit with qucs and ยก didn't have any problem. I'm trying to figure out where the problem is.
This is the netlist: ********************************************************* *vvvvvvvv Included SPICE model from uA741.lib vvvvvvvv * Model for uA741 Op Amp (from EVAL library in PSpice) * connections: non-inverting input * | inverting input * | | positive power supply * | | | negative power supply * | | | | output * | | | | | * .subckt uA741 1 2 3 4 5 * c1 11 12 8.661E-12 c2 6 7 30.00E-12 dc 5 53 dy de 54 5 dy dlp 90 91 dx dln 92 90 dx dp 4 3 dx egnd 99 0 poly(2),(3,0),(4,0) 0 .5 .5 fb 7 99 poly(5) vb vc ve vlp vln 0 10.61E6 -1E3 1E3 10E6 -10E6 ga 6 0 11 12 188.5E-6 gcm 0 6 10 99 5.961E-9 iee 10 4 dc 15.16E-6 hlim 90 0 vlim 1K q1 11 2 13 qx q2 12 1 14 qx r2 6 9 100.0E3 rc1 3 11 5.305E3 rc2 3 12 5.305E3 re1 13 10 1.836E3 re2 14 10 1.836E3 ree 10 99 13.19E6 ro1 8 5 50 ro2 7 99 100 rp 3 4 18.16E3 vb 9 0 dc 0 vc 3 53 dc 1 ve 54 4 dc 1 vlim 7 8 dc 0 vlp 91 0 dc 40 vln 0 92 dc 40 .model dx D(Is=800.0E-18 Rs=1) .model dy D(Is=800.00E-18 Rs=1m Cjo=10p) .model qx NPN(Is=800.0E-18 Bf=93.75) .ends *^^^^^^^^ End of included SPICE model from uA741.lib ^^^^^^^^ * *============== Begin SPICE netlist of main design ============ V2 Vcc 0 DC 15V R3 3 1 50k R2 0 1 2.2k R1 2 3 50k C1 0 2 1u XU1 1 2 Vcc -Vcc 3 uA741 .control tran 0.1m 30m plot v(3) .endc .end The graphic i get is like this: http://img152.imageshack.us/my.php?image=ngspice.jpg The voltage drop below 400V what's the problem?!! Thanks in advance -- View this message in context: http://www.nabble.com/problem-to-simulate-an-astable-multivibrator-with-uA741-opamp-tp23057811p23057811.html Sent from the gEDA - User mailing list archive at Nabble.com. _______________________________________________ geda-user mailing list geda-user@moria.seul.org http://www.seul.org/cgi-bin/mailman/listinfo/geda-user