Electronic circuit simulator

----- Original Message ----- From: "Bill Bowden" Newsgroups: sci.electronics.basics Sent: Tuesday, December 28, 2010 3:57 AM Subject: Re: Electronic circuit simulator

Yes, there's a lot to learn. I have no idea what I'm doing. I just used the existing simulation command from one of the examples, for .tran 20m startup to look at a wien bridge oscillator. I managed to get the thing to start running after some delay and then stop. I've never seen an oscillator that starts up and puts out a few good cycles and then stops. Maybe some error in the simulation command.

-Bill

Hello Bill,

Sometimes it's necessary to force a maximum time step.

.tran 0 10m 0 1u startup

Oscillation of a Wien-oscillator requires a gain of 3 or more. Has your circuit enough gain?

Best regards, Helmut

On Dec 28, 6:37=A0am, "Helmut Sennewald" wrote:

I think I got it working with a little more stop time ( .tran 30m startup). It takes about 20ms to startup. Yes, the gain is critical, too much gain clips the waveform, and not enough stops the circuit. I had to tweek R11 to 644 ohms to get it close. The problem is the simulation doesn't respond to the AGC feedback from the lamp simulated by R7 (57 ohms). But I'm happy I got the thing to work. Works ok on the bench as well with the AGC working.

Here's the circuit:

Version 4 SHEET 1 888 1364 WIRE -800 704 -864 704 WIRE -640 704 -720 704 WIRE -544 704 -640 704 WIRE -384 704 -544 704 WIRE -224 704 -384 704 WIRE 80 704 -224 704 WIRE -224 736 -224 704 WIRE 80 736 80 704 WIRE -864 752 -864 704 WIRE -544 752 -544 704 WIRE -640 800 -640 704 WIRE -864 816 -864 752 WIRE 80 848 80 816 WIRE 80 848 -48 848 WIRE -864 864 -864 832 WIRE 80 864 80 848 WIRE 112 864 80 864 WIRE 240 864 176 864 WIRE -224 896 -224 816 WIRE -160 896 -224 896 WIRE -384 928 -384 704 WIRE -224 928 -224 896 WIRE 80 928 80 864 WIRE -784 976 -864 976 WIRE -704 976 -784 976 WIRE -656 976 -704 976 WIRE -544 976 -544 832 WIRE -544 976 -592 976 WIRE -448 976 -544 976 WIRE -288 976 -320 976 WIRE -160 976 -160 896 WIRE -144 976 -160 976 WIRE -48 976 -48 928 WIRE -48 976 -80 976 WIRE 16 976 -48 976 WIRE 80 1040 80 1024 WIRE 96 1040 80 1040 WIRE -384 1056 -384 1024 WIRE -320 1056 -320 976 WIRE -320 1056 -384 1056 WIRE -784 1088 -784 1040 WIRE -704 1088 -704 1056 WIRE -544 1088 -544 976 WIRE -384 1088 -384 1056 WIRE -224 1088 -224 1024 WIRE 80 1088 80 1040 WIRE 160 1088 160 1040 WIRE -544 1200 -544 1168 WIRE -384 1200 -384 1168 WIRE -224 1200 -224 1168 WIRE 80 1200 80 1168 WIRE 160 1200 160 1168 WIRE -864 1248 -864 976 WIRE 240 1248 240 944 WIRE 240 1248 -864 1248 FLAG -864 864 0 FLAG 80 1200 0 FLAG -784 1088 0 FLAG -704 1088 0 FLAG -224 1200 0 FLAG -384 1200 0 FLAG -544 1200 0 FLAG 160 1200 0 FLAG -640 864 0 SYMBOL res 64 720 R0 SYMATTR InstName R2 SYMATTR Value 100 SYMBOL res -64 832 R0 WINDOW 0 46 40 Left 0 WINDOW 3 45 72 Left 0 SYMATTR InstName R4 SYMATTR Value 16k SYMBOL VOLTAGE -864 736 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 WINDOW 0 50 56 Left 0 WINDOW 3 103 54 Left 0 SYMATTR InstName V1 SYMATTR Value 12 SYMBOL NPN 16 928 R0 WINDOW 0 50 356 Left 0 WINDOW 3 24 393 Left 0 SYMATTR InstName Q1 SYMATTR Value 2N2219A SYMBOL NPN -448 928 R0 WINDOW 0 53 359 Left 0 WINDOW 3 30 394 Left 0 SYMATTR InstName Q2 SYMATTR Value 2N3904 SYMBOL res 224 848 R0 WINDOW 0 42 32 Left 0 WINDOW 3 41 64 Left 0 SYMATTR InstName R3 SYMATTR Value 10k SYMBOL res -560 736 R0 WINDOW 0 53 40 Left 0 SYMATTR InstName R6 SYMATTR Value 330k SYMATTR SpiceLine tol=3D1 pwr=3D0.1 SYMBOL res 64 1072 R0 WINDOW 0 -39 74 Left 0 WINDOW 3 -39 100 Left 0 SYMATTR InstName R8 SYMATTR Value 51 SYMBOL cap -800 976 R0 WINDOW 0 -32 54 Left 0 WINDOW 3 -43 82 Left 0 SYMATTR InstName C3 SYMATTR Value 750pf SYMBOL cap -592 960 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C2 SYMATTR Value .1=B5 SYMBOL res -720 960 R0 WINDOW 0 -6 182 Left 0 WINDOW 3 -10 210 Left 0 SYMATTR InstName R10 SYMATTR Value 10k SYMBOL RES -240 720 R0 WINDOW 0 49 39 Left 0 WINDOW 3 47 71 Left 0 SYMATTR InstName R11 SYMATTR Value 644 SYMBOL res -240 1072 R0 WINDOW 0 47 38 Left 0 WINDOW 3 44 69 Left 0 SYMATTR InstName R12 SYMATTR Value 510 SYMBOL NPN -288 928 R0 WINDOW 0 51 359 Left 0 WINDOW 3 31 393 Left 0 SYMATTR InstName Q3 SYMATTR Value 2N3904 SYMBOL res -400 1072 R0 WINDOW 0 41 40 Left 0 SYMATTR InstName R1 SYMATTR Value 20k SYMBOL res -560 1072 R0 WINDOW 0 50 40 Left 0 WINDOW 3 50 72 Left 0 SYMATTR InstName R5 SYMATTR Value 330k SYMBOL cap 160 1024 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 -26 -33 VTop 0 SYMATTR InstName C5 SYMATTR Value 1000=B5 SYMBOL res 144 1072 R0 WINDOW 0 47 37 Left 0 WINDOW 3 46 71 Left 0 SYMATTR InstName R7 SYMATTR Value 57 SYMBOL cap 176 848 R90 WINDOW 0 0 32 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C1 SYMATTR Value 750pf SYMBOL cap -80 960 R90 WINDOW 0 60 69 VBottom 0 WINDOW 3 32 32 VTop 0 SYMATTR InstName C6 SYMATTR Value 1=B5 SYMBOL cap -656 800 R0 WINDOW 0 -49 33 Left 0 WINDOW 3 -75 65 Left 0 SYMATTR InstName C4 SYMATTR Value 100=B5 SYMBOL res -704 688 R90 WINDOW 0 0 56 VBottom 0 WINDOW 3 32 56 VTop 0 SYMATTR InstName R9 SYMATTR Value 51 TEXT -960 1344 Left 0 !.tran 30m startup