Forums

Colpitts kick-start in LT Spice

Started by Unknown November 11, 2019

The 100-second interval, before the kick-start, does all sorts if fun
stuff, but doesn't seem to want to oscillate. It's super sensitive to
time step and Spice params.

https://www.dropbox.com/s/03mhw5qrkg66v88/CPKS_1.jpg?dl=0

https://www.dropbox.com/s/h6nm3g6rro8ioj7/CPKS_2.jpg?dl=0

https://www.dropbox.com/s/wqnh5de42kpqv38/CPKS_3.jpg?dl=0

https://www.dropbox.com/s/xo6elrlhzvu6mh5/Colpitts_Kick_Start_1.asc?dl=0



Version 4
SHEET 1 1348 680
WIRE 896 -144 672 -144
WIRE 672 -80 672 -144
WIRE 896 -32 896 -144
WIRE 240 0 112 0
WIRE 304 0 240 0
WIRE 464 0 304 0
WIRE 624 0 464 0
WIRE 464 80 464 0
WIRE 112 96 112 0
WIRE 304 112 304 0
WIRE 896 128 896 48
WIRE 896 128 816 128
WIRE 816 160 816 128
WIRE 464 192 464 144
WIRE 576 192 464 192
WIRE 672 192 672 16
WIRE 672 192 576 192
WIRE 464 240 464 192
WIRE 672 256 672 192
WIRE 896 256 896 128
WIRE 112 400 112 176
WIRE 304 400 304 192
WIRE 304 400 112 400
WIRE 464 400 464 304
WIRE 464 400 304 400
WIRE 672 400 672 336
WIRE 896 400 896 336
WIRE 896 400 672 400
WIRE 464 432 464 400
FLAG 240 0 OSC
FLAG 464 432 0
FLAG 816 160 0
FLAG 576 192 SRC
SYMBOL ind 288 96 R0
WINDOW 0 54 39 Left 2
WINDOW 3 60 70 Left 2
SYMATTR InstName L1
SYMATTR Value 1
SYMBOL cap 448 80 R0
WINDOW 0 51 20 Left 2
WINDOW 3 59 54 Left 2
SYMATTR InstName C1
SYMATTR Value 1
SYMBOL current 112 176 R180
WINDOW 0 63 41 Left 2
WINDOW 3 48 -4 Left 2
WINDOW 123 0 0 Left 0
WINDOW 39 0 0 Left 0
SYMATTR InstName I1
SYMATTR Value PULSE(0 10 100 1m 1m 50m)
SYMBOL cap 448 240 R0
WINDOW 0 51 20 Left 2
WINDOW 3 59 54 Left 2
SYMATTR InstName C2
SYMATTR Value 5
SYMBOL nmos 624 -80 R0
WINDOW 0 90 24 Left 2
WINDOW 3 70 58 Left 2
SYMATTR InstName M1
SYMATTR Value 2N7002
SYMBOL res 656 240 R0
WINDOW 0 61 43 Left 2
WINDOW 3 60 78 Left 2
SYMATTR InstName R1
SYMATTR Value 500
SYMBOL voltage 896 -48 R0
WINDOW 0 49 45 Left 2
WINDOW 3 48 80 Left 2
SYMATTR InstName V1
SYMATTR Value 20
SYMBOL voltage 896 240 R0
WINDOW 0 53 37 Left 2
WINDOW 3 57 72 Left 2
SYMATTR InstName V2
SYMATTR Value 20
TEXT -192 376 Left 2 !.tran 0 1000 0 200u
TEXT -192 272 Left 2 ;Colpitts Kick-Start
TEXT -168 312 Left 2 ;JL  Nov 9  2019



-- 

John Larkin         Highland Technology, Inc

lunatic fringe electronics 

On 11.11.19 17:16, jlarkin@highlandsniptechnology.com wrote:
> > > The 100-second interval, before the kick-start, does all sorts if fun > stuff, but doesn't seem to want to oscillate. It's super sensitive to > time step and Spice params. > > https://www.dropbox.com/s/03mhw5qrkg66v88/CPKS_1.jpg?dl=0 > > https://www.dropbox.com/s/h6nm3g6rro8ioj7/CPKS_2.jpg?dl=0 > > https://www.dropbox.com/s/wqnh5de42kpqv38/CPKS_3.jpg?dl=0 > > https://www.dropbox.com/s/xo6elrlhzvu6mh5/Colpitts_Kick_Start_1.asc?dl=0 >
--- original clipped ---
> >
Here is a simplified version with some scaling: Version 4 SHEET 1 1348 680 WIRE 896 -144 672 -144 WIRE 672 -80 672 -144 WIRE 896 -32 896 -144 WIRE 304 0 240 0 WIRE 464 0 304 0 WIRE 624 0 464 0 WIRE 464 80 464 0 WIRE 304 112 304 0 WIRE 896 128 896 48 WIRE 896 128 816 128 WIRE 816 160 816 128 WIRE 464 192 464 144 WIRE 576 192 464 192 WIRE 672 192 672 16 WIRE 672 192 576 192 WIRE 464 240 464 192 WIRE 672 256 672 192 WIRE 896 256 896 128 WIRE 304 400 304 192 WIRE 464 400 464 304 WIRE 464 400 304 400 WIRE 672 400 672 336 WIRE 896 400 896 336 WIRE 896 400 672 400 WIRE 464 432 464 400 FLAG 240 0 OSC FLAG 464 432 0 FLAG 816 160 0 FLAG 576 192 SRC SYMBOL ind 288 96 R0 WINDOW 0 54 39 Left 2 WINDOW 3 60 70 Left 2 SYMATTR InstName L1 SYMATTR Value 1µ SYMBOL cap 448 80 R0 WINDOW 0 51 20 Left 2 WINDOW 3 59 54 Left 2 SYMATTR InstName C1 SYMATTR Value 1µ SYMBOL cap 448 240 R0 WINDOW 0 51 20 Left 2 WINDOW 3 59 54 Left 2 SYMATTR InstName C2 SYMATTR Value 2µ SYMBOL nmos 624 -80 R0 WINDOW 0 90 24 Left 2 WINDOW 3 70 58 Left 2 SYMATTR InstName M1 SYMATTR Value 2N7002 SYMBOL res 656 240 R0 WINDOW 0 61 43 Left 2 WINDOW 3 60 78 Left 2 SYMATTR InstName R1 SYMATTR Value 500 SYMBOL voltage 896 -48 R0 WINDOW 0 49 45 Left 2 WINDOW 3 48 80 Left 2 SYMATTR InstName V1 SYMATTR Value 10 SYMBOL voltage 896 240 R0 WINDOW 0 53 37 Left 2 WINDOW 3 57 72 Left 2 SYMATTR InstName V2 SYMATTR Value 10 TEXT 104 312 Left 2 !.tran 20m TEXT -192 272 Left 2 ;Colpitts Kick-Start TEXT -168 312 Left 2 ;JL Nov 9 2019\nTV Nov 11 2019 TEXT 104 280 Left 2 !.ic V(SRC)=0 ---- -TV
jlarkin@highlandsniptechnology.com wrote:


> The 100-second interval, before the kick-start, does all sorts if fun > stuff, but doesn't seem to want to oscillate. It's super sensitive to > time step and Spice params.
> https://www.dropbox.com/s/03mhw5qrkg66v88/CPKS_1.jpg?dl=0
> https://www.dropbox.com/s/h6nm3g6rro8ioj7/CPKS_2.jpg?dl=0
> https://www.dropbox.com/s/wqnh5de42kpqv38/CPKS_3.jpg?dl=0
> https://www.dropbox.com/s/xo6elrlhzvu6mh5/Colpitts_Kick_Start_1.asc?dl=0
Thanks very much for looking it up. I am running LTspice IV Version 4.23, modified trap. I get completely different results. Not even similar. I suspect there is a problem with the 2N7002 models. In both cases, the 2N7002 is carrying plenty of current and should be able to self-start. It should not need a start pulse. I switched to the 2N7000, using the OrCAD model in the PWRMOS.LIB file in the swcadiii\lib\cmp folder. This is for PSPICE and their work is generally reliable. The 2N7000 version self-starts. Here is the ASC file. Watch the wrap at the model statement. Version 4 SHEET 1 1904 680 WIRE 976 -144 816 -144 WIRE 816 -80 816 -144 WIRE 976 -32 976 -144 WIRE 368 0 320 0 WIRE 640 0 480 0 WIRE 688 0 640 0 WIRE 768 0 688 0 WIRE 368 80 368 0 WIRE 640 80 640 0 WIRE 320 96 320 0 WIRE 480 112 480 0 WIRE 976 128 976 48 WIRE 976 128 896 128 WIRE 896 160 896 128 WIRE 640 192 640 144 WIRE 688 192 640 192 WIRE 816 192 816 16 WIRE 816 192 688 192 WIRE 640 240 640 192 WIRE 816 256 816 192 WIRE 976 256 976 128 WIRE 320 400 320 176 WIRE 480 400 480 192 WIRE 480 400 320 400 WIRE 640 400 640 304 WIRE 640 400 480 400 WIRE 816 400 816 336 WIRE 976 400 976 336 WIRE 976 400 816 400 WIRE 640 432 640 400 FLAG 688 0 OSC FLAG 640 432 0 FLAG 896 160 0 FLAG 688 192 SRC FLAG 368 80 0 SYMBOL ind 464 96 R0 WINDOW 0 54 39 Left 2 WINDOW 3 60 70 Left 2 SYMATTR InstName L1 SYMATTR Value 1 SYMATTR SpiceLine Rser=1m SYMBOL cap 624 80 R0 WINDOW 0 51 20 Left 2 WINDOW 3 59 54 Left 2 SYMATTR InstName C1 SYMATTR Value 1 SYMBOL current 320 176 R180 WINDOW 0 63 41 Left 2 WINDOW 3 -214 220 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName I1 SYMATTR Value PULSE(0 1 100 1m 1m 50m) SYMBOL cap 624 240 R0 WINDOW 0 51 20 Left 2 WINDOW 3 59 54 Left 2 SYMATTR InstName C2 SYMATTR Value 5 SYMBOL nmos 768 -80 R0 WINDOW 0 90 24 Left 2 WINDOW 3 70 58 Left 2 SYMATTR InstName M1 SYMATTR Value 2N7000 SYMBOL res 800 240 R0 WINDOW 0 61 43 Left 2 WINDOW 3 60 78 Left 2 SYMATTR InstName R1 SYMATTR Value 500 SYMBOL voltage 976 -48 R0 WINDOW 0 49 45 Left 2 WINDOW 3 48 80 Left 2 SYMATTR InstName V1 SYMATTR Value 20 SYMBOL voltage 976 240 R0 WINDOW 0 53 37 Left 2 WINDOW 3 57 72 Left 2 SYMATTR InstName V2 SYMATTR Value 20 TEXT 456 -136 Left 2 !.tran 0 2000 0 1m TEXT 456 -168 Left 2 ;'2N7000 Colpitts Self-Start TEXT 328 464 Left 2 !* PWRMOS.LIB \n* NOT SPICE 2G.6 Compatible. FOR USE WITH MICROSIM PSPICE\n.model 2n7000 NMOS(Level=3 Gamma=0 Delta=0 Eta=0 Theta=0 Kappa=0.2 Vmax=0 Xj=0\n+ Tox=2u Uo=600 Phi=.6 Kp= 1.073u W=.12 L=2u Rs=20m Vto=1.73\n+ Rd=.5489 Rds=48MEG Cgso= 73.61p Cgdo=6.487p Cbd=74.46p Mj=.5\n+ Pb=.8 Fc=.5 Rg=546.2 Is=10f N=1 Rb=1m) Here is the PLT file: [Transient Analysis] { Npanes: 3 { traces: 1 {524292,0,"V(src)"} X: ('K',1,0,200,2000) Y[0]: (' ',6,-2.765508,6e-006,-2.765442) Y[1]: ('_',0,1e+308,0,-1e+308) Volts: (' ',0,0,6,-2.765508,6e-006,-2.765442) Log: 0 0 0 GridStyle: 1 }, { traces: 1 {524291,0,"V(osc)"} X: ('K',1,0,200,2000) Y[0]: ('u',0,-1.8e-005,3e-006,1.8e-005) Y[1]: ('_',0,1e+308,0,-1e+308) Volts: ('u',0,0,0,-1.8e-005,3e-006,1.8e-005) Log: 0 0 0 GridStyle: 1 }, { traces: 1 {34603010,0,"Is(M1)"} X: ('K',1,0,200,2000) Y[0]: ('m',4,-0.0344702,2e-007,-0.034468) Y[1]: ('_',0,1e+308,0,-1e+308) Amps: ('m',0,0,5,-0.0344702,2e-007,-0.034468) Log: 0 0 0 GridStyle: 1 } }
Steve Wilson <no@spam.com> wrote:

> jlarkin@highlandsniptechnology.com wrote:
>> The 100-second interval, before the kick-start, does all sorts if fun >> stuff, but doesn't seem to want to oscillate. It's super sensitive to >> time step and Spice params.
>> https://www.dropbox.com/s/03mhw5qrkg66v88/CPKS_1.jpg?dl=0
>> https://www.dropbox.com/s/h6nm3g6rro8ioj7/CPKS_2.jpg?dl=0
>> https://www.dropbox.com/s/wqnh5de42kpqv38/CPKS_3.jpg?dl=0
>> https://www.dropbox.com/s/xo6elrlhzvu6mh5/Colpitts_Kick_Start_1.asc?dl=0
> Thanks very much for looking it up.
> I am running LTspice IV Version 4.23, modified trap.
> I get completely different results. Not even similar. I suspect there is > a problem with the 2N7002 models. In both cases, the 2N7002 is carrying > plenty of current and should be able to self-start. It should not need a > start pulse.
> I switched to the 2N7000, using the OrCAD model in the PWRMOS.LIB file > in the swcadiii\lib\cmp folder. This is for PSPICE and their work is > generally reliable.
> The 2N7000 version self-starts. Here is the ASC file. Watch the wrap at > the model statement.
It's definitely a model problem. The 2N7000 is a T0-92 thu-hole. The 2N7002 is SOT-23 SMD. Electrically they are identical. Just different packages. https://www.mouser.com/datasheet/2/149/2N7002-8405.pdf
Wow, 1 Henry and multiply farad caps, why are you not using real values?

AFAIR you need to have conditions for oscillation covered, specifically the gain setting of C1 and C2

I am running a colpitts in Pspice, and have no startup problems

Cheers

Klaus
Klaus Kragelund <klauskvik@hotmail.com> wrote:

> Wow, 1 Henry and multiply farad caps, why are you not using real values?
> AFAIR you need to have conditions for oscillation covered, specifically > the gain setting of C1 and C2
> I am running a colpitts in Pspice, and have no startup problems
> Cheers
> Klaus
It also works in LTspice if you use the PSPICE model. 1H and 1C are convenient values that also avoid any issues with intelectrode values in the transistor. Recall the 2N7000/2N7002 MOSFET have significant capacitances. I tried making C1=C2. It made little difference to the startup. I often use different capacitor ratios in bipolar Colpitts to get a more sinusoidal output signal. I assume it would also affect the phase noise, but there is no way to measure that in Lspice, and I can't afford the seat cost of the super-expensive sims that do measure phase noise. Anyway, I believe that is one measurement that is best done on the bench.
On Mon, 11 Nov 2019 12:19:12 -0800 (PST), Klaus Kragelund
<klauskvik@hotmail.com> wrote:

>Wow, 1 Henry and multiply farad caps, why are you not using real values?
It's normalized. Why not?
> >AFAIR you need to have conditions for oscillation covered, specifically the gain setting of C1 and C2
It's a perfectly fine oscillator with lots of gain. It just never starts.
> >I am running a colpitts in Pspice, and have no startup problems
It shouldn't start at all. There's no reason why it would prefer to swing positive or negative to get going.
> >Cheers > >Klaus
-- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Monday, November 11, 2019 at 2:31:02 PM UTC-5, Steve Wilson wrote:
> jlarkin@highlandsniptechnology.com wrote: > > > > The 100-second interval, before the kick-start, does all sorts if fun > > stuff, but doesn't seem to want to oscillate. It's super sensitive to > > time step and Spice params. > > > https://www.dropbox.com/s/03mhw5qrkg66v88/CPKS_1.jpg?dl=0 > > > https://www.dropbox.com/s/h6nm3g6rro8ioj7/CPKS_2.jpg?dl=0 > > > https://www.dropbox.com/s/wqnh5de42kpqv38/CPKS_3.jpg?dl=0 > > > https://www.dropbox.com/s/xo6elrlhzvu6mh5/Colpitts_Kick_Start_1.asc?dl=0 > > Thanks very much for looking it up. > > I am running LTspice IV Version 4.23, modified trap. > > I get completely different results. Not even similar. I suspect there is a > problem with the 2N7002 models. In both cases, the 2N7002 is carrying > plenty of current and should be able to self-start. It should not need a > start pulse. > > I switched to the 2N7000, using the OrCAD model in the PWRMOS.LIB file in > the swcadiii\lib\cmp folder. This is for PSPICE and their work is generally > reliable. > > The 2N7000 version self-starts. Here is the ASC file.
This is an attempt to get around the wrap problem in long lines. Version 4 SHEET 1 2804 680 WIRE 976 -144 816 -144 WIRE 816 -80 816 -144 WIRE 976 -32 976 -144 WIRE 368 0 320 0 WIRE 640 0 480 0 WIRE 688 0 640 0 WIRE 768 0 688 0 WIRE 368 80 368 0 WIRE 640 80 640 0 WIRE 320 96 320 0 WIRE 480 112 480 0 WIRE 976 128 976 48 WIRE 976 128 896 128 WIRE 896 160 896 128 WIRE 640 192 640 144 WIRE 688 192 640 192 WIRE 816 192 816 16 WIRE 816 192 688 192 WIRE 640 240 640 192 WIRE 816 256 816 192 WIRE 976 256 976 128 WIRE 320 400 320 176 WIRE 480 400 480 192 WIRE 480 400 320 400 WIRE 640 400 640 304 WIRE 640 400 480 400 WIRE 816 400 816 336 WIRE 976 400 976 336 WIRE 976 400 816 400 WIRE 640 432 640 400 FLAG 688 0 OSC FLAG 640 432 0 FLAG 896 160 0 FLAG 688 192 SRC FLAG 368 80 0 SYMBOL ind 464 96 R0 WINDOW 0 54 39 Left 2 WINDOW 3 60 70 Left 2 SYMATTR InstName L1 SYMATTR Value 1 SYMATTR SpiceLine Rser=1m SYMBOL cap 624 80 R0 WINDOW 0 51 20 Left 2 WINDOW 3 59 54 Left 2 SYMATTR InstName C1 SYMATTR Value 1 SYMBOL current 320 176 R180 WINDOW 0 63 41 Left 2 WINDOW 3 -214 220 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName I1 SYMATTR Value PULSE(0 1 100 1m 1m 50m) SYMBOL cap 624 240 R0 WINDOW 0 51 20 Left 2 WINDOW 3 59 54 Left 2 SYMATTR InstName C2 SYMATTR Value 5 SYMBOL nmos 768 -80 R0 WINDOW 0 90 24 Left 2 WINDOW 3 70 58 Left 2 SYMATTR InstName M1 SYMATTR Value 2N7000 SYMBOL res 800 240 R0 WINDOW 0 61 43 Left 2 WINDOW 3 60 78 Left 2 SYMATTR InstName R1 SYMATTR Value 500 SYMBOL voltage 976 -48 R0 WINDOW 0 49 45 Left 2 WINDOW 3 48 80 Left 2 SYMATTR InstName V1 SYMATTR Value 20 SYMBOL voltage 976 240 R0 WINDOW 0 53 37 Left 2 WINDOW 3 57 72 Left 2 SYMATTR InstName V2 SYMATTR Value 20 TEXT 456 -136 Left 2 !.tran 0 2000 0 1m TEXT 456 -168 Left 2 ;'2N7000 Colpitts Self-Start TEXT 328 464 Left 2 !* PWRMOS.LIB \n* NOT SPICE 2G.6 Compatible. FOR USE WITH MICROSIM PSPICE\n.model 2n7000 NMOS(Level=3 Gamma=0 Delta=0 Eta=0 Theta=0 Kappa=0.2 Vmax=0 Xj=0 Phi=.6 Kp=1.073u W=.12 L=2u Rs=20m Vto=1.73 Rd=.5489 Rds=48MEG Cgso=73.61p Cgdo=6.487p Cbd=74.46p Mj=.5 Pb=.8 Fc=.5 Rg=546.2 Is=10f N=1 Rb=1m)
> Here is the PLT file: > > [Transient Analysis] > { > Npanes: 3 > { > traces: 1 {524292,0,"V(src)"} > X: ('K',1,0,200,2000) > Y[0]: (' ',6,-2.765508,6e-006,-2.765442) > Y[1]: ('_',0,1e+308,0,-1e+308) > Volts: (' ',0,0,6,-2.765508,6e-006,-2.765442) > Log: 0 0 0 > GridStyle: 1 > }, > { > traces: 1 {524291,0,"V(osc)"} > X: ('K',1,0,200,2000) > Y[0]: ('u',0,-1.8e-005,3e-006,1.8e-005) > Y[1]: ('_',0,1e+308,0,-1e+308) > Volts: ('u',0,0,0,-1.8e-005,3e-006,1.8e-005) > Log: 0 0 0 > GridStyle: 1 > }, > { > traces: 1 {34603010,0,"Is(M1)"} > X: ('K',1,0,200,2000) > Y[0]: ('m',4,-0.0344702,2e-007,-0.034468) > Y[1]: ('_',0,1e+308,0,-1e+308) > Amps: ('m',0,0,5,-0.0344702,2e-007,-0.034468) > Log: 0 0 0 > GridStyle: 1 > } > }
John Larkin <jlarkin@highland_atwork_technology.com> wrote:

> On Mon, 11 Nov 2019 12:19:12 -0800 (PST), Klaus Kragelund > <klauskvik@hotmail.com> wrote:
>>Wow, 1 Henry and multiply farad caps, why are you not using real values?
> It's normalized. Why not?
>>AFAIR you need to have conditions for oscillation covered, specifically >>the gain setting of C1 and C2
> It's a perfectly fine oscillator with lots of gain. It just never > starts.
Your model is broken. Use the PSPICE model. It self-starts.
>>I am running a colpitts in Pspice, and have no startup problems
> It shouldn't start at all.
Sure it should. It meets Barkhausen. Here is the first 20 seconds showing the self-start. Version 4 SHEET 1 2804 680 WIRE 976 -144 816 -144 WIRE 816 -80 816 -144 WIRE 976 -32 976 -144 WIRE 368 0 320 0 WIRE 640 0 480 0 WIRE 688 0 640 0 WIRE 768 0 688 0 WIRE 368 80 368 0 WIRE 640 80 640 0 WIRE 320 96 320 0 WIRE 480 112 480 0 WIRE 976 128 976 48 WIRE 976 128 896 128 WIRE 896 160 896 128 WIRE 640 192 640 144 WIRE 688 192 640 192 WIRE 816 192 816 16 WIRE 816 192 688 192 WIRE 640 240 640 192 WIRE 816 256 816 192 WIRE 976 256 976 128 WIRE 320 400 320 176 WIRE 480 400 480 192 WIRE 480 400 320 400 WIRE 640 400 640 304 WIRE 640 400 480 400 WIRE 816 400 816 336 WIRE 976 400 976 336 WIRE 976 400 816 400 WIRE 640 432 640 400 FLAG 688 0 OSC FLAG 640 432 0 FLAG 896 160 0 FLAG 688 192 SRC FLAG 368 80 0 SYMBOL ind 464 96 R0 WINDOW 0 54 39 Left 2 WINDOW 3 60 70 Left 2 SYMATTR InstName L1 SYMATTR Value 1 SYMATTR SpiceLine Rser=1m SYMBOL cap 624 80 R0 WINDOW 0 51 20 Left 2 WINDOW 3 59 54 Left 2 SYMATTR InstName C1 SYMATTR Value 1 SYMBOL current 320 176 R180 WINDOW 0 63 41 Left 2 WINDOW 3 -214 220 Left 2 WINDOW 123 0 0 Left 2 WINDOW 39 0 0 Left 2 SYMATTR InstName I1 SYMATTR Value PULSE(0 1 100 1m 1m 50m) SYMBOL cap 624 240 R0 WINDOW 0 51 20 Left 2 WINDOW 3 59 54 Left 2 SYMATTR InstName C2 SYMATTR Value 5 SYMBOL nmos 768 -80 R0 WINDOW 0 90 24 Left 2 WINDOW 3 70 58 Left 2 SYMATTR InstName M1 SYMATTR Value 2N7000 SYMBOL res 800 240 R0 WINDOW 0 61 43 Left 2 WINDOW 3 60 78 Left 2 SYMATTR InstName R1 SYMATTR Value 500 SYMBOL voltage 976 -48 R0 WINDOW 0 49 45 Left 2 WINDOW 3 48 80 Left 2 SYMATTR InstName V1 SYMATTR Value 20 SYMBOL voltage 976 240 R0 WINDOW 0 53 37 Left 2 WINDOW 3 57 72 Left 2 SYMATTR InstName V2 SYMATTR Value 20 TEXT 456 -136 Left 2 !.tran 0 20 0 1m TEXT 456 -168 Left 2 ;'2N7000 Colpitts Self-Start TEXT 328 464 Left 2 !* PWRMOS.LIB \n* NOT SPICE 2G.6 Compatible. FOR USE WITH MICROSIM PSPICE\n.model 2n7000 NMOS(Level=3 Gamma=0 Delta=0 Eta=0 Theta=0 Kappa=0.2 Vmax=0 Xj=0 Phi=.6 Kp=1.073u W=.12 L=2u Rs=20m Vto=1.73 Rd=.5489 Rds=48MEG Cgso=73.61p Cgdo=6.487p Cbd=74.46p Mj=.5 Pb=.8 Fc=.5 Rg= 546.2 Is=10f N=1 Rb=1m) Here is the PLT file [Transient Analysis] { Npanes: 1 { traces: 1 {524290,0,"V(osc)"} X: (' ',0,0,2,20) Y[0]: ('p',0,-1e-009,2e-010,1e-009) Y[1]: ('_',0,1e+308,0,-1e+308) Volts: ('p',0,0,1,-1e-009,2e-010,1e-009) Log: 0 0 0 GridStyle: 1 } }
On Tue, 12 Nov 2019 01:36:13 -0000 (UTC), Steve Wilson <no@spam.com>
wrote:

>John Larkin <jlarkin@highland_atwork_technology.com> wrote: > >> On Mon, 11 Nov 2019 12:19:12 -0800 (PST), Klaus Kragelund >> <klauskvik@hotmail.com> wrote: > >>>Wow, 1 Henry and multiply farad caps, why are you not using real values? > >> It's normalized. Why not? > >>>AFAIR you need to have conditions for oscillation covered, specifically >>>the gain setting of C1 and C2 > >> It's a perfectly fine oscillator with lots of gain. It just never >> starts. > >Your model is broken. Use the PSPICE model. It self-starts.
If any oscillator of this kind starts in simulation, something is indeed broken. 0 multiplied exponentially is still 0. -- John Larkin Highland Technology, Inc lunatic fringe electronics