Using Spice to verify a circuit works

So, a self-starting oscillator, you don't model that? Lame, like your other excuses and lies.

Believe the models, or improve them, but don't spin feeble devil-theories about 'em.

Reply to
whit3rd
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Of course I model oscillators. I did a triggered 40 Mhz clock oscillator sim today. Well, I guess that if it's triggered it's not self-starting.

Lies? I design electronic things that work. People like them. People buy them.

I just introduced my new Pockels Cell driver.

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It can actually make a 1400 volt, 10 ns pulse. We were scared to push it any further, because we have to ship the only three units that we have now and don't want to blow one up.

Do you design electronics? Do you simulate? Post something.

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John Larkin         Highland Technology, Inc 

lunatic fringe electronics
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Reply to
John Larkin

The Harrier isn't supersonic and in particular doesn't do super-cruise. There is a difference.

Reply to
krw

The ramp wasn't there for decoration.

Reply to
krw

They don't here. Delta has loads of 'em.

There are a couple of times more submarine crews than submarines, too.

Reply to
krw

It's not happening. So much for "simulations". Well, the simulations were designed to show flooded cities, so that's what they show. Reality doesn't care about simulations, however. It doesn't care about politics, either. Climate simulators do.

Reply to
krw

In particular, those simulations that show giant swings since the beginning of the industrial revolution. "Natural" climate change just won't do.

Just make it a sliding 12-year window and they're right. Armageddon is always 12 years away. In a billion or so years Sol will go nova and the ChickenLittles will be proven right.

Reply to
krw

For political advantage, of course.

Reply to
krw

whit3rd wrote:

What's the big deal with self-starting oscillators? An HC14 is self- starting. Here's a Classic Colpitts:

Version 4 SHEET 1 880 708 WIRE -96 -112 -160 -112 WIRE -32 -112 -96 -112 WIRE -32 -96 -32 -112 WIRE -160 -80 -160 -112 WIRE -576 -32 -608 -32 WIRE -496 -32 -576 -32 WIRE -336 -32 -416 -32 WIRE -240 -32 -336 -32 WIRE -224 -32 -240 -32 WIRE -336 -16 -336 -32 WIRE -608 0 -608 -32 WIRE -32 0 -32 -16 WIRE -336 64 -336 48 WIRE -160 64 -160 16 WIRE -160 64 -336 64 WIRE -128 64 -160 64 WIRE -112 64 -128 64 WIRE -336 80 -336 64 WIRE -160 80 -160 64 WIRE -608 96 -608 80 WIRE -336 160 -336 144 WIRE -160 176 -160 160 FLAG -32 0 0 FLAG -336 160 0 FLAG -128 64 Vout FLAG -240 -32 Q1B FLAG -608 96 0 FLAG -160 176 0 FLAG -96 -112 VCC FLAG -576 -32 VBB SYMBOL voltage -32 -112 R0 WINDOW 123 0 0 Left 2 WINDOW 0 33 33 Left 2 WINDOW 3 33 80 Left 2 SYMATTR InstName V2 SYMATTR Value 5V SYMATTR SpiceLine Rser=0 SYMBOL npn -224 -80 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL cap -352 -16 R0 SYMATTR InstName C1 SYMATTR Value 1.2732nF SYMBOL cap -352 80 R0 SYMATTR InstName C2 SYMATTR Value 1.2732nF SYMBOL ind -400 -16 M270 WINDOW 0 32 56 VTop 2 WINDOW 3 5 56 VBottom 2 WINDOW 39 -16 53 VBottom 2 SYMATTR InstName L1 SYMATTR Value 1.5915uh SYMATTR SpiceLine Rser=1.25 SYMBOL voltage -608 -16 R0 WINDOW 123 0 0 Left 2 WINDOW 0 33 33 Left 2 WINDOW 3 33 80 Left 2 SYMATTR InstName V1 SYMATTR Value 2.5V SYMATTR SpiceLine Rser=0 SYMBOL res -176 64 R0 SYMATTR InstName R1 SYMATTR Value 2.5k TEXT -400 -240 Left 2 !.tran 0 20u 0 50p TEXT -408 -264 Left 2 ;'Classic Colpitts This is from my Oscillator.zip article at

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Along with 11 other classes of oscillators. Most are self-starting, except for the fast-starting high-Q crystal oscillators. Complete design instructions are given, along with SPICE analysis guidelines.

Hint: start with Xl = 50 Ohms.

Reply to
Steve Wilson

On Sat, 22 Jun 2019 04:29:13 GMT, Steve Wilson wrote:

Here's my triggered 40 MHz oscillator.

Version 4 SHEET 1 1596 932 WIRE 128 48 -112 48 WIRE 240 48 128 48 WIRE 384 48 240 48 WIRE 576 48 480 48 WIRE 576 80 576 48 WIRE -112 96 -112 48 WIRE 128 96 128 48 WIRE 240 96 240 48 WIRE 576 192 576 160 WIRE 128 224 128 160 WIRE 240 224 240 176 WIRE 240 224 128 224 WIRE -112 240 -112 176 WIRE 480 256 480 48 WIRE 128 272 128 224 WIRE 384 288 384 48 WIRE 448 288 384 288 WIRE 608 288 528 288 WIRE 656 288 608 288 WIRE 448 320 384 320 WIRE 464 368 464 352 WIRE 496 368 496 352 WIRE 496 368 464 368 WIRE -32 384 -112 384 WIRE 128 384 128 352 WIRE 128 384 32 384 WIRE 272 384 128 384 WIRE 384 384 384 320 WIRE 384 384 272 384 WIRE 496 384 496 368 WIRE -112 448 -112 384 WIRE -112 576 -112 528 FLAG -112 240 0 FLAG -112 576 0 FLAG 608 288 CLK40 FLAG 272 384 RING FLAG 496 384 0 FLAG 576 192 0 SYMBOL ind 224 80 R0 WINDOW 0 73 43 Left 2 WINDOW 3 57 80 Left 2 SYMATTR InstName L1 SYMATTR Value 100n SYMBOL cap 112 96 R0 WINDOW 0 -66 29 Left 2 WINDOW 3 -77 68 Left 2 SYMATTR InstName C1 SYMATTR Value 150p SYMBOL voltage -112 80 R0 WINDOW 0 62 43 Left 2 WINDOW 3 62 87 Left 2 SYMATTR InstName V1 SYMATTR Value 1 SYMBOL res 112 256 R0 WINDOW 0 57 37 Left 2 WINDOW 3 55 72 Left 2 SYMATTR InstName R1 SYMATTR Value 50 SYMBOL voltage -112 432 R0 WINDOW 0 64 81 Left 2 WINDOW 3 30 124 Left 2 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V2 SYMATTR Value PULSE(0.1 3.3 10n 1n 1n 200n) SYMBOL Comparators\\LT1711 480 304 R0 WINDOW 0 107 30 Left 2 WINDOW 3 79 65 Left 2 SYMATTR InstName U1 SYMBOL voltage 576 64 R0 WINDOW 0 69 38 Left 2 WINDOW 3 67 68 Left 2 SYMATTR InstName V3 SYMATTR Value 3.3 SYMBOL diode 32 368 R90 WINDOW 0 -59 29 VBottom 2 WINDOW 3 -52 31 VTop 2 SYMATTR InstName D1 SYMATTR Value SMS7621 TEXT 768 352 Left 2 !.tran 300n TEXT 704 200 Left 2 ;Triggered Oscillator for TEXT 704 240 Left 2 ;TEM+ New_Sync Delay TEXT 744 288 Left 2 ;JL June 21, 2019 TEXT -24 456 Left 2 !.model SMS7621 D (Vfwd=0.3 Ron=10 Cjo=0.25p) TEXT 552 408 Left 2 ;TLV3501

This replaces a discontinued Maxim tapped silicon delay line. The triggered clock will go into an FPGA to fake out the delay line function.

Since it only needs to run for 5 cycles, it doesn't need a gain element.

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John Larkin         Highland Technology, Inc 

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Reply to
John Larkin

Think about Barkhausen, An oscillator is just a noise amplifier with positive feedback through some frequency selective stage. At temperatures above 0 K, there is always some input equivalent noise at the amplifier input. This noise is amplified, the broadband noise is then filtered and fed back to the input in correct phase, so that is amplified and filtered again and so on. The amplification must be greater than the filter losses. At least initially, the amplifier must operate in class A/AB so that the very small thermal noise is amplified, but can later on drop to class C when the oscillator is running.

,>This is from my Oscillator.zip article at

Most likely the crystal oscillator didn't start itself was that the Q was so high and hence the -3 dB bandwidth was so narrow that only a tiny fraction of the amplified broadband noise was fed back to amplifier input. More gain in the amplifier would most likely overcomed the crystal filter losses and oscillation would have started.

Reply to
upsidedown

Incidentally, that architecture was designed by fiddling with Spice. I didn't understand it until after the sim was working. I just tried a bunch of topologies based on hunches.

The real thing behaves a lot like the simulation, although it's not as energy efficient. The Cree model has some problems. Skin effect and dielectric losses are everywhere at these extremes. Everything gets hot, even barrier strips.

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John Larkin         Highland Technology, Inc 
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Reply to
John Larkin

No, if it has net positive gain, narrower bandwidth would just make it take longer to start.

If an oscillator will run but not start, there's a nonlinearity in the gain element.

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John Larkin         Highland Technology, Inc 
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Reply to
John Larkin

Depends on what kind. The HC14 makes an excellent self-starting oscillator.

Reply to
Steve Wilson

Not relevant. It starts and runs.

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John Larkin         Highland Technology, Inc 
picosecond timing   precision measurement  
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Reply to
John Larkin

John Larkin wrote:

Again, it depends on what kind of nonlinearity. You could not consider the HC14 to be a linear element. Yet it self-starts.

There is another kind of nonlinearity that will prevent an oscillator from starting. Here is an example. It converts the Classic Colpitts to a zero-cross limited oscillator. Changing R3 from 10k to 20k will prevent it from starting. There is not enough current to drive the LC tank for positive loop gain.

It is difficult to conceive of an oscillator that will run but not start.

But if you applied the fast start technique shown in my article, you might be able to start it and then keep it running by adjusting various parameters.

Do you have a better example?

Version 4 SHEET 1 880 708 WIRE -96 -112 -160 -112 WIRE -32 -112 -96 -112 WIRE 112 -112 -32 -112 WIRE -32 -96 -32 -112 WIRE -160 -80 -160 -112 WIRE -576 -32 -608 -32 WIRE -528 -32 -576 -32 WIRE -496 -32 -528 -32 WIRE -336 -32 -416 -32 WIRE -240 -32 -336 -32 WIRE -224 -32 -240 -32 WIRE -336 -16 -336 -32 WIRE -608 0 -608 -32 WIRE -32 0 -32 -16 WIRE 112 16 112 -112 WIRE -336 64 -336 48 WIRE -240 64 -336 64 WIRE -160 64 -160 16 WIRE -112 64 -160 64 WIRE -80 64 -112 64 WIRE 0 64 -16 64 WIRE 32 64 0 64 WIRE 48 64 32 64 WIRE -336 80 -336 64 WIRE -160 80 -160 64 WIRE -608 96 -608 80 WIRE 112 144 112 112 WIRE 160 144 112 144 WIRE 208 144 160 144 WIRE -336 160 -336 144 WIRE -160 176 -160 160 WIRE 112 176 112 144 WIRE -528 224 -528 -32 WIRE -112 224 -528 224 WIRE 0 224 0 64 WIRE 0 224 -32 224 WIRE 48 224 0 224 WIRE 112 288 112 272 WIRE -240 336 -240 64 WIRE 208 336 208 144 WIRE 208 336 -240 336 WIRE 208 368 208 336 WIRE 208 464 208 448 FLAG -32 0 0 FLAG -336 160 0 FLAG 160 144 Vout FLAG -240 -32 Q1B FLAG -608 96 0 FLAG -160 176 0 FLAG -96 -112 VCC FLAG -576 -32 VBB FLAG 112 288 0 FLAG -112 64 Q1E FLAG 32 64 Q2B FLAG 208 464 0 SYMBOL voltage -32 -112 R0 WINDOW 123 0 0 Left 2 WINDOW 0 33 33 Left 2 WINDOW 3 33 80 Left 2 SYMATTR InstName V2 SYMATTR Value 5V SYMATTR SpiceLine Rser=0 SYMBOL npn -224 -80 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL cap -352 -16 R0 SYMATTR InstName C1 SYMATTR Value 1.2732nF SYMBOL cap -352 80 R0 SYMATTR InstName C2 SYMATTR Value 1.2732nF SYMBOL ind -400 -16 M270 WINDOW 0 32 56 VTop 2 WINDOW 3 5 56 VBottom 2 WINDOW 39 -16 53 VBottom 2 SYMATTR InstName L1 SYMATTR Value 1.5915uh SYMATTR SpiceLine Rser=1.25 SYMBOL voltage -608 -16 R0 WINDOW 123 0 0 Left 2 WINDOW 0 33 33 Left 2 WINDOW 3 33 80 Left 2 SYMATTR InstName V1 SYMATTR Value 2.5V SYMATTR SpiceLine Rser=0 SYMBOL res -176 64 R0 SYMATTR InstName R1 SYMATTR Value 2.5k SYMBOL npn 48 16 R0 SYMATTR InstName Q2 SYMATTR Value 2N3904 SYMBOL cap -16 48 R90 WINDOW 0 0 32 VBottom 2 WINDOW 3 32 32 VTop 2 SYMATTR InstName C3 SYMATTR Value 1nf SYMBOL pnp 48 272 M180 SYMATTR InstName Q3 SYMATTR Value 2N3906 SYMBOL res -16 208 R90 WINDOW 0 0 56 VBottom 2 WINDOW 3 32 56 VTop 2 SYMATTR InstName R2 SYMATTR Value 100k SYMBOL res 192 352 R0 SYMATTR InstName R3 SYMATTR Value 10k TEXT -400 -240 Left 2 !.tran 0 30u 0 50p TEXT -408 -264 Left 2 ;'Classic Colpitts No Start

Reply to
Steve Wilson

On Jun 22, 2019, Steve Wilson wrote (in article):

Classic example is a regenerative frequency divider. "R. L. Miller (1939). "Fractional Frequency Generators Utilizing Regenerative Modulation". Proceedings of the IRE. 27 (7): 446-457. doi

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228513
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" .

Joe Gwinn

Reply to
Joseph Gwinn

Looks like deadband in Q2-Q3. Low gain at low swing.

You can build an oscillator with a tank and a comparator for gain. The comparator DC offset can rail it and prevent oscillation. Jog it a few millivolts and off it goes.

An unbiased bipolar or mosfet colpitts ditto, runs but won't start.

I recently posted an oscillator circuit that starts but doesn't run. I'm actually going to use it in a laser controller.

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John Larkin         Highland Technology, Inc 

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Reply to
John Larkin

Exactly. The opposite distortion from the HC14.

That is a limiter. Does it fit the definition of nonlinearity?

Probably won't run either.

That is not an oscillator. There is no feedback and no loop gain.

Reply to
Steve Wilson

They're an example of "nonlinear chaotic systems", that's all.

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Reply to
Jasen Betts

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