John Larkin's LC oscillator
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From: John Larkin on 11 Jun 2010 22:56 On Fri, 11 Jun 2010 10:38:51 -0700, Robert Baer <robertbaer(a)localnet.com> wrote: >BlindBaby wrote: >> On Fri, 11 Jun 2010 09:14:34 -0700, John Larkin >> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >> >>> On Fri, 11 Jun 2010 09:09:29 -0700, BlindBaby >>> <BlindMelonChitlin(a)wellnevergetthatonethealbumcover.org> wrote: >>> >>>> On Fri, 11 Jun 2010 08:37:43 -0700, John Larkin >>>> <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >>>> >>>>> On Fri, 11 Jun 2010 17:15:50 +0200, Jeroen Belleman >>>>> <jeroen(a)nospam.please> wrote: >>>>> >>>>>> John Larkin wrote: >>>>>>> I like the way it works with a very high turns ratio, very small AC >>>>>>> drive at the emitter. But at lower ratios, it gets very nonlinear and >>>>>>> becomes, if that means anything, a tuned blocking oscillator. The base >>>>>>> capacitor value would be lowered so that the cap recharges a bunch >>>>>>> during a oscillatory cycle. >>>>>>> >>>>>>> I'm sure JT and JF will spend the next week diligently searching for a >>>>>>> set of values that will make my circuit not work. Then they'll crow, >>>>>>> or rather, cluck about it. That's OK: as Woody Allen says, we need the >>>>>>> eggs. >>>>>> I made it squeg. Maybe that will please them. >>>>>> >>>>>> Jeroen Belleman >>>>> >>>>> Sloman is our resident squegging expert. >>>>> >>>>> John >>>> >>>> We should take a poll as to what attribute you are an expert in. >>>> >>>> I don't think it would result in the same determination that you >>>> obviously think it would. >>> Do you know what squegging means? Tell us. >> >> I have characterized a lot of oscillator circuits at the bench, John. >> Remember... power supplies... That was years ago. Now it is what the >> power supplies power. Still lots of oscillators though. >> >>> There are maybe two usages, both electronic, >> >> I have very little faith in your word derivative/origin declarations, >> John. That is aside from the fact that I am familiar with the word. >> Remember? I work in this industry. >> >>> but one of them is >>> obscure, >> >> Perhaps only in your thinking. >> >>> and the other is even more obscure. >> >> Certainly only in your thinking. > Well, now, if both usages are NOT obscure (and i know of only one and >have been a tech for at least 50 years),please TELL US the source / >creation of the word and the context in each case. > That way we will know that you are not just doing a fantasy trip. Everybody must know the less obscure case by now. The more obscure case: In the toob days, sometimes TV sets would have vertical bars on the screen. It was caused by Barkhausen oscillations in the horiz output tube, getting back into the RF input. Some TV techs called that "squegging." I have no idea of the source of the word. John
From: John Larkin on 11 Jun 2010 23:04 On Fri, 11 Jun 2010 08:16:29 -0500, John Fields <jfields(a)austininstruments.com> wrote: >On Fri, 11 Jun 2010 07:02:03 -0500, John Fields ><jfields(a)austininstruments.com> wrote: > >>On 10 Jun 2010 13:23:55 -0700, Winfield Hill >><Winfield_member(a)newsguy.com> wrote: >> >> >>> In a ringing bell application, as the supply voltage sags, >>> and the amplitude drops, I imagine the circuit will move >>> from class C back to class A operation, before stopping. >> >>--- >>Why imagine? >> >>Here's a circuit list that'll show it all _and_ it'll create a .wav >>file, "bong.wav" in whatever folder the cicuit's in, so you can hear >>it. >> >>Enjoy! :-) > >--- >Oops... >Here it is: > >Version 4 >SHEET 1 936 680 >WIRE -384 48 -592 48 >WIRE -320 48 -384 48 >WIRE -112 48 -224 48 >WIRE 16 48 -112 48 >WIRE 112 48 16 48 >WIRE 16 64 16 48 >WIRE 112 64 112 48 >WIRE -384 96 -384 48 >WIRE -112 96 -112 48 >WIRE -448 144 -496 144 >WIRE 16 160 16 128 >WIRE 112 160 112 144 >WIRE 112 160 16 160 >WIRE -496 176 -496 144 >WIRE -592 192 -592 48 >WIRE -272 192 -272 112 >WIRE -272 192 -384 192 >WIRE 16 192 16 160 >WIRE -112 240 -112 176 >WIRE -48 240 -112 240 >WIRE -384 272 -384 192 >WIRE -272 272 -272 192 >WIRE -496 288 -496 256 >WIRE -112 304 -112 240 >WIRE 16 320 16 288 >WIRE 112 320 16 320 >WIRE 16 336 16 320 >WIRE 112 336 112 320 >WIRE -592 432 -592 272 >WIRE -496 432 -496 368 >WIRE -496 432 -592 432 >WIRE -384 432 -384 352 >WIRE -384 432 -496 432 >WIRE -272 432 -272 336 >WIRE -272 432 -384 432 >WIRE -112 432 -112 368 >WIRE -112 432 -272 432 >WIRE 16 432 16 416 >WIRE 16 432 -112 432 >WIRE 112 432 112 416 >WIRE 112 432 16 432 >WIRE -592 528 -592 432 >FLAG -592 528 0 >SYMBOL ind2 96 48 R0 >SYMATTR InstName L1 >SYMATTR Value 20e-3 >SYMATTR Type ind >SYMBOL ind2 96 432 M180 >WINDOW 0 36 80 Left 0 >WINDOW 3 36 40 Left 0 >SYMATTR InstName L2 >SYMATTR Value 500e-6 >SYMATTR Type ind >SYMATTR SpiceLine Rser=.01 >SYMBOL npn -48 192 R0 >SYMATTR InstName Q1 >SYMATTR Value 2N3904 >SYMBOL res -128 80 R0 >SYMATTR InstName R1 >SYMATTR Value 100k >SYMBOL cap 0 64 R0 >SYMATTR InstName C1 >SYMATTR Value 10e-6 >SYMBOL voltage -592 176 R0 >WINDOW 123 0 0 Left 0 >WINDOW 39 0 0 Left 0 >WINDOW 3 24 104 Invisible 0 >SYMATTR Value 5 >SYMATTR InstName V2 >SYMBOL pnp -448 192 M180 >SYMATTR InstName Q3 >SYMATTR Value 2N4403 >SYMBOL voltage -496 272 R0 >WINDOW 123 0 0 Left 0 >WINDOW 39 0 0 Left 0 >WINDOW 3 24 104 Invisible 0 >SYMATTR Value PULSE(5 0 0 1e-6 1e-6 .01) >SYMATTR InstName V1 >SYMBOL npn -320 112 R270 >SYMATTR InstName Q2 >SYMATTR Value 2N3904 >SYMBOL cap -288 272 R0 >SYMATTR InstName C4 >SYMATTR Value 1e-6 >SYMBOL res -400 256 R0 >SYMATTR InstName R2 >SYMATTR Value 100k >SYMBOL res -512 160 R0 >SYMATTR InstName R3 >SYMATTR Value 1000 >SYMBOL cap -128 304 R0 >SYMATTR InstName C2 >SYMATTR Value 1e-7 >SYMBOL res 0 320 R0 >SYMATTR InstName R4 >SYMATTR Value 750 >TEXT 32 184 Left 0 !K1 L1 L2 1 >TEXT -528 464 Left 0 !.tran 5 >TEXT -528 496 Left 0 !.wave .\\bong.wav 8 10000 N008 The .wav thing is cute. But the ringdown is being caused by the LC's Q, not by the transistor oscillation. The R2-C4 thing dies out pretty soon, and then the tank rings on its own. That why you need R4; at infinite Q, it would ring forever. If you can get an LC with a Q that high, you can simulate a nice bell noise by just whacking it and letting it ring... like a real brass bell. Much simpler. John
From: BlindBaby on 11 Jun 2010 23:06 On Fri, 11 Jun 2010 20:04:42 -0700, John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> wrote: >On Fri, 11 Jun 2010 08:16:29 -0500, John Fields ><jfields(a)austininstruments.com> wrote: > >>On Fri, 11 Jun 2010 07:02:03 -0500, John Fields >><jfields(a)austininstruments.com> wrote: >> >>>On 10 Jun 2010 13:23:55 -0700, Winfield Hill >>><Winfield_member(a)newsguy.com> wrote: >>> >>> >>>> In a ringing bell application, as the supply voltage sags, >>>> and the amplitude drops, I imagine the circuit will move >>>> from class C back to class A operation, before stopping. >>> >>>--- >>>Why imagine? >>> >>>Here's a circuit list that'll show it all _and_ it'll create a .wav >>>file, "bong.wav" in whatever folder the cicuit's in, so you can hear >>>it. >>> >>>Enjoy! :-) >> >>--- >>Oops... >>Here it is: >> >>Version 4 >>SHEET 1 936 680 >>WIRE -384 48 -592 48 >>WIRE -320 48 -384 48 >>WIRE -112 48 -224 48 >>WIRE 16 48 -112 48 >>WIRE 112 48 16 48 >>WIRE 16 64 16 48 >>WIRE 112 64 112 48 >>WIRE -384 96 -384 48 >>WIRE -112 96 -112 48 >>WIRE -448 144 -496 144 >>WIRE 16 160 16 128 >>WIRE 112 160 112 144 >>WIRE 112 160 16 160 >>WIRE -496 176 -496 144 >>WIRE -592 192 -592 48 >>WIRE -272 192 -272 112 >>WIRE -272 192 -384 192 >>WIRE 16 192 16 160 >>WIRE -112 240 -112 176 >>WIRE -48 240 -112 240 >>WIRE -384 272 -384 192 >>WIRE -272 272 -272 192 >>WIRE -496 288 -496 256 >>WIRE -112 304 -112 240 >>WIRE 16 320 16 288 >>WIRE 112 320 16 320 >>WIRE 16 336 16 320 >>WIRE 112 336 112 320 >>WIRE -592 432 -592 272 >>WIRE -496 432 -496 368 >>WIRE -496 432 -592 432 >>WIRE -384 432 -384 352 >>WIRE -384 432 -496 432 >>WIRE -272 432 -272 336 >>WIRE -272 432 -384 432 >>WIRE -112 432 -112 368 >>WIRE -112 432 -272 432 >>WIRE 16 432 16 416 >>WIRE 16 432 -112 432 >>WIRE 112 432 112 416 >>WIRE 112 432 16 432 >>WIRE -592 528 -592 432 >>FLAG -592 528 0 >>SYMBOL ind2 96 48 R0 >>SYMATTR InstName L1 >>SYMATTR Value 20e-3 >>SYMATTR Type ind >>SYMBOL ind2 96 432 M180 >>WINDOW 0 36 80 Left 0 >>WINDOW 3 36 40 Left 0 >>SYMATTR InstName L2 >>SYMATTR Value 500e-6 >>SYMATTR Type ind >>SYMATTR SpiceLine Rser=.01 >>SYMBOL npn -48 192 R0 >>SYMATTR InstName Q1 >>SYMATTR Value 2N3904 >>SYMBOL res -128 80 R0 >>SYMATTR InstName R1 >>SYMATTR Value 100k >>SYMBOL cap 0 64 R0 >>SYMATTR InstName C1 >>SYMATTR Value 10e-6 >>SYMBOL voltage -592 176 R0 >>WINDOW 123 0 0 Left 0 >>WINDOW 39 0 0 Left 0 >>WINDOW 3 24 104 Invisible 0 >>SYMATTR Value 5 >>SYMATTR InstName V2 >>SYMBOL pnp -448 192 M180 >>SYMATTR InstName Q3 >>SYMATTR Value 2N4403 >>SYMBOL voltage -496 272 R0 >>WINDOW 123 0 0 Left 0 >>WINDOW 39 0 0 Left 0 >>WINDOW 3 24 104 Invisible 0 >>SYMATTR Value PULSE(5 0 0 1e-6 1e-6 .01) >>SYMATTR InstName V1 >>SYMBOL npn -320 112 R270 >>SYMATTR InstName Q2 >>SYMATTR Value 2N3904 >>SYMBOL cap -288 272 R0 >>SYMATTR InstName C4 >>SYMATTR Value 1e-6 >>SYMBOL res -400 256 R0 >>SYMATTR InstName R2 >>SYMATTR Value 100k >>SYMBOL res -512 160 R0 >>SYMATTR InstName R3 >>SYMATTR Value 1000 >>SYMBOL cap -128 304 R0 >>SYMATTR InstName C2 >>SYMATTR Value 1e-7 >>SYMBOL res 0 320 R0 >>SYMATTR InstName R4 >>SYMATTR Value 750 >>TEXT 32 184 Left 0 !K1 L1 L2 1 >>TEXT -528 464 Left 0 !.tran 5 >>TEXT -528 496 Left 0 !.wave .\\bong.wav 8 10000 N008 > > >The .wav thing is cute. But the ringdown is being caused by the LC's >Q, not by the transistor oscillation. The R2-C4 thing dies out pretty >soon, and then the tank rings on its own. That why you need R4; at >infinite Q, it would ring forever. > >If you can get an LC with a Q that high, you can simulate a nice bell >noise by just whacking it and letting it ring... like a real brass >bell. Much simpler. > >John One ringy dingy.
From: John Devereux on 12 Jun 2010 03:53 John Larkin <jjlarkin(a)highNOTlandTHIStechnologyPART.com> writes: > On Fri, 11 Jun 2010 17:43:39 -0300, YD <ydtechHAT(a)techie.com> wrote: > >>Late at night, by candle light, John Larkin >><jjlarkin(a)highNOTlandTHIStechnologyPART.com> penned this immortal >>opus: [...] > > That's nice. It's running pretty hard class C. > > Try this: > > C2 = 10 uF > L2 = 0.25 uH > > That will move it to class A, with about 50 millivolts p-p drive at > the emitter. That's more like what I had in mind originally. Vb is > stiff at about +0.6, and Vc dips down to about -0.1, a little below > Ve, sucking a brief blip of current out of the base cap. The sine wave > is just slightly flattened on the bottom. > > It's useful to add a small resistor, like 1 milliohm, in the emitter > so that you can probe the current. It's interesting. Hi John, You don't need to add the the resistor. You can just measure the emitter current by clicking on it! > > I measure the amplitude at the collector at 10.11 p-p, pretty close to > 2*Vcc. > > ftp://jjlarkin.lmi.net/LC_YDx.gif > > John > > > -- John Devereux
From: Jasen Betts on 12 Jun 2010 04:39
On 2010-06-11, BlindBaby <BlindMelonChitlin(a)wellnevergetthatonethealbumcover.org> wrote: > On Fri, 11 Jun 2010 08:16:29 -0500, John Fields ><jfields(a)austininstruments.com> wrote: > .... >>SYMBOL res -400 256 R0 >>SYMATTR InstName R2 >>SYMATTR Value 100k >>SYMBOL res -512 160 R0 >>SYMATTR InstName R3 >>SYMATTR Value 1000 >>SYMBOL cap -128 304 R0 >>SYMATTR InstName C2 >>SYMATTR Value 1e-7 >>SYMBOL res 0 320 R0 >>SYMATTR InstName R4 >>SYMATTR Value 750 >>TEXT 32 184 Left 0 !K1 L1 L2 1 >>TEXT -528 464 Left 0 !.tran 5 >>TEXT -528 496 Left 0 !.wave .\\bong.wav 8 10000 N008 > > LT doesn't like all the SYMATTR use. It expects to only see it once. Works fine here. version 4.07q --- news://freenews.netfront.net/ - complaints: news(a)netfront.net --- |