John Larkin's LC oscillator, John Fields' simulation
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From: ehsjr on 14 Jun 2010 13:32 John Fields wrote: > On 14 Jun 2010 04:08:08 -0700, Winfield Hill > <Winfield_member(a)newsguy.com> wrote: > > >>John Fields wrote... >> >>>Winfield Hill wrote: >>> >>>>John Fields wrote... >>>> >>>>>On Fri, 11 Jun 2010 07:02:03 -0500, John Fields wrote: >>>>> >>>>>>On 10 Jun 2010 13:23:55 -0700, Winfield Hill 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: [ big snip ] >>>> >>>>Thanks, John. I like the bong! [snip] >>> >>>--- >>>Sorry for the delay... >>> >>>Better yet, I chose a real-world inductor, included the specified >>>parasitic R, and added, arbitrarily, an ohm as the ESR for the cap >>>since I was too lazy to go shopping for that. >> >>Excellent. >> >> >>>Here's the circuit, oscillating at around 675Hz. >>>Sounds pretty good, I think, and the bong doesn't >>>last as long as it used to. >> >>I didn't see, what did you change to lower the Q? > > > --- > The wire resistance of L1 and the ESR of C1. > Right click on the components and a little dialogue will pop up which > can be edited to modify the component attributes. > --- > > >>I had meant to suggest tying a series resistor on >>Q1's emitter signal path. > > > --- > It does little more than attenuate the initial amplitude of the bong > and disturb its symmetry, so the rate of decay seems to be controlled > by the current C3 supplies into R2 and the base of Q3 after Q2 turns > off. > > With C3 being 7.5�F and zero leakage, the range of decay varies from > 1.9s with R2 open to 0.4s with R2 = 50k. > --- > > >>John Larkin commented that the ringdown was more >>due to the LC's stored energy than Q1's amplifying >>role. I wonder, if you took the same LC, ignore >>your new secondary, leave out Q1, etc., and you >>gave it a short current spike to get it started, >>what would the result look like? > > > > Something like this, I'd suspect: > --- > Version 4 > SHEET 1 936 680 > WIRE -704 16 -752 16 > WIRE -592 16 -624 16 > WIRE -448 16 -512 16 > WIRE -448 64 -448 16 > WIRE -352 64 -448 64 > WIRE -448 80 -448 64 > WIRE -352 80 -352 64 > WIRE -752 96 -752 16 > WIRE -576 96 -576 64 > WIRE -448 176 -448 144 > WIRE -352 176 -352 160 > WIRE -352 176 -448 176 > WIRE -752 224 -752 176 > WIRE -576 224 -576 176 > WIRE -576 224 -752 224 > WIRE -528 224 -528 64 > WIRE -528 224 -576 224 > WIRE -448 224 -448 176 > WIRE -448 224 -528 224 > WIRE -752 320 -752 224 > FLAG -752 320 0 > SYMBOL ind2 -368 64 R0 > SYMATTR InstName L1 > SYMATTR Value 5.6e-3 > SYMATTR Type ind > SYMBOL cap -464 80 R0 > SYMATTR InstName C1 > SYMATTR Value 10e-6 > SYMBOL voltage -752 80 R0 > WINDOW 123 0 0 Left 0 > WINDOW 39 0 0 Left 0 > WINDOW 0 -44 8 Left 0 > WINDOW 3 -26 108 Left 0 > SYMATTR InstName V2 > SYMATTR Value 5 > SYMBOL voltage -576 80 R0 > WINDOW 0 -45 9 Left 0 > WINDOW 3 -242 110 Invisible 0 > WINDOW 123 0 0 Left 0 > WINDOW 39 0 0 Left 0 > SYMATTR InstName V3 > SYMATTR Value PULSE(0 1 .1 1E-6 1E-6 1e-2) > SYMBOL sw -496 16 M270 > WINDOW 0 32 15 Left 0 > WINDOW 3 32 44 Left 0 > SYMATTR InstName S1 > SYMBOL res -608 0 R90 > WINDOW 0 0 56 VBottom 0 > WINDOW 3 32 56 VTop 0 > SYMATTR InstName R1 > SYMATTR Value 1 > TEXT -672 256 Left 0 !.model SW SW(Ron=.01 Roff=1000Meg Vt=0.5Vh=0) > TEXT -664 288 Left 0 !.tran 1 uic > > Zoom in on the current through R1 at about 1ms and you'll see smething ^ 100ms > pretty neat. :-) > > JF Nice. Ed
From: John Fields on 14 Jun 2010 20:44
On Mon, 14 Jun 2010 13:32:36 -0400, ehsjr <ehsjr(a)nospamverizon.net> wrote: >John Fields wrote: >> On 14 Jun 2010 04:08:08 -0700, Winfield Hill >> <Winfield_member(a)newsguy.com> wrote: >> >> >>>John Fields wrote... >>> >>>>Winfield Hill wrote: >>>> >>>>>John Fields wrote... >>>>> >>>>>>On Fri, 11 Jun 2010 07:02:03 -0500, John Fields wrote: >>>>>> >>>>>>>On 10 Jun 2010 13:23:55 -0700, Winfield Hill 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: [ big snip ] >>>>> >>>>>Thanks, John. I like the bong! [snip] >>>> >>>>--- >>>>Sorry for the delay... >>>> >>>>Better yet, I chose a real-world inductor, included the specified >>>>parasitic R, and added, arbitrarily, an ohm as the ESR for the cap >>>>since I was too lazy to go shopping for that. >>> >>>Excellent. >>> >>> >>>>Here's the circuit, oscillating at around 675Hz. >>>>Sounds pretty good, I think, and the bong doesn't >>>>last as long as it used to. >>> >>>I didn't see, what did you change to lower the Q? >> >> >> --- >> The wire resistance of L1 and the ESR of C1. >> Right click on the components and a little dialogue will pop up which >> can be edited to modify the component attributes. >> --- >> >> >>>I had meant to suggest tying a series resistor on >>>Q1's emitter signal path. >> >> >> --- >> It does little more than attenuate the initial amplitude of the bong >> and disturb its symmetry, so the rate of decay seems to be controlled >> by the current C3 supplies into R2 and the base of Q3 after Q2 turns >> off. >> >> With C3 being 7.5�F and zero leakage, the range of decay varies from >> 1.9s with R2 open to 0.4s with R2 = 50k. >> --- >> >> >>>John Larkin commented that the ringdown was more >>>due to the LC's stored energy than Q1's amplifying >>>role. I wonder, if you took the same LC, ignore >>>your new secondary, leave out Q1, etc., and you >>>gave it a short current spike to get it started, >>>what would the result look like? >> >> >> >> Something like this, I'd suspect: >> --- >> Version 4 >> SHEET 1 936 680 >> WIRE -704 16 -752 16 >> WIRE -592 16 -624 16 >> WIRE -448 16 -512 16 >> WIRE -448 64 -448 16 >> WIRE -352 64 -448 64 >> WIRE -448 80 -448 64 >> WIRE -352 80 -352 64 >> WIRE -752 96 -752 16 >> WIRE -576 96 -576 64 >> WIRE -448 176 -448 144 >> WIRE -352 176 -352 160 >> WIRE -352 176 -448 176 >> WIRE -752 224 -752 176 >> WIRE -576 224 -576 176 >> WIRE -576 224 -752 224 >> WIRE -528 224 -528 64 >> WIRE -528 224 -576 224 >> WIRE -448 224 -448 176 >> WIRE -448 224 -528 224 >> WIRE -752 320 -752 224 >> FLAG -752 320 0 >> SYMBOL ind2 -368 64 R0 >> SYMATTR InstName L1 >> SYMATTR Value 5.6e-3 >> SYMATTR Type ind >> SYMBOL cap -464 80 R0 >> SYMATTR InstName C1 >> SYMATTR Value 10e-6 >> SYMBOL voltage -752 80 R0 >> WINDOW 123 0 0 Left 0 >> WINDOW 39 0 0 Left 0 >> WINDOW 0 -44 8 Left 0 >> WINDOW 3 -26 108 Left 0 >> SYMATTR InstName V2 >> SYMATTR Value 5 >> SYMBOL voltage -576 80 R0 >> WINDOW 0 -45 9 Left 0 >> WINDOW 3 -242 110 Invisible 0 >> WINDOW 123 0 0 Left 0 >> WINDOW 39 0 0 Left 0 >> SYMATTR InstName V3 >> SYMATTR Value PULSE(0 1 .1 1E-6 1E-6 1e-2) >> SYMBOL sw -496 16 M270 >> WINDOW 0 32 15 Left 0 >> WINDOW 3 32 44 Left 0 >> SYMATTR InstName S1 >> SYMBOL res -608 0 R90 >> WINDOW 0 0 56 VBottom 0 >> WINDOW 3 32 56 VTop 0 >> SYMATTR InstName R1 >> SYMATTR Value 1 >> TEXT -672 256 Left 0 !.model SW SW(Ron=.01 Roff=1000Meg Vt=0.5Vh=0) >> TEXT -664 288 Left 0 !.tran 1 uic >> >> Zoom in on the current through R1 at about 1ms and you'll see smething > ^ > 100ms >> pretty neat. :-) >> >> JF > >Nice. > >Ed --- Aarghhhh!!! Good catch, thanks. :-) |