Twin T circuit wanted

I always ran it with a big base capacitor. I'd expect that to prevent squegging, as the tank resonance/rectification thing should be 1st order, and 1st order loops are stable. A smaller base cap adds a second time-variant element in the right ballpark.

Sorry, can't remember values after 35 years.

John

What's your hourly rate? Send me a bill.

John

:-)

John

Usenet, and email, remove the emotional feedbacks you get in person, or even over the telephone. That makes for some pathological behavior. And people develop personnas that may not represent how they are in real life. I wonder if anyone has published stuff about this.

John

Ever seen two cats fighting with each other through the window glass? They enjoy the process while staying completely safe. That reminds me a lot of usenet or web forums.

VLV

=3D 120mV

hat

ed

If you don't mind, I prefer "barbarian."

James

Me too, esp. for lossy inductors. Increase the bias--that fixes it, for a number of reasons.

-- Cheers, James Arthur

Yup, only some people aren't as amart as cats and take it seriously.

John

Can we settle on "un-mutual"?

John

old "Prisoner" fan

Late at night, by candle light, John Larkin penned this immortal opus:

Ok, here's my take on it. It does seem to work class C, with some weird twists. The base is held practically constant, Q1 starts conducting when the emitter is pulled below Vb-.6V. As the tank gets close to Ve, there's a bit of suckage through bc, Vc ~= Ve. Then there's another bit of kick, Ve goes up and turns off Q1.

Depending on turns ratio Vb stabilizes somewhere between 0.5 and

-0.2V. A higher TR pulls it lower, makes sense.

Adding about 1 or more ohms to L's Rs sets it squegging, haven't got that really figured yet.

I start saving data after it has settled to make the currents easier resolved on the graph.

Version 4 SHEET 1 880 680 WIRE 304 -64 16 -64 WIRE 432 -64 304 -64 WIRE 304 -32 304 -64 WIRE 400 -32 304 -32 WIRE 304 0 304 -32 WIRE 400 0 400 -32 WIRE 16 16 16 -64 WIRE 256 96 176 96 WIRE 304 96 304 64 WIRE 304 96 256 96 WIRE 400 96 400 80 WIRE 400 96 304 96 WIRE 176 144 176 96 WIRE 432 160 432 -64 WIRE 16 192 16 96 WIRE 64 192 16 192 WIRE 112 192 64 192 WIRE 208 240 176 240 WIRE 352 240 208 240 WIRE 16 256 16 192 WIRE 432 272 432 240 WIRE 352 304 352 240 WIRE 16 352 16 320 WIRE 352 416 352 384 FLAG 16 352 0 FLAG 352 416 0 FLAG 432 272 0 FLAG 256 96 c FLAG 64 192 b FLAG 208 240 e SYMBOL voltage 432 144 R0 WINDOW 123 0 0 Left 0 WINDOW 39 0 0 Left 0 SYMATTR InstName V1 SYMATTR Value 5 SYMBOL npn 112 144 R0 SYMATTR InstName Q1 SYMATTR Value 2N3904 SYMBOL ind2 384 -16 R0 SYMATTR InstName L1 SYMATTR Value 10m SYMBOL ind2 336 400 M180 WINDOW 0 36 80 Left 0 WINDOW 3 36 40 Left 0 SYMATTR InstName L2 SYMATTR Value 25µ SYMATTR SpiceLine Rser=30m SYMBOL res 0 0 R0 SYMATTR InstName R1 SYMATTR Value 100k SYMBOL cap 288 0 R0 SYMATTR InstName C1 SYMATTR Value 1µ SYMATTR SpiceLine Rser=10m SYMBOL cap 0 256 R0 SYMATTR InstName C2 SYMATTR Value 1µ SYMATTR SpiceLine Rser=10m TEXT 224 152 Left 0 !K1 L1 L2 1 TEXT -8 392 Left 0 !.tran 0 100m 5m TEXT 128 296 Left 0 !.opt plotwinsize 0

- YD.

"Munbling"? I don't know... it is not a word that I am aware of.

Since you were the one that used it, maybe you could tell us.

Late at night, by candle light, Robert Baer penned this immortal opus:

:-D

- YD.

I did that in this circuit. Two stage though, since it has DC feedback.

The feedback winding needs a very small voltage to keep the hysteresis band less than P-P current (i.e., keep it in CCM). Too small, of course, and it turns class C, then class A, then not oscillating at all, at which point it's just a boring two-diode-biased current source with extra parts.

Despite the fairly large number of turns on the inductor, you can see it hardly takes any secondary at all to run.

Tim

Here's one for free:

Or here's an application of a squegging oscillator:

LT doesn't like all the SYMATTR use. It expects to only see it once.

Thanks, John. I like the bong! But it's a little on the long side tho, don'cha think? That's one problem with perfect inductors and capacitors, too high Q. How about adding some esr loss for the inductor, or a parallel resistor on the LC tank?

I wonder, don't we need a bypass capacitor on Q2, the oscillator-supply voltage emitter follower? Check out the waveform there. And of course, then we'll need a Q2 base resistor to help stop the RF oscillation thing - you know, the old emitter-follower with cap load, etc.

Thanks! Sounds nice - now, whereinthehell is the icon for a "bongy" face? :-)))

Ed

It's recursive mumbling, the sound you make when you mumble "mumble."

John

Yes, John... muMble is a word.

"muNble", which is what you wrote, is not, idiot.