Twin T circuit wanted

I did one of those the other day. Works perfectly. 5V, 100A variable output. Jam a screwdriver on the output... all you'll get is a warm screwdriver. ;-)

Tim

The first few generations of RAM were designed before Spice existed, which you declared to be "not possible."

I don't know how to say that in Latin.

John

Of course I did. As I noted, I needed a very amplitude-stable sinewave source for the C5A inclinometer thing. This was a long time before DDS and DAC versions were feasible.

Can you think of other ways to make a very frequency and amplitude stable sine wave using early-70s technology? I suppose that a square wave generator and bandpass filter would work, but that's more parts.

Got any ideas?

John

Win, I don't mind the political banter that occurs here.

However, when circuits are tossed out here, and described "based on faith" (like most of Larkin's follies), I get just a wee bit perturbed.

"Picky, picky. To my mind, the base current robbed by the collector starves the base, lowering the CE stage's gain, until the exact equilibrium is achieved" is an _absolutely_incorrect_description_ of its operation.

Why don't you study it again and report back on how it actually works?

Hint: It IS a twist on a Rohde circuit, but Larkin can't cope with the quick example I threw out... since it had a capacitor in the emitter path.

In fact I think _most_ LC _low_distortion_ oscillators work on the real principle, NOT on "lowering the CE stage's gain".

Sheeesh! Win! I was looking forward to having the "master" unhinge some of Larkin's pomposity, but you blew it... BIG!

Another Hint: It's NOT "CE".

Sheeesh! Again!

Or should it be SHAME? ...Jim Thompson

You blew it big, John! Check out what I had to say to the "supposed master" :-) ...Jim Thompson

the

ent

e,

Use a PIC !

Larkin copies circuits from others, Rohde in this case, then totally blows the explanation.

Then, unfortunately, Win has backed up the BAD explanation :-( ...Jim Thompson

I didn't insult your wife... you did it yourself. ...Jim Thompson

I don't think so. People designed radar, magnetrons and klystrons and waveguides and servos and all that, without computers. They did the math. Early computers were obviously designed without help from computers.

I don't use Spice a lot, and could certainly get along without it. It is helpful when evaluating nonlinear systems, where math solutions get messy.

I think that most board-level designers use, and trust, Spice too much. Given the cost and time for IC fab, it makes sense for IC designers to use it to check their work before baking silicon. I don't think that Widlar used Spice.

John

Of course Widlar didn't use Spice. I didn't use Spice until around

Crystal oven? What did 'Tek' and HP use on their scopes for a reference?

But ALL modern radar and microwave innovations and technologies ARE computer model and simulation based, and could not be so without it. That includes things even as simple as waveguides, etc. Computer modeling has optimized every element of the entire spectrum of industries that are electronics related, much less the microwave niche.

Phased array radar is a perfect example.

Thanks for convicting yourself. You are guilty as charged, and your appeal will be denied, like you knew it would be.

What are you carrying on about?

OK, yes now I see, it's a common-base signal, excuse me, of course. And let's see, ahem, a reduction of the signal current into the LC resonator that reduces the amplitude. But it's a slightly awkward mental picture about exactly how that happens, especially right before lunch.

Now, what's this about a Rohde circuit?

Hehehehehee... He doesn't have enough hedges around his house?

Oh... wait...that's prUning... What? Same thing!? Well... almost. :-)

It definitely matches his persona here though. I wonder how many of his co-engineers have to carry the burden of some of what he flings around.

Hahah... Preener boy... Yeah... it fits him. A man can't even cuss in this hole here without a ditz like him accusing you of having a fetish. I think he has a few himself, and a few phobias as well. Sad.