Cute amplifier - bootstrapped

use a series input resistor for voltage to current conversion.

Aha! We've entered the "Larkin excuse phase" >:-}

He'll never accept that he is wrong. I await his "analysis", but it'll never happen... he's not competent to do it.

In...

Message-ID: Subject: Re: Cute amplifier - bootstrapped From: snipped-for-privacy@yahoo.com

James admitted that C2 is actually a capacitive transducer and that his original intent was not to make a general purpose amplifier. ...Jim Thompson

use a series input resistor for voltage to current conversion.

All amps are at the mercy of the signal source impedance. Generator impedance and amp input impedance make a voltage divider. No news there. The input cap is small because it's actually a capacitive transducer.

It's fine for audio with bigger caps. And it's apparently fine for what James wants to do, where the first cap is the capacitive transducer. James is trying to maximize the forward gain, and Fred and Jim are determined to not understand that and in fact reduce it, their end game being to show how smart they are and how dumb everybody else is. It's not working.

My PNP version has 57 dB of voltage gain, which is cool.

you use a series input resistor for voltage to current conversion.

Wrong about what? Jame's circuit works, and the bootstrap increases the forward gain by over 10:1. If you dispute that, you are being the senile ass that you usually are.

I still can't figure out your statement

Sounds like you're hitting your bottle-and-a-half wine quota early in the day.

Idiot!

So much for hand-waving. I peeled off the input stage, applied bias to the bottom of R2 via a 10000000H inductor.

The "bootstrap" impedance looking into that node looks like a bandpass centered at 27.419KHz, BW of 57KHz, peak impedance of 428K (real part).

Impedance at 1KHz is ~24.5K. ...Jim Thompson

you use a series input resistor for voltage to current conversion.

No they aren't.

Which is why one generally makes the input impedance large enough to make source impedance insignificant.

That has been suggested but since he's never said what the amp is for you don't really know and that's not the only cap. Unless the amp is intended for above the audio band operation then the 'maximum gain' you speak of is compromised because the bootstrap cap is a low value.

I just said that, although one should define the input impedance so gain doesn't go flying all over the place depending on what you plug into it.

The original amp takes the converse route of a high feedback resistor but that compromises the DC bias feedback.

If you 'really' want maximum gain with undefined source impedances then AC bypass the DC bias feedback.

I haven't heard him say what it is he 'wants to do'. What I heard him say is it's a cute bootstrapped amp.

I do note he mentioned 40 kHz, but initially missed the feedback aspect. The boostrap is clearly what he found 'cute', as did I when first seen.

You're both so interested in one-upmanship that you never hear what the other is saying,

Assuming your methodology was valid, that's one heck of an increase over the 20k (max) it would otherwise be, wouldn't you say?

understand

and

Yes it is >:-}

And James has said that the "input cap" is actually a transducer...

Nope. I'm right and Larkin has his narcissistic head up his butt.

So show us the "PNP version".

I'll post a hybrid-pi analysis later... off to a movie and dinner ;-) ...Jim Thompson

understand

and

So you admit that the 'cute amp' is perfectly fine as is.

He says it works and now you say it works. Just what is it you are 'right' about?

you use a series input resistor for voltage to current conversion.

understand

and

Not so. I liked James' circuit, agreed that it was cute, and picked it up and riffed on another version, the PNP thing. All friendly and constructive. James' post led to some broader discussion of the virtues of bootstrapping, ditto friendly and constructive and possibly valuable to some readers. James and I like to play with circuits. So does Phil.

Fred and Jim went all negative from the start, trashing a circuit instead of trying to understand it, much less improve it.

Be constructive: contribute something yourself.

Jim just posted a "mathematical analysis" (ie, more Spice fiddling) showing that the bootstrap does indeed increase the load impedance that the NPN sees. Which was James's point from the start.

understand

and

I posted it, you pathetic moron. This is not the first time you've complained about my not posting stuff, after you've killfiled me.

Have another bottle of wine at the Olive Garden or Applebees or whatever.

I wish you would tell us what this is for, at least in terms of gain, bandwidth, and load.

you use a series input resistor for voltage to current conversion.

to

understand

and

I already did "contribute something" but if it would make you feel better I can post my microphone preamp version.

that

Yes, I saw it.

understand

and

Arthur's use of it where the "input" cap is actually the transducer and NOT suitable for a voltage input... sure it "works", but nothing I'd write home about.

Too "relaxed" >:-} Analysis tomorrow. ...Jim Thompson

you use a series input resistor for voltage to current conversion.

to

understand

and

James'

that

Larkin is sure one sick puppy. ...Jim Thompson

It's the "poor man's gyrator"... not a proper implementation of a general purpose bootstrap.

Take it for whatever you want. I really don't care. Feed a village idiot garbage... ...Jim Thompson

snipped-for-privacy@gmail.com

unless you use a series input resistor for voltage to current conversion.

to

understand

and

James'

that

Which

I understood James's circuit the instant I saw it, and posted an (improved?) riff on it. You took days to get it pounded into your calcified skull that it actually works the way he said it works.

You dared me to post my PNP circuit days after I actually did, but you never saw it because you claim to have killfiled me. That's plain idiotic. You "killfile" me and hang on my every post, responding to followups. You threaten to do "mathematical analysis" and follow up with a trivial, predictable Spice measurement.

And you call me sick?

Geez, the Niners are going to the Super Bowl. I hear serious fireworks outside. Do you have a football team in Arizona? The Tuscon Turtles or something?

We did lose out to Scottsdale recently in another competition.

Of course you care. You were wrong in public. Again.

bandwidth, and load.

What it is for is quite obvious and that is to get a ruckus going, and by all accounts, it's working !

Good job..

Jamie

bandwidth, and load.

LOL