AMZ Mosfet Booster - some questions

[Whoops]

Hi,
I was checking the AMZ Mosfet Booster circuit from jack Orman and have some questions that would like to ask you guys out.

The circuit can be found here:
http://www.muzique.com/schem/mosfet.htm

As the output is taken from the "Drain" of the Mosfet isn't this output signal Polarity reversed ("Phase Inverted") when compared to the input signal?
Doesn't it form an "Inverted" buffer?

Is there any reason for taking the output from the "Drain" instead of from the "Source"?
If the output is taken from the Source of the Mosfet it seems to me it would be "Non-Inverted" so would respect the same Polarity that is presented at the input?
Any reason for this, or am I'm missing something here?

Would the below example of the Non-Inverting work?

Thank you so much for all your help

 

[moamps]

The answers to your questions are in the same article next to the other schematic.

 

[Khron]

Well, the name of the circuit is "booster", not "buffer", so assuming that it's supposed to be unity-gain is... incorrect.

Taking output from the drain means you're using the amplified signal. If you took it from the source, the gain control would have no effect anymore.

I may be wrong, but absolute phase has rarely (if ever) been an issue in the world of electric guitar. Perhaps only when you start mixing together two or more parallel chains of effects and/or amplifiers and whatnot.

If you're looking for a buffer circuit, then look for that. Why use a booster circuit for another purpose, if you don't need to / if you have other (arguably better) choices?

https://sound-au.com/articles/fet-applications.htm#s8

 

[Whoops]

The answers to your questions are in the same article next to the other schematic.

No they aren't, at least not all my questions...

 

[Whoops]

Well, the name of the circuit is "booster", not "buffer", so assuming that it's supposed to be unity-gain is... incorrect.

I'm studying this circuit to check if it could apply to a project I'm doing, unity gain for my purposes it's better but doesn't need to be.

Taking output from the drain means you're using the amplified signal. If you took it from the source, the gain control would have no effect anymore.

I may be wrong, but absolute phase has rarely (if ever) been an issue in the world of electric guitar. Perhaps only when you start mixing together two or more parallel chains of effects and/or amplifiers and whatnot.

Yes, the problem is exactly when you parallel signals.
So for my usage being polarity coherent from input to output is important.

Could you help me out and check the second schematic I posted,
would it work as a Buffer with non-inverting output that way?

Taking output from the drain means you're using the amplified signal. If you took it from the source, the gain control would have no effect anymore.

Thanks for explaining that,
Besides the "Drain" signal being amplified, is there any technical benefit of using it's output instead of from the "Source"?

Thank you so much

 

[Gus]

Not enough information in the posts to help you.

The easy way if you need a buffer or gain and a higher input resistance and want to run at 9VDC is to use a good rail to rail opamp in noinverting.

If you want to use transistors you could use a JFET (IMO stay away from that MOSFET it is easy to break it) set up as a low gain inverting drain out stage into another device JFET or BJT set up as a low gain inverting collector out stage.
I posted low gain because the overall gain is multiplied.

If you need a buffer with out any voltage gain you can use a follower made from a BJT or JFET or JFET BJT pair OR other transistor configurations

If you post what you want you might get a good answer(s)

 

[Whoops]

Not enough information in the posts to help you.

If you post what you want you might get a good answer(s)

Don't really know what you mean by that,
I made some clear questions, you can help and answer them or not, it's up to you.

 

[Khron]

https://www.electronics-notes.com/a...nsistor-common-collector-emitter-follower.php
https://www.electronics-notes.com/a...stor/common-drain-source-follower-circuit.php

 

[L´Andratté]

Are you insisting on MOSFET?
The obvious point being a Fet input opamp like 2134 is hard to beat and if you need discrete the
circuits below are more workable (the are from AMZ too, so hopefully I´m not embarrasing you,
since you might already have decided against them (; )

If you want to use transistors you could use a JFET (IMO stay away from that MOSFET it is easy to break it)

JFet buffer
JFet buffer/splitter
The classic: AMZ Minibooster

 

[Newmarket]

The easy way if you need a buffer or gain and a higher input resistance and want to run at 9VDC is to use a good rail to rail opamp in noinverting.

But there's no indication that the OP requires rail to rail operation.
The best / preferred op amps for audio applications do not coincide with rail to rail types.
Apart from that - yes - basically if you want a unity gain non-inverting buffer then don't start with an inverting booster.
Mind you - I'm also 'opposed' to people (these days - Jaco P gets a bye due to the times) defretting bass necks to get a fretless so maybe that's just the way I think about stuff

 

[Whoops]

So here's the final circuit of this Buffer,
It's a non-inverted, unit gain buffer, and Very Hi-Z to Low Z converter.
Very usefull and works pretty well

 

[midwayfair]

As the output is taken from the "Drain" of the Mosfet isn't this output signal Polarity reversed ("Phase Inverted") when compared to the input signal? Doesn't it form an "Inverted" buffer?

From the article:
"The signal gain is essentially unity from both outputs with the switch open. Output 1 is phase inverted and output 2 is non-inverting."

Is there any reason for taking the output from the "Drain" instead of from the "Source"?

From the article:
"Depending on the device used, maximum gain should be about 35dB and minimum ~3 dB."
"When R6 is turned up, the switch closes and the circuit functions as normal and provides a boosted signal via Out 1. Out 2 should not be used when the switch is closed since it will not provide a full range signal."

If the output is taken from the Source of the Mosfet it seems to me it would be "Non-Inverted" so would respect the same Polarity that is presented at the input?

Answered in one of the quotes above.

Would the below example of the Non-Inverting work?

Your second schematic is output 2 of the second schematic in the AMZ article.

I know you've already resolved this with the last schematic you posted, but I don't think you should have been so dismissive when someone recommended [re]reading the article. Jack's site has been up for a very long time and he tends to be very thorough.

 

[Whoops]

https://www.electronics-notes.com/a...nsistor-common-collector-emitter-follower.php
https://www.electronics-notes.com/a...stor/common-drain-source-follower-circuit.php

Thank you so much Khron,
those articles were definitely good reads