SBG-PID

[scs]

You have mistakes. I have not checked everything, I do not have time.

[wallker]

The resistors R43 and R51 are selected according to the meter

That's why I put a trimmer there, as I wrote in a post.

Only the two resistors R43 and R51 are changed with trimmer, rest is original.

There was indeed error at c11 and c12, it's just hard to read your sch. (red is how I would done it, black circle is how you done it)
Anyway tnx you for noticing, I've changed that now.
I'm looking forward to eliminate all the errors that exists on schematic.
Version with corrected caps: SBG-PID.pdf

[6666]

Walker what did you draw that in, it was fast.

[wallker]

Hi 6666,
I drew it in altium designer.

[6666]

Hi 6666,
I drew it in altium designer.

[bernte_one]

lf357 is obsolet, why did all engineers here continue drawing design with lf357
i got a handful of fake lf357 from ali, just for testing - but they are crap

[scs]

And the darlington transistor is old.. .Aber arbeitet sehr gut!

[Andi68]

http://www.allxref.com/search.htm?part=LF357

http://e2e.ti.com/support/amplifiers/f/14/t/84056#

[ivconic]

Always hate to see such awkward way of drawing schematics.
Purposely messed up to the level of being completely confusing.
Also kind a looking more "profound" than actually it is.
Now, once you put it on "paper" on right way; everything evolves nicely.
...
As for the design; it's alright. Simple enough and yet offering some features which other simple pi designs are lacking.
It is a step forward comparing to other simple PI designs available on this forum. Not just "another pi...".
I hate to see the analog meter scale there.
Was it so hard that voltage to fed to thrs. input of cmos vco and get two-tone behavior?
7555s are cheap, why not using even two vco's? And get two nice trimmed and pleasant tones.
Just an idea.
Timings... 4538, also hate to see them too. Atmega can replace them with no sweat at all.
Etc etc...
Things can be lifted on much higher lever here.
It is good starting point though.
I had enough "fun" time to redraw schematic as i like to see it.

[6666]

Thanks Ivconic , very quick drawing

[6666]

lf357 is obsolet, why did all engineers here continue drawing design with lf357
i got a handful of fake lf357 from ali, just for testing - but they are crap

I got a bunch of fakes to

[ivconic]

Of course; looking at such terrifically awkward drawings: you can generate only more mistakes in redraw.
So i spotted one i made at ps part.
Here is corrected:

[waltr]

Always hate to see such awkward way of drawing schematics.
Purposely messed up to the level of being completely confusing.
Also kind a looking more "profound" than actually it is.
Now, once you put it on "paper" on right way; everything evolves nicely.
...
As for the design; it's alright. Simple enough and yet offering some features which other simple pi designs are lacking.
It is a step forward comparing to other simple PI designs available on this forum. Not just "another pi...".
I hate to see the analog meter scale there.
Was it so hard that voltage to fed to thrs. input of cmos vco and get two-tone behavior?
7555s are cheap, why not using even two vco's? And get two nice trimmed and pleasant tones.
Just an idea.
Timings... 4538, also hate to see them too. Atmega can replace them with no sweat at all.
Etc etc...
Things can be lifted on much higher lever here.
It is good starting point though.
I had enough "fun" time to redraw schematic as i like to see it.
[ATTACH]46083[/ATTACH]

Much nicer and easier to follow drawing.

Yes, there is much of the design that could have been upgraded. Any small processor easily does all the timing and allows easy experimentation and even several modes in the field.

VCO output is a must if having low/high conductor discrimination. There can be a lot of audio information this way.
Lots of simple methods for VCO.
A meter is handy to check strength of signal, target size/depth. I added a meter to my HH2 and is handy at times.

[ivconic]

Much nicer and easier to follow drawing.

Yes, there is much of the design that could have been upgraded. Any small processor easily does all the timing and allows easy experimentation and even several modes in the field.

VCO output is a must if having low/high conductor discrimination. There can be a lot of audio information this way.
Lots of simple methods for VCO.
A meter is handy to check strength of signal, target size/depth. I added a meter to my HH2 and is handy at times.

Use of Atmega and LCD will allow tossing 40-60% of present schematic out.
But first it would be good to make it as it is and see the behavior.
Later on, step by step to replace some parts with code in Atmega.
I might do that when i nick some spare time. Will see.

[scs]

I noticed error a transistor VT9 is connected back. Please for excuse.