Jakob`s noise gate schematic (here!)

I was searching noise gate and compressors schematic to take ideas for a cheap guitar noise gate design, and I found this pcb layout from Jakob. there was no schematic so I re-trace it.

the filter part is new to me and can be some mistakes there, and one pin of the tl072 is not conected, I believe that it is just a buffer. I forget to put the value of jfet it is a bf245 if I remmember well.

here is the layout.
http://groupdiy.twin-x.com/albums/userpics/10004/Gyraf_NoiseGate_Layout.PDF

and here is the schematic.
http://groupdiy.twin-x.com/albums/userpics/10131/normal_noisegate.jpg

I hope you can help me to find errors.

greetings
12afael

Could we have a bit larger image - it's a bit hard to read..

But it looks right at a glance..

:thumb:

Jakob E.

I'mconfused aout the no-output-connection opamp on the right side...

Keith

sorry here is the big schematic.
http://groupdiy.twin-x.com/albums/userpics/10131/noisegate.jpg
or here
http://groupdiy.twin-x.com/displayimage.php?pos=-1663

I'mconfused aout the no-output-connection opamp on the right side...

Click to expand...

it look like a simple op amp buffer but on the layout it is not conected.

oops, Layout error - yes, standard buffer, out and -in should be connected.

Filter is two standard state variable sections in series. You have tiny drawing
error in filter section: 470ohm resistor should be conencted to - input of
opamp with "nose-down" insead of output, in HF section. Same thing with
100k revlog in LF section.

cheerz
urosh

then the error is on the layout too. I re-check the filter section because I didn´t know it. the way how the 1k resistor is conected on the hi frec filter is ok? two caps values are missing on the schematic 22n on hte lo freq and 47n on the hi freq.

There could be some connection errors on the layout - the pcb has been drawn from a hand-laid-out original from the good old days - but the redrawn pcb has never been used (though the original handdrawn one has been used a lot, and is known working). I'll try to find the handdrawn version for reference.

Jakob E.

having seen people asking about diy-gates around here, including myself, I just want to say, please go on with this! :thumb:

Great you're doing this 12afael and big up to Jakob too!
:guinness: :sam:

if we have a good schematic is not hard to repair the layout, the hard work is already done.

Jakob , this noise gate need an external power supply? 22uF filter is not too big. :?

looks like its designed to take regulated/filtered bipolar 12v dc

thanks for putting in time on this rafael..... are you going to be doing a 'relayout' ??

are you going to be doing a 'relayout' ??

Click to expand...

You mean hard-bypass? It's already there, in the bypass switch..

Jakob E.

naw, just wondering if he planned on doing a new layout of the pcb.... sorry to confuse

it is to be fed +/- 12vdc though right?

1k from filter section is ok. I have a feeling there is some capacitor
missing somewhere around Hold pot in lower left corner. Or to be precise
that series conection of 47k and 2.2M pot needs to see some capacitance
in paralell to work. Dont know what is used as comparator but
I doubt it has enough input capacitance to work.

urosh

Jakob, would I be wasting my time redrawing 12afael's drawing? Might you find your original schematic of this? Has the FET been identified I wonder? Over and out!

FET is 90%sure a BF245A.

I've looked for the schemo for a long time, but haven't been able to find it yet.. :?

Jakob E.

I know the feeling Jakob! I have several piles of schemos in various places in our house and I usually have to go each one 3 times at least in order to find anything.

FET is 90%sure a BF245A.

Click to expand...

on the layout say BF245 B

1k from filter section is ok. I have a feeling there is some capacitor
missing somewhere around Hold pot in lower left corner. Or to be precise
that series conection of 47k and 2.2M pot needs to see some capacitance
in paralell to work. Dont know what is used as comparator but
I doubt it has enough input capacitance to work.

Click to expand...

your are right there is a 220n cap that I forgot to put .
I notice a resistor without value on the output of the threshold comparator(my error too) it is a 4,7K.

would I be wasting my time redrawing 12afael's drawing?

Click to expand...

I am going to fix all the modifications when I know clearly all of them. I have a tablet to draw so it will be by hand too. if you want to re draw the schematic in some electronic program, just wait to have a more corrected version.

thanks for putting in time on this rafael..... are you going to be doing a 'relayout' ??

Click to expand...

I don`t believe that I go to construct a noise gate in the near future , I have a pile of projects to finish and it is still not justified in my small homestudio. But if somebody can help me with the schematic in eagle I believe that I can do a layout guiding me by the design of Jakob. (layout is cool but draw the scheme is boring)

PostPosted: Tue Sep 26, 2006 3:45 pm Post subject:
I know the feeling Jakob! I have several piles of schemos in various places in our house and I usually have to go each one 3 times at least in order to find anything.

Click to expand...

me too. we need some like this.

here is the rev1 schematic I add some values and correct the filter part and the buffer for the led drivers.


http://groupdiy.twin-x.com/displayimage.php?pos=-1675
and here is the big schematic
http://groupdiy.twin-x.com/albums/userpics/10131/noisegate_rev1.gif

[quote author="12afael"]heavy metal is the law!!![/quote]
Sorry, seeing your quote in a noise gate thread I can't help being reminded of what others said when I was listening to that stuff... :wink:

Imagine a tape of the album below and then switching on the noise reduction... total silence will result... (as they said)




Enough OT, back to schematics.