5-channel Attenuverting Mixer 2nd run

fonik · Posted: Wed Oct 01, 2008 1:14 am Post subject:

nice shot!

these are precision ceramic disc caps? zero tolerance? i don't think you will experience any problems. leave them, they're looking quite good.

these are just filter caps to keep the voltage rails clean, so as said before, it does not matter IMO.

LektroiD · Posted: Wed Oct 01, 2008 3:05 am Post subject:

LektroiD · Posted: Wed Oct 01, 2008 6:26 am Post subject:

Since this is my first module, I have a couple of questions regarding connectivity...

The power source connector, there appears to be two, is this for choice, or do both need to be there? Is there a standard for modules? And what are the part numbers?

Also, I have soldered pin connectors for the panel components, is this the standard procedure? I need to know what sockets I can buy to connect to the panel components to them?

I have included another picture:

AttenvertingPCB2.jpg

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fonik · Posted: Wed Oct 01, 2008 6:50 am Post subject:

Kent · Posted: Sun Nov 09, 2008 5:03 am Post subject: 2 PCBs for Paris, France

I'd like 2 of them please.

Thanks.

fonik · Posted: Sun Nov 09, 2008 7:05 am Post subject:

great. check your PMs, kent. Very Happy

Appliancide* · Posted: Sun Nov 09, 2008 12:39 pm Post subject:

One of my IC sockets might be questionable. Can you tell me what voltages to look for before seating the ICs? The one I'm worried about is IC3.

Also is the one connection that is shown with a line on the pcb just a wire or is there something specific that I should use?

Sorry if this has all been covered, but this will be my first completed module so I want to make sure it's right before I power it up.

Thanks,
Paul

fonik · Posted: Sun Nov 09, 2008 2:16 pm Post subject:

fonik · Posted: Mon Nov 17, 2008 4:33 pm Post subject:

modification advice Exclamation

hold on! tonight i got aware that the AC/DC selector does not work as it should (no, i am not about the latest heavy metal CD release here Wink

). i found that one resistor is missing. embarrassing and awkward enough.

anyways, one would have to add a 100k resistor from the junction of R28 and C13 to ground.
you could do this on the front panel (i.e. solder the resistor from switch SW1 pin1 to a ground connection of one of the sockets) or even on the board.

this applies to both the old and the new board. i will amend the documentation ASAP.

fonik · Posted: Tue Nov 18, 2008 2:48 am Post subject:

documentation updated:
rev2 doc

panele · Joined: Apr 13, 2008 Posts: 19 Location: mainz, germany

i`have built 2 of the mixers and have a little problem on both.
i`m getting channel 1 & 3 adjusted and they work fine. i don`t get
channel 2 & 4 correctly trimmed. i`ve changed trimmers, pots, tried
different ics (tl072cn, tl072cp) but nothing seems to help.
any ideas?

RF · Posted: Thu Nov 27, 2008 10:02 am Post subject:

Matthias - Do you still have any of these boards?
I'd like a couple more.

This has been a REALLY useful module!

bruce

panele · Joined: Apr 13, 2008 Posts: 19 Location: mainz, germany

fixed the problem, wrong pot-wiring.
thanks

fonik · Posted: Fri Nov 28, 2008 11:50 am Post subject:

BTW

SOLD OUT

numbertalk · Posted: Mon Dec 01, 2008 10:12 am Post subject:

Hi Matthias,

I would like to use 1 or more of the inputs on one of these boards to increase the p-p voltage of waveforms from a couple of my VCOs. If I wanted to have 1 input double (from 5Vp-p to ~10Vp-p, for example), could I simply keep the 50K pot and for input 1 change R4 to 100K? If Ialso wanted to have another input triple (from 3Vp-p to ~10Vp-p), could I again keep the 50K pot and change R7 to 150K (or 165K + 1.5K in series to get closer) for input 2? Would the 50K trimpots for each input complicate this? Also would any other resistor values need to change?

Thanks!

fonik · Posted: Mon Dec 01, 2008 2:35 pm Post subject:

numbertalk · Posted: Mon Dec 01, 2008 6:09 pm Post subject:

thanks for the info.

what i'm describing would be possible by changing resistor values for this cgs circuit, though, right?

http://www.cgs.synth.net/modules/cgs04_mix.html

thanks again.

fonik · Posted: Tue Dec 02, 2008 2:22 am Post subject:

numbertalk · Posted: Tue Dec 02, 2008 7:31 am Post subject:

Funky40 · Posted: Tue Dec 09, 2008 1:02 am Post subject:

Fonik, why do you choosed 10NF instead of 100 NF as they take all the time ?
Can i take 100N ?

fonik · Posted: Tue Dec 09, 2008 2:03 am Post subject:

Funky40 · Posted: Tue Dec 09, 2008 4:31 am Post subject:

ok, thanks

rjd2 · Joined: Sep 02, 2007 Posts: 236 Location: philly

so i finally built one of these, and im having a problem. when i sweep thru the trim pot,i get no voltage change at the output jack of channel 1.

i've checked all 4 IC's, and im getting +/-15V at pins 8 and 4, respectively. power is definitely wired properly.

ive added the 100k R for the dc/ac switch at C13. ( i just wired a 2-pole switch across the 2 pads of "SW 1").

im not using switched jacks. im using the same center detent 50k alpha pots that were referenced.

maybe can someone clarify in the docs, is your black wire on the pot wiring ground? i cant tell for sure from the orientation, since it looks like the order of the pot pads is reversed on the bottom of the board from the top.

thanks for the help.

ericcoleridge · Joined: Jan 16, 2007 Posts: 889 Location: NYC

numbertalk · Posted: Sun Jan 25, 2009 8:38 pm Post subject: