Resonant Lopass Gate PCB's (New Batch 4/29/12)

BananaPlug · Posted: Tue Sep 23, 2008 6:44 pm Post subject:

If the double happens will the height of the board and position of the pots allow for fitting it into a Frac Rack? The space between the rails is 4.25".

Also, you might be able to run traces on the PCB so that people can choose which board mounted pot does what by soldering in jumpers. I think that was done on the 281 boards.

Thanks

mark_a · Joined: Sep 22, 2008 Posts: 2 Location: us

hi, if another run happens or if there are any left over i'd like 2 boards please.

djthomaswhite · Joined: Nov 22, 2007 Posts: 140 Location: Orange, CA

Okay,

After much though, these will stay single boards... I know this may be sad for some, but it is what I agreed upon with Don. The cost for a larger board (based on total inches) went up as well. Hey, it's a lot of FR-4 more than these small boards. The circuit and schematics are freely available if you'd like to make your own double or quadruple boards. I can post the Express PCB file if anyone is interested in that. I wouldn't feel right going out of the boundaries Don agreed to. You have to understand, this man, a true legendary designer, gave me permission to make the run. Honor is not an option, but rather a necessity for this type of support of our small DIY community. So I will do my best to try and get the price of the boards as low as possible to make sure you can buy what you need for a good price.

BUT the good news is that I am trying to modify the circuit to use a TL074 with two separate mixer input stages so you can have this module have 3 inputs for audio AND 3 inputs for CV. Pots are optional and completely up to you.

With the addition of the mixer sections and resonance, this single section module becomes a fully featured filter (without 1V/Oct tracking though). I wish there was a way to make every request possible, but I will stick with my initial vision in producing the run. Thanks to everyone for your support!

More tomorrow. I should have been asleep 2 hours ago.

Thomas

PS. Can someone provide a trigger/gate extractor circuit to me so I can try and whip up a guitar pedal for my buddy. With one of these and a simple trigger you have powerful filtering at your hands.

numbertalk · Posted: Wed Sep 24, 2008 5:14 am Post subject:

So is there any way to at least make a larger run to accommodate all the extra interest? I personally would be willing to pay in advance for 4 boards if it helps. Please? Smile

BananaPlug · Posted: Wed Sep 24, 2008 5:36 am Post subject:

loss1234 · Posted: Wed Sep 24, 2008 7:22 am Post subject:

YES

how many of us can get in on this?

i would be so sad to miss out on this. i totally agree with you honoring DON's agreement

thanks

/mr · Posted: Wed Sep 24, 2008 9:07 am Post subject:

I cancel my previous interest in 4 lopass gates.
Since they are quite small I'd rather build a quad on veroboard in the future than putting 4 single PCBs behind a panel.

Don't get me wrong, I support to 100% your agreement with Don (which I didn't know of before) - and it's a great project you're making! Fabulously popular as well! Smile

numbertalk · Posted: Wed Sep 24, 2008 1:28 pm Post subject:

So since you haven't sent these off for production yet can you increase the run to accommodate the large response? Still would love 4 boards and will pay in advance for them if it helps. Thanks!

keithwin · Joined: Jul 20, 2007 Posts: 83 Location: uk

2 for me please!

djthomaswhite · Joined: Nov 22, 2007 Posts: 140 Location: Orange, CA

Whew, another late one. But it is all in good effort to make a solid PCB so it is worth it.

Attached are the latest build docs including the Revision 1.7 files. There is a parts list, actual size PCB image, blown up color PCB image and the revised schematic since adding the second mixer section. I am sending off the PCB for proto production after a final check tomorrow. Looks good but I don't want to waste money on some stupid trace problem as you might imagine.

The part list has all the Mouser part numbers, with exception to the Vactrols which can be obtained from Allied Elec here in the states. My apologies to International folks as I am not familiar with part numbers in your area to get this moving. Maybe someone can put that together for Rapid or Farnell in the UK?

Off to bed. As you can see, things are moving along nicely. I may be upping the run. No solid news yet, but I am working on a large run once rather than a batch now, later and yet again after that. Too much mailing. Boards will likely be $10 as mentioned, but with shipping and handling included in the US.

Not sure how much extra International will cost, but I will try to make a discount since people are ordering up to 16 boards (still boggles my mind). I can't imagine more than a few extra bucks. I'll ship express but at your cost. Otherwise shipping will be the normal first class, "up to 14-days to get to your country" type of thing.

All docs will be in a zip file like the one below, but I will include everything I have in a final version.

Thanks gang, more to come!

Thomas Very Happy

Lopass Gate Revision 1.7.zip

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Lopass Gate Revision 1.7.zip

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chrissugar · Joined: Sep 23, 2008 Posts: 34 Location: ROMANIA

Hi Thomas

Have you read my post about the ERROR I posted on the previous page?
I registered to this forum to mention it and avoid some possible problems before PCB fabrication. Exclamation

chrissugar

Dave Kendall · Posted: Thu Sep 25, 2008 3:24 am Post subject:

FWIW, I'm pleased that they are single boards, as I plan to put one in a fixed architecture rack synth, as one of the filter options. Others will go in the modular.

great work, and thanks. Smile

cheers,
Dave

fonik · Posted: Thu Sep 25, 2008 3:26 am Post subject:

loss1234 · Posted: Thu Sep 25, 2008 3:43 am Post subject:

if shipping is included in the states..i would like THREE not 2. (if you do a big run.)

this is a popular board eh?

thanks

numbertalk · Posted: Thu Sep 25, 2008 6:38 am Post subject: Re: Another Late Night

chrissugar · Joined: Sep 23, 2008 Posts: 34 Location: ROMANIA

djthomaswhite · Joined: Nov 22, 2007 Posts: 140 Location: Orange, CA

while the schematic is different, it might be due to using angle vactrols instead of dual and here is the factor of the ic switch being replaced with a hardware one to consider. I will not send boards for proto until this is figures out

Matthias can you help me troubleshoot this? I can check on my end and we can compare findings. Anyone else that knows more about design can help too and it would be much appreciated.

I will say that my versions seems to be 100% functional in all modes. Not sure what actual difference will be made in the end but it is worth checking out. As stated bfore what is worth doing is worth doing right!

Thomas

Serenadi · Joined: Jul 03, 2007 Posts: 89 Location: Germany

djthomaswhite · Joined: Nov 22, 2007 Posts: 140 Location: Orange, CA

Seranadi,

I think you are looking in the wrong place my friend for the ChrisSugar question. Pins 6 and 7 are not the Output Op-Amp stage. Changing the resistor connection there changes the range of the offset pot, which matches your description of the audible effect you end up with. My "Deep Switch" mod on the board connects these two pins with a switch and a 47K resistor to allow for purposely deeper offset settings.

Thanks for the input on the pin 12 resistor though. I will try that in my built design to see if it does the same thing on my PCB. If so, I will add it to the design and docs. Thanks!

numbernone · Joined: Aug 16, 2006 Posts: 477 Location: new york city

Wow I was just about to send of my own layout to PCBcart last week before I left the country, and return to find this giant thread!!

Still gonna roll my own as they are doubles on a board smaller than these singles, but do await the final results of these error fix mods or whathave yous. Man there is gonna be a whole lot of twanging going on soon for lots of folks.

Cant wait to see what peoples are able to clone next, MARF?? SOU??? I hafta revisit my 291 (Stites style), and get the BW working. Its a GREAT filter.

djthomaswhite · Joined: Nov 22, 2007 Posts: 140 Location: Orange, CA

Hey Guys,

I have all three schematics in front of me. OG Buchla, Fonik (grenader), and my version. The output of the 4.7n cap connected to the Vactrol goes to the switch (S5 on mine, W5 S-8 on Fonik's and an "X" on Bucha's schematic). This connects via the switch to S6 on mine, W6 S-9 on Foniks, and the other side of the "X" on Buchla's. This continues to the final op-amp stage. On the Buchla/Verbos schematic the connection goes to the juntion of the 10K resistor and Pin 8 of the TL084. On mine and Fonik's design the connection goes to the junction of the 10K and Pin 9 instead.

I will change this around with my version tonight to check the change. If it is prudent (as I am sure it is) I will adjust the PCB. Thanks for catching this Chris Sugar! I will also see about adding the 100K resistor to ground between pin 12 of the TL084 and ground to eliminate pops when switching modes.

Thanks for the help Gents. This is a fine example of why electro-music is the best place for us DIY guys to get our strengths together in the name of correct design. Imagine... I send one to Don and he goes "Well, it's great and all, but you F'd up on the last section of the circuit..." Shocked

Thomas

Serenadi · Joined: Jul 03, 2007 Posts: 89 Location: Germany

fonik · Posted: Thu Sep 25, 2008 11:44 am Post subject:

thank you, serenadi, for this great info. just in time! Very Happy

chrissugar · Joined: Sep 23, 2008 Posts: 34 Location: ROMANIA

chrissugar · Joined: Sep 23, 2008 Posts: 34 Location: ROMANIA