VC Delay pcb redesign - SAD1024

[The Peasant]

I am building a couple of T.H. VC Analog Delays in my current synth project, from 3 original parts kits that I purchased some time ago. I wanted to keep at least one of my SAD4096 ICs as a spare, and so I decided to redesign the pcb board layout to use the SAD1024 IC for one of the delays. As the 4096 is basically unobtainium these days, I thought that others who had access to a SAD1024 and wanted to build this delay could use this.

Take care,
Doug

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[philpeery]

Really nice job Doug! This is one that I've been meaning to tackle myself for a while, glad you got to it! I have a couple of quick questions - did you generate a parts layout, or is it essentially the same as TH's? Also, did you replace the unobtainium 4739 opamp chips with a modern part? I think there are 3 in this project. As I recall, that chip has an unusual pinout that few other opamps share.

Great work! I'm going to go over the layout and try to get at least one built over the holidays!

Regards,
Phil

[The Peasant]

Hi Phil,

Glad that you can make use of this. To answer your questions - other than the delay chip and a couple of parts immediately around it the layout is identical. I can do a quick layout diagram for the differences in the next while if you like. I did add room for ferrite beads on the power inputs and moved the electolytics there over a bit. I also beefed up the traces a lot.

It does use the 4739 op amps, but it should be fairly easy to modify the board for something more standard. If I was to do it again I would change the trimpot pads to something smaller as well.

Please note that I have not yet actually tested this design. I have an etched and populated board ready to go into my latest project, so this will happen in the next couple of months. Also note that there are two different ways to utilise the dual delay lines in a SAD1024, this design uses the parallel method for a higher quality, shorter delay.

I am also planning on adding VC regeneration to this module using a MFOS VCA pcb.

Take care,
Doug

[philpeery]

[richardc64]

Welcome, "Peasant."

I consider myself one of your disciples, and emailed you once to tell you so and exchange ideas on synthsized drums. Is your monster project still on hold?

Glad to see you here.

[StephenGiles]

I built this wonderful flanger (aren't they all!!) back when "Device" was still being published - back in the days when we had postal deliveries by 8am in the UK!! The original articles are still up at Mark Hammer's site.

I used the Eventide bounce with Deluxe Electric Mistress clock/LFO which worked well together. I must fire it up again, I remember that the regeneration sounds were superb.

No - I'm talking rubbish, I'm referring to Craig Anterton's VC Flanger - una pava distinta de pescados

[The Peasant]

[The Peasant]

[The Peasant]

OK, I can now confirm that this pcb layout works with the SAD1024, and that the MFOS Dual VCA can be easily used for VC Regeneration. Just connect the VCA in place of the potentiometer and use the VCA panel offset control to set the regeneration amount.

I have also made some modifications to the MFOS VCA, see here for the details: http://electro-music.com/forum/topic-38568.html

Below is a picture of the pcbs all wired up and working. I added some voltage regulators to the board as well.

Take care,
Doug

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[aerogramma]

all the ebst from here Peasant

your designs are very inspiring... I have just completed salvaging enough material for a VDF Ring mod so it will be next!



aero