Bill and Will's Synth
Tellun 861 "Dunsel" Construction
Page 1 - Beginning and End

November 2009 -

In February of 2007, in the process of perusing Scott Juskiw's site, foraging for mods we'd want to include when building our Synth Tech MOTM kits, we came across the Dunsel Utility Module. But we didn't tackle it until November of 2009.

Scott's TLN-861 Dunsel web page is here. You can download a .pdf copy of the  1.0.1 User Guide we used by clicking here (apx 143K). The module has no PCB specifically designed for it. Rather, it uses some of the Multi-Use Universal Buffer (MUUB) PCBs designed by Richard Brewster, Larry Hendry, and Scott Juskiw and available through Scott.

The build described in the Users Guide above, uses four MUUB4 and three MUUB2 circuit boards and is what we used to do our build.  As we were building the Dunsel, Scott posted an alternative build that he considers preferable - and we completely see why.

That build uses two MUUB3s and one MUUB2 and you may want to check that out on his web page. The advantage is that there is only one layer of boards rather than three and so the need for inter-board connections is minimized and the jack are more easily made.  The disadvantage is that, heretofore, there's no clear documentation and diagrams for the build.  Nonetheless, if you're very confident, you may want to tackle it that way.

Will and I found an omission in the Guide - a jumper - required on PCBs 1A and 2A at JA6.  This jumper should be listed as "jumper | JA6" in the tables of components in sections "5.1 Building Board 1A (MUUB4)" and "5.2 Building Board 1 B (MUUB4)." of the Guide.  Our diagrams include this jumper and our build also shows it - although we discovered it in process.

It's perhaps worth noting that whereas the Dunsel's complexity was intimidating, the build really isn't all that difficult.  It was time-consuming... but mostly because of our uncertainty and need to think everything through.  With these pages in hand, it would have been much easier and so we hope it will be for those who come after us.

Table of Contents

This documentation has become so long that we've broken it into three separate pages and sections within them.  Here's a table of contents that we hope will make it easier to traverse them:

Beginning and End (this Page)

Background - presents an explanation and Scott Juskiw's initial description of the module with a photo

Parts - presents a Bill of Materials and notes about it

Panel - presents the MOTM format panel

Mounting Brackets - our use of two "Stooge" 3-pot brackets

Snack

Construction Done

Set up / Testing

Use notes

MUUB Construction Page

Construction PCB 1A&B - MUUB4

Construction PCB 2A&B - MUUB4

Construction PCB 3A&B - MUUB2

Construction PCB 4 - MUUB2

Connection Wiring

Connections Page

PCB Connections - wiring the PCBs together

Panel Wiring - connecting the PCBs to the panel

Background

Scott writes:

The TLN-861 Dunsel is a utility module that generates several commonly used signals from an input voltage. When patching my synth, I find I constantly require unity gain inverters, adders, subtractors, half/full wave recitifiers, and level shifters. While it's possible to generate these signals using MOTM-830, Oakley WaveFolder, or Oakley Multimix modules, that's not often the best use of those resources. Enter Captain Dunsel to the rescue.

The Dunsel features two channels (A & B) with the following independent outputs:

• INV A/B: unity gain inversion of input.
• NEG A/B: negative portion of input.
• POS A/B: positive portion of input (half wave rectification).
• FWR A/B: full wave rectified version of input.
• A/B - 5: level shifted version of input (-5V level shift).
• A/B + 5: level shifted version of input (+5V level shift).

The Dunsel also has the following combined outputs:

• A + B: sum of A and B inputs.
• A - B: difference of A and B inputs.

The TLN-861 Dunsel can be built using MUUB daughterboards.

Total current draw for TLN-861 is 38 mA @+15V and 38 mA @-15V.

Schematics

Here's Scott's Schematics (click on the images to see a high-rez version):

Parts

Will and I have developed a parts-list / bill-of-materials in the form of an XL spreadsheet (as usual).

It's pretty complete now - we are relatively confident in our specifications.

Click here to download our XL spreadsheet Parts List

Panel

We got ours at Bridechamber.

Mounting Brackets

Scott urges assembling the pcb brackets and the panel first.  We figured out that two of the Bridechamber three-pot mounting brackets would do the trick like this:

We marked the brackets for drilling, drilled the holes, and thought we had done well.  It wasn't until later that we realized that with the PCBs at this distance from the panel, we needed to increase the length of the PCB-to-Jack wires by 2-1/2 inches (foolish of us, yes) so we re-drilled the brackets so the PCBs are right close to the jacks.  But if you're doing it this way, please consider making the wires longer and keeping the PCBs away from the panel (assuming your cabinets will allow the depth) because it'll give you more room to maneuver as you're soldering up the jacks.

Construction / Connections

Go on to Page Two - MUUB Construction

Go to Page Three - Connections

And now, back to work.

Construction Done

Set up / Testing

Use Notes