Bill and Will's Synth
MOTM 800 Two Dot Oh Construction
"Envelope Generator"
(yup - it includes the Tellun 800 Daughter Board)


August 2007 -

OK - why a second MOTM800 page?  'Cause we can.  No - really - 'cause we're building our fifth 800 this way - and it's a little different when you're working from a Synth Tech 2.0 thing rather than a full-blown "kit."  So if you feel the need, cross reference this with the KitPage here.

We're going to dispense with all the explanation stuff and go right into building the thing.  But on that Kit Page, there is cool info about the EG's behavior and stuff.

Table of Contents

This page has become really long, so here's a table of contents that we hope will make it easier to traverse:

Parts - presents a Bill of Materials and notes about it

Panel - presents the alteration to the Synth Tech panel

Construction Phase 1 - Resistors, Capacitors, IC Sockets, Power Parts, MTA headers

Construction Phase 2 - Trimmers, Panel connections

Set up / Testing

Use notes


Will and I have developed a parts-list / bill-of-materials in the form of an XL spreadsheet based on the parts list in the 420 User Guide.

Click here to download the XL spreadsheet (apx. 350K).

Click here to download the .pdf Synthesis Technology parts section of the User's Guide.

Click here to go to our Bill of Materials Page.


Because we're including the Tellun 800-DB, we needed to modify the Synth Tech panel to include two LEDs - one green - one yellow - which will serve as indicators for the action of the clipper and the progress of the envelope.  So just like we did before, we drilled the two LED holes in the panel we got from Paul.  For details, go to the MOTM-800 Page, here.

all done - looks just fine

Construction - DB-800

We built this back in Aught 7 when we built the other four 800ds. Click here.

Construction Phase 1

All the stuff in Phase 1 gets soldered using "Organic" Solder.  At every break in the action, we wash the board off to get rid of the flux.

we got some critical parts from Paul

PCB front

PCB back

Cut Traces

We decided to cut these traces on the bottom of the Main PCB like we did last time to accommodate the DB.


we're using all 1% (blue) resistors 'cause that's what we have on hand. If you are used the BOM to get your parts, they'll all be 5% and be tan-colored.

As usual with us, whereas we are vigilant about orienting all the resistors, caps, etc. consistently so their values can be read easily (in case we need to trouble-shoot them later), we oriented the resistors with the "Tolerance" stripe on the left (relative to the text on the pcb).  You might want to do it the opposite way.  (For the table of resistor value markings click here.)


Power Header, Ferrite Beads, IC Plugs, Semiconductors

We decided to use Jacks for our ICs - optional.

Construction Phase 2



We fit the pots into the panel. Looks to us like the 3 Coax and one twisted triple can be around 4-1/2in long:

MT Plugs

Here's how the wires go into the MTA plugs

The jumper and wires on the back of the PCB

The gate wires

Trigger, Coax, ICs


Mounting the PCB

Connecting the Jacks

Daughter Board Mounting

the daughter board mounted



Set up / Testing

Use Notes


Bill and Will's Synth Main Page
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The fine Print:
Use this site at your own risk.
We are self-proclaimed idiots and any use of this site and any materials presented herein should be taken with a grain of Kosher salt. If the info is useful - more's the better.  Bill and Will

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