Bill and Will's Synth
Larry Hendry JLH-822
Dual Channel Octave / Semitone Voltage Switch
Construction

December 2010 -

This page is one of twins.  To get to the other, for the JLH-831, click here.

A few days before Christmas, a box arrived from Gino Wong with several PCBs, some home-cooked, and, among the box's contents, two remarkable bits of history.  There, in their original envelopes, were the PCBs, panels, matched transistors, and notes for the JLH-822 and JLH-831 from Larry Hendry. 

"Choose the one you want and send the other back," Gino had said.  Well, we decided to build them first so he'd get back a built module.  Seemed like the least we could do to return his kindness.

You can't get the PCBs for this - they were sold out in 2002. Larry did offer plans for building the 822 on MOTM protoboard (below) - so, you could build one that way.

Even though you are very, very unlikely to build one, we've made this page (in the same style we always do) out of respect for Larry's memory - along with its parts list and all. We never had the privilege of knowing him; it's amazing to have the honor to build these two of his inventions... we already have a couple of the pedal interfaces he was instrumental in designing - the MOTM-850 (part of the Synthesis Technology lexicon, but no longer available there) -  and the last half-dozen of their PCBs we bought from Paul.  We'll get to those someday.

So here's our build of this historic module and by way of this page and the one for the 831, we raise our glasses to Larry - "Thanks, Man. This one's for you."

Table of Contents

Here's a table of contents that we hope will make this page easier to traverse:

Background - presents an explanation and Larry's initial description of the effect

Parts - presents a Bill of Materials and notes about it

Panel - presents the original "Stooge Panels" panel design

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

Construction Phase 2 - Trimmers - OK, this is where we've left off for now

Set up / Testing

Background

Larry wrote about the module on his site:

"The 822 is a 2-IN, 2-OUT voltage shifter that provides 3 octaves up or down of shift and interval shifting in semitones (all tunable). If you want to shift 2 oscillators, one up an octave and one up an octave and a fifth, you are only a flick of a switch away. The 822 is also useful for transposing on the fly."

schematic diagram - for Larry's .pdf version click here

overlay

PCB

PCB front

PCB back

An envelope of matched resistors came with the PCB.

And Larry's modification notes:

The protoboard version - looks quite do-able, really:

Parts

Will and I have developed a parts-list / bill-of-materials in the form of an XL spreadsheet. Granted, it's unlikely anyone will need it, but here it is. As of today, 23 December, 2010, it's complete.

Corrections to BOM:

None yet -

Notes:

None yet -

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

Panel

We used the original "Stooge Panel" that came from Larry to Gino.  Gino had drilled out the holes.

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.

ICs - Misc Stuff insulate Ferrite beads

Construction Phase 2

All the stuff in Phase 2 gets soldered using "No-Clean" Solder and the PCB doesn't get washed off from here on.

Set up / Testing

Use Notes