Wednesday 27 December 2023

Triggered Controller

 This is one of a number of custom modules that Moog made for the University of New York CEMS system in 1969.  Also known as the "one step sequencer".

The module generates three controllable output voltages actuated by either push buttons or V-trigger inputs.

My design is derived from pictures of an original module on the website. The Moog PCB for this specific module has been modified to provide negative output voltages; the assumption being that as originally designed it generated positive voltages.

In my implemention, the output range for each potentiometer can be configured using jumpers.

PCBs are available now , panels are currently made to order.

Sunday 3 September 2023

Rotary Switch Availability

Many of my "moog" modules need Alpha (Taiwan) SR2511 series rotary switches. My preferred supplier for these has been even though they have a minimum order value. However they now appear to be out of stock with long lead times.
Mouser does stock compatible switches with round shafts. Round shafts are fine, just don't use "D shaft" switches with these modules or the knob won't align with the panel graphics. However all of the Mouser stock appears to be the "19R" shaft height variant, which will leave the knob very high above the panel which looks ugly.

I have located the following alternate suppliers, I have no connection to either of these:
- in the EU: has some stock of the Alpha parts (e.g. part number 12679 for 4P3W). They won't ship outside the EU, and note that the UK is no longer in the EU!
- in the UK: has compatible switches, part numbers 483323 for 4P3W (904C), 483320 for 1P12W (901A), 483321 for 2P6W (901B). These switches are "open" and don't have dust covers. If you only want one or two, it may be cheaper to purchase via their ebay shop.
 - elsewhere: if ordering PCBs from me, please ask about any switches you need. I can supply those from Switch Electronics "at cost", saving you any additional shipping costs.




Saturday 19 August 2023

901B PCB Restock

 I've restocked with PCBs for the 901B Oscillator module, and for the Universal Daughter Board (UDB) used in the 904C PCB set.



1630d BOM errors

 It's come to my attention that there are a couple of errors in the BOM for the 1630d Frequency Shifter,  however the schematic values are correct.

R17 and R22 are 33K

R16 and R21 are 200K

In combination with the 100k CV input resistors, these values will scale a 10V CV range (+/- 5V ) onto the 3V3 range that the Teensy ADC uses.

1630d Build Doc version 1-3 corrects this error.

Tuesday 21 March 2023

3D Printed Knobs

 I've been experimenting with some 3D printed knobs and switch caps for my "Moog" modules.

First, we have switch caps for the 1125 sample-hold module. These a mini version of the Moog slide switch caps on the original, printed in white ABS.

Then, a basic "chicken head" knob to match those on Behringer modules. They are designed to be a tight push fit onto a T18 shaft - the shaft will cut its own alignment grooves into the knob when the knob is first installed. These are plain black ABS so you will need to paint your own white line and any infill. 

The switch caps are currently free with a purchase of the 1125 panel, the knobs are GBP 1.00 each.

Friday 3 March 2023

1630d Frequency Shifter

 My latest module, the 1630d Frequency Shifter.

This could be considered a "cheat", as the module is a digital interpretation of the Moog/Bode 1630 Frequency Shifter module. For ease of construction and programming I have based this on a standard Teensy 4.0 processor module together with the Teensy Audio Board. A custom front panel PCB hosts these together with the controls and interface circuitry.

The original Moog module requires many careful adjustments, or close tolerance component selection, in order to operate successfully. I therefore thought that the digital approach was justifiable in this case.

Note that this is a "Frequency Shifter", not a "Pitch Shifter". 

There are some differences between the 1630d and the original Moog 1630:

  • The 1630d includes two audio inputs; the 1630 has only has one.
  • There is no dedicated “mix” output on the 1630d – the MIX output can be assigned to “OUT A” or “OUT B” (or neither)  using the “MIXTURE” control and associated push button.
  • The 1630d includes a “MIX CV” input that can control the content of the MIX output.
  • There is no “ZERO” position on the SCALE switch, as this is not required for the digital version. The switch position has been re-used to provide a 1V/octave calibration function (CAL) for the CV inputs.
  • The 1630d uses digital FIR Hilbert filters instead of the (analogue) "dome" filters used in the original. At low frequencies the digital filters are not as flat in their phase and frequency responses as the original analogue ones.
  • The software contains several user configurable options to tailor the module to individual taste.

The module can be build using only though-hole components. Some of the ICs have surface mount options instead of through-hole to ease component sourcing. You will need to be able program the Teensy module using the open source software.

PCBs are in stock, panels will be in stock soon.


Thursday 2 February 2023

Monday 23 January 2023

International Shipping

 UK Royal Mail is suffering the effects of a "cyber incident" that has affected all international shipping.

 I won't be able to ship any international orders until this is resolved.

Tuesday 10 January 2023

New "Moog" modules for 2023

Three new modules for 2023, see the "Moog eurorack modules" page for more details:

951 and 952 Keyboard Inferface modules.

These modules provide functionality that is present in Moog modular keyboards, and are primarily intended to provide easy performance adjustment of 901A/B oscillators. They can also be used with standard Behringer System 55 VCO modules.

Each module features:
-  “Scale” control: CV multiplier, from 0.94 to 1.06
-  “Range” control: adds or subtracts an offset to the CV ±150mV (approx 2 semitones)
-  Switchable exponential or LCR (“linear constant rate”) glide.

The 951 is an 8HP single channel module. The 952 is dual channel module, also in 8HP.




1125 Sample-Hold Controller

The Fitzgreyve 1125 is a 16HP Eurorack implementation of the Moog 1125 “Sample-Hold Controller “ accessory.

The original Moog design has been used, but with the following additions:

-          START and STOP input jacks, voltage triggered (V-TRIG).

-          External Sample-Hold input jack, bypassing internal voltage sources.

The panel layout is intended to capture some of the “look and feel” of the original, in a Eurorack format.

 1125 Video: