Logic II (AND, OR, XOR, NOT)

Logic II: Front view
Logic II: Front view

This logic module takes up to four input signals and outputs the logic function AND, OR, XOR dependent on the input signals. The inputs are normalized so you can use less then the four inputs. It has three NOT functions as well.

Specs and features

  • Up to four input signals
  • AND, OR, XOR parallel out
  • Three NOT functions
  • Runs on +/-12V and +/-15V
  • Power consumption below 30mA positive rail. 5mA negative rail.

The documentation and the Gerber files for download can be found in my website.

Logic II: Control board schematic
Logic II: Control board schematic
Logic II: Main board schematic
Logic II: Main board schematic
Logic II: Populated control board
Logic II: Populated control board
Logic II: Populated main board
Logic II: Populated main board
Logic II: Back view
Logic II: Back view
Logic II: Half front view
Logic II: Half front view
Logic II: Side view
Logic II: Side view

Logic I

Logic I:Front view

This logic module takes up to four input signals and outputs the logic function AND, OR, XOR dependent on the input signals. The inputs are normalized so you can use less then the four inputs.

Specs and features

  • Up to four input signals
  • AND, OR, XOR parallel out
  • Runs on +/-12V and +/-15V
  • Power consumption below 30mA positive rail. 5mA negative rail.

The documentation and the Gerber files for download can be found in my website.

Logic I: Schematic control board
Logic I: Schematic control board
Logic I: Schematic main board
Logic I: Schematic main board

Nothing special to mention. On page one you see the input and outputs. On page two are the input protection circuitry, the microprocessor and the output buffers. The logic is done in software.

Logic I: Populated control board
Logic I: Populated control board
Logic I: Populated main board
Logic I: Populated main board
Logic I: Back view
Logic I: Back view
Logic I: Side view
Logic I: Side view

Dual Bernoulli Gate (Either/Or)

Bernoulli Gate: Front view
Bernoulli Gate: Front view

This module takes the incoming gate or trigger and routes it to either of its two outputs. The distribution is software driven, according to a random coin toss. You can select the probability distribution with a potentiometer and an input control voltage. The potentiometer voltage and the control voltage are added together. The probability goes from 0% to 100% at output A and from 100% to 0% on output B.

Specs and features

  • Randomly skip Gates and Triggers
  • Probability distribution voltage controlled
  • Dual Bernoulli gate
  • Runs on +/-12V and +/-15V
  • Power consumption below 20mA positive rail. 5mA negative rail.

The documentation and the Gerber files for download can be found in my website.

Bernoulli Gate: Schematic control board
Bernoulli Gate: Schematic control board
Bernoulli Gate: Schematic main board
Bernoulli Gate: Populated control board
Bernoulli Gate: Populated control board
Bernoulli Gate: Populated main board
Bernoulli Gate: Halve back view
Bernoulli Gate: Halve back view
Bernoulli Gate: Side view
Bernoulli Gate: Side view

Rotating Gate

Rotating Gate: Front view

With this module you can distribute the incoming gate or trigger up to eight outputs. The distribution is software driven. You can select the amount of the used outputs from zero to eight with a potentiometer and an input control voltage. The potentiometer voltage and the control voltage are added together. The mode potentiometer and the mode control voltage selects the algorithm for the distribution. As for the moment (2021 Nov.) only one mode is implemented. Rotating upwards. Any suggestions or programs are welcome.

Specs and features

  • Gate/Trigger distribution up to eight targets.
  • Number of used outputs voltage controlled
  • Distribution algorithm voltage controlled
  • Runs on +/-12V and +/-15V
  • Power consumption below 20mA positive rail. 5mA negative rail.

The documentation and the Gerber files for download can be found in my website.

Rotating Gate: Schematic control board
Rotating Gate: Schematic control board
Rotating Gate: Schematic main board
Rotating Gate: Schematic main board
Rotating Gate: Populated control PCB
Rotating Gate: Populated control PCB
Rotating Gate: Populated main PCB
Rotating Gate: Populated main PCB
Rotating Gate: Back view
Rotating Gate: Back view
Rotating Gate: Side view
Rotating Gate: Side view

Gate Delay

Gate Delay: Front view

This module starts as a need for my Shakuhachi 2 Synth project. I was in need for a short Gate Delay of about 10ms (which is easy to realize). But then I thought about a more flexible solution with adjustable delay time and optional trimming the gate at the end. To be used elsewhere in the synth as well. So I came up with this solution. The hardware is still simple and the functionality lies in the software. So far I have only realized the function which I need for my Shakuhachi to Synth project. But you can easily improve about this with changing the software.

Specs and features

  • Gate delay with variable timing
  • Coarse and fine time adjustment
  • Gate in and out with LED signaling
  • End of gate trim
  • Runs on +/-12V and +/-15V
  • Power consumption below 30mA positive rail. 5mA negative rail.

The documentation and the Gerber files for download can be found in my website.

Gate delay: Schematic control board
Gate delay: Schematic control board
Gate delay: Schematic main board
Gate delay: Schematic main board
Gate delay: Populated control PCB
Gate delay: Populated control PCB
Gate delay: Populated main PCB
Gate delay: Populated main PCB
Gate delay: Back view
Gate delay: Back view
Gate delay: Side view

BPM Generator 20..2400 BPM with dividers

BPM Generator 20..2400 BPM with dividers: Front view
BPM Generator 20..2400 BPM with dividers: Front view

This is the enhanced version of my BPM-Generator in combination with my Clock Divider 2..8 and Clock Divider with primes adapted for Eurorack. The range goes from 20BPM up to 2400BPM. Pulses at 5V/20ms. All 16 outputs are synchronized and work in parallel. Divisions are 1, 2, 3, 4, 5, 6, 7, 8, 11, 13, 17, 19, 23, 29, 31 and 37. You have a start/stop input for the BPM generator and a reset input for the dividers. A 4 digits display shows the current BPM. You can store the latest timing with keypress.

Specs and features

  • 20..2400 BPM
  • All outputs 5V/20ms
  • 16 outputs
  • Start/stop input
  • Divider reset input
  • 4 digit display
  • Power consumption around 5mA negative rail, 50mA positive rail

The documentation and the Gerber files for download can be found in my website.

BPM Generator 20..2400 BPM with dividers: Populated control PCB
BPM Generator 20..2400 BPM with dividers: Populated control PCB
BPM Generator 20..2400 BPM with dividers: Populated control PCB backside
BPM Generator 20..2400 BPM with dividers: Populated control PCB backside
BPM Generator 20..2400 BPM with dividers: Populated main PCB
BPM Generator 20..2400 BPM with dividers: Populated main PCB
BPM Generator 20..2400 BPM with dividers: Side view
BPM Generator 20..2400 BPM with dividers: Side view
BPM Generator 20..2400 BPM with dividers: Back view
BPM Generator 20..2400 BPM with dividers: Back view

Sequencer Nostalgia

This was my first build when I came back to SDIY. A three row/16 step sequencer. Completely build on stripboard. Still working after all this years. Only hand sketched schematics. Nothing to publish. Pictures only.

Sequencer three rows/16 steps: front
Sequencer three rows/16 steps: front
Sequencer: Clock close up
Sequencer: Clock close up front
Sequencer: Clock close up back
Sequencer: Clock close up back
Sequencer: Inside
Sequencer: Inside
Sequencer: Inside
Sequencer: Inside

ADSR Euro-rack

ADSR: Front view
ADSR: Front view

This is another derivation off the ADSR for my NGF-E project, adapted to 12V Euro-rack format. Because this one is a stand alone module I have removed all additional features from the Next Generation Formant project. Nonetheless it is still based on original Elektor Formant ADSR schematic. I made some error corrections and added my changes to the design. All parts are updated to today (2021/01) available parts. I have made a few changes to fix some shortcomings of the original. A triple range switch was added for finer adjustment of the ADSR CV-output signal. The attack rise time is shorter now as in the original. The gate input is buffered. The fixes a fault in the original when working with analog sequencers. The output voltage is slightly raised to reach really 5V. Due to the design of the original Elektor Formant ADSR the output of the original ADSR keeps a residual voltage of about 0,5V. I have put an compensation in my design to correct this. The driver circuitry for the output indicator LED is changed for better linearity.

Specs and features

  • AD/ADSR switch
  • Gate input 5V
  • CV output ..5V
  • CV output indicator
  • Range switch: fast, middle, long
  • Attack (A) 0,5ms…16s
  • Decay (D) 4ms…40s
  • Sustain (S) 0..5V
  • Release (R) 4ms..40s
  • Power consumption below 15mA each rail

The documentation and the Gerber files for download can be found in my website.

ADSR: Schenmatic main PCB
ADSR: Schematic main PCB
ADSR: Schematic control PCB
ADSR: Schematic control PCB

This is a close clone of the Elektor Formant ADSR. Here i only describe the changes i have made. The description of the other parts of the circuitry can be found in the original Elektor Formant documentation. The gate signal input resistance is raised from 33kOhm to 1megOhm with the input buffer IC1A. This protects against double triggering with the falling edge of the gate signal when using sequencers. R30 is used to fix the input to a defined potential when no signal is attached to the input. C1 was lowered to 6n8 from 10nF. In combination with C2 and the raised charging voltage through IC1B/R9 this makes for faster attack time. The load capacitor of 10u was replaced with three selectable capacitors of 2,2uF 4,7uF and 10uF. This makes for a finer adjustment of the response times of the ADSR. The voltage divider R19/R21 was adjusted to ensure that the output level of 5V is reached. If this feature is not used R25 should be lowered to 5k1. Construction conditioned the output at IC1D only reaches a minimal voltage of about 0,5V. To compensate for this i added IC2A. If the ADSR is not used the output voltage is now at -0,5V. The current consumption was lowered with using the TL064 and a low current LED.

ADSR: back view
ADSR: Back view
ADSR: Populated main PCB
ADSR: Populated main PCB
ADSR: Populated control PCB
ADSR: Populated control PCB
ADSR: Side view
ADSR: Side view

Signal to Trigger Converter

Signal to Trigger Converter: Front view
Signal to Trigger Converter: Front view

This module was originally build for my Shakuhachi to Synth project to provide the start/stop pulse for the Pitch to voltage converter. But it turned out to be much more useful. When you have the basics for your synthesizer like VCO, VCF, VCA, ADSR, LFO,… and some controllers and you want more, then using your keyboard to steer the synthesizer it is time for some modules to produce trigger signals out of different sources. Here is one of them. A signal to trigger converter. You can feed in a changing signal and every time the signal went through zero a trigger is generated dependent on the direction from where the zero point is crossed. You can add a threshold manually or CV controlled to move the zero point up or down as well. You can feed the signal in through input one ore two. When both inputs are used the signals are added together. When the signal crosses zero from positive to negative a trigger of about 0.1msec is generated at output -Trig. When the signal crosses zero from negative to positive a trigger of about 0.1msec is generated at output +Trig. Output +/-Trig provides both triggers. This output can be used to generate interesting rhythmic patterns when the threshold is set by a slowly moving CV or some DC offset is applied to the signal.

Specs and features

  • Two added inputs
  • Threshold manually and with CV
  • Output for +Trig, -Trig and +/-Trig: 0.1msec
  • Runs on +/-15V and +/-12V with minor resistor changes
  • Power consumption below 25mA each rail

The documentation and the Gerber files for download can be found in my website.

Signal to Trigger Converter: Schematic control board
Signal to Trigger Converter: Schematic control board
Signal to Trigger Converter: Schematic main board
Signal to Trigger Converter: Schematic main board
Summed signal to trigger
Summed signal to trigger

The incoming signals are summed up. Every time when the summed signal changes polarity (moving through zero) a trigger is generated. Moving from plus to minus generates a trigger at the negative trigger output, moving from minus to plus generates a trigger at the positive trigger output. Trigger length is about 0.1msec.

Screenshot sine to trigger
Screenshot sine to trigger

The uppermost line (Yellow) shows the input signal. The second line (Blue) shows the trigger when the input signal moves to the positive site. The third line (Purple) shows the trigger when the input signal moves to the negative site. On the fourth line (Green) you can see both triggers added. This picture is taken without any threshold.

Signal to Trigger converter: Back view
Signal to Trigger converter: Back view
Signal to Trigger converter: Side view
Signal to Trigger converter: Side view