Basic Utilities

No frills unity gain buffers to create multiple copies of a signal, without loading down the source. Helpful for controlling multiple oscillators from the same voltage source, without affecting the oscillator pitch.

Schematic, as shown, normals the first input to the second. If nothing is plugged into Input 2, all 4 outputs will be copies of Input 1.

BOM

• Resistors
  • 1k (4) – R2, R3, R4, R5
  • 100k (2) – R1, R6
• TL074 (1) – U1
• Audio jacks (5) – J1, J2, J3, J4, J5
• Switched audio jack (1) – J6

Need a boost? Gain gotcha covered. Up to 10x amplification of any signal in a straightforward circuit. I can squeeze one of this in a 10HP 1U module, and have at least one in every set of 1U rails. Super handy for recovering undesirable attenuation.

Bear in mind that the amplification is limited by the power rails and the headroom of the op amp. You can’t input 12V and get 120V, but you can input 1V and get 10V

BOM

• Resistors
  • 1k (1) – R1
  • 10k (1) – R2
• Potentiometer
  • 100k (1) – RV1
• TL071 (1) – U1
• Audio jacks (2) – J1, J2

Better than the Spice Girls … 3 Become 1. This is another utility that I have at least one of in each set of 1U rails. Invaluable for routing multiple audio signals to a single effect or multiple control voltages to a single CV input.

BOM

• Resistors
  • 1k (1) – R7
  • 100k (6) – R1, R2, R3, R4, R5, R6
• Potentiometers
  • 100k (3) – RV1, RV2, RV3
• TL072 (1) – U1
• Audio jacks (4) – J1, J2, J3, J4

Two tools in one! When the pot is at center position*, the signal is completely attenuated. Turn the pot one way and the signal fades to full strength. Turn the pot the other way and the signal fades to fully inverted.

*”Center position” should be in quotation marks. It will be roughly in the center. You could make it perfectly in the center, but it would require trim pots for calibration.

BOM

• Resistors
  • 1k (2) – R3, R4
  • 100k (2) – R1, R2
• Potentiometer
  • 100k (1) – RV1
• TL071 (1) – U1
• Audio jacks (3) – J1, J2, J3

I have a few modules that respond better to triggers than to gates, so this is an invaluable tool for maximizing the usability of those modules.

BOM

• Capacitors
  • 100nf (1) – C1
• Resistors
  • 1k (1) – R9
  • 3.9k (1) – R8
  • 10k (2) – R5, R7
  • 100k (5) – R1, R2, R3, R4, R6
• Diode
  • 1N4148 (1) – D1
• LED (1) – D2
• TL072 (1) – U1
• Audio jacks (2) – J1, J2

This one is a little less obvious than some of the others. The LM393 is used as a comparator, which compares the input signal to the reference voltage, and only let’s the input signal through if it exceeds the set threshold.

Ref Adj pot sets the threshold of the reference voltage. Attenuation pot allows for fine tuning the input amplitude.

What’s it for? Any situation where you want to route control voltage based on amplitude. For example, you can copy a 1V/oct signal, route one copy to one VCO, then the other to the comparator. The comparator can then be set up so that it routes only the highest notes to another VCO, to accent those notes. Or something similar with two VCFs. You get the idea.

BOM

• Resistors
  • 1k (1) – R2
  • 200k (1) – R1
• Potentiometers
  • 50k (1) – RV1
  • 100k (1) – RV2
• LM393 comparator (1) – U1
• Audio jacks (2) – J1, J2

The absolute simplest utility. It doesn’t even require power. Use it when you need to decrease the strength of a signal (audio or control).

Because there is no power connection, you might run into some ground-related issues. Technically everything should be grounded through the input and output cables. But, if things aren’t working as expected, you might need to run a jumper cable to ground on another module.

BOM

• Potentiometers 100k (2) – RV1, RV2
• Audio jacks (4) – J1, J2, J3, J4

This is a stripped down version of the core functionality of Voltage Daikaiju. Scale is used to adjust the amplitude of a voltage signal. Offset is used to add DC to the input signal, offsetting the “ground” reference around which an oscillator (such as an LFO) swings. Useful for tweaking LFOs and envelopes to get more or less effect when used as control voltage.

Includes an inverted output, in case that’s useful for you. Leave it out if it’s not. I’m not the boss of you.

BOM

• Resistors
  • 1k (2) – R3, R6
  • 10k (4) – R1, R2, R4, R5
• Potentiometers
  • 100k (2) – RV1, RV2
• TL074 (1) – U1
• Audio jacks (3) – J1, J2, J3

This is a surprisingly useful, and crazy simple, utility. Use it to boost or add positive DC offset to control voltage. It’s also great for something like Electric Druid’s ENVGEN ADSR chip–I use it to dial in a constant voltage to maintain attack and sustain at desirable levels.

BOM

• Capacitors
  • 100nf (1) – C1
• Potentiometers
  • 10k (2) – RV1, RV2
• Audio jacks (2) – J1, J2
• L78L05 voltage regulator (or similar) (1) – U1

Standalone glide (aka glissando or portamento, for those not versed in Mooglish) for making those classic Gary Numan sounds.

BOM

• Capacitors
  • 2.2uf electrolytic (1) – C1
• Resistors
  • 1k (1) – R1
• Potentiometer
  • 500k (1) – RV1
• TL072 (1) – U1
• Audio jacks (2) – J1, J2