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 and gate signals out of different sources. Here is one of them. A signal to trigger and gate 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.

Signal to Trigger Converter Module

Signal to Trigger Converter schematic

You can feed the signal in through input one ore two. When both inputs are used the signals are added together in IC1A. When the signal crosses zero from positive to negative a trigger of about 1.2msec is generated at output OUT1. When the signal crosses zero from negative to positive a trigger of about 1.2msec is generated at output OUT3. The gate output (OUT2) stays high as long as the signal is in the positive range or above the range which is set by threshold.

Signal to Trigger Converter Sine

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 shoes the gate signal which stays positive as long the input signal stays positive. On the fourth line you can see the trigger when the signal is going negative. Those pictures are taken without any threshold.

Signal to Trigger Converter Triangle

Signal to Trigger Converter Ramp Up

When feeding in a symmetrical signal you can generate triggers with a phase of 180deg between the outputs. Using the threshold manually or with CV you can move the phase difference around and create interesting rhythmically changing patterns. There are a lot off more options to discover in combining input signals with the CV and the threshold.

Feeding in random signals is interesting as well. My favorite in the moment is feeding a LFO signal to one of the inputs and using the CV threshold input with a very slow LFO signal. So you can generate some triggers every 5 or 10 minutes. I like this as a reminder of my synths “Hey, I am still here running”.

Signal to Trigger Converter Ramp Down

Signal to Trigger Converter Square

Signal to Trigger Converter PCB