TrigPulser Mini

The TrigPulser Mini is a lo-fi, battery powered noisebox based on the CD4093 NAND Schmitt Trigger logic chip.

Schematic:

What’s basically going on:

The core of this noisemaker is the classic Schmitt trigger oscillator, with the resistance from a potentiometer (VR2, VR3, and VR4 in the schematic) controlling the charge/discharge rate of a capacitor, which translates to the frequency of the oscillator. One of these oscillators is turning a second oscillator on and off via a NAND input for an amplitude-modulation effect, and this second oscillator together with a third independent oscillator feed a NAND gate, the output of which is producing the sound you hear.

This circuit has been tested and verified to work on any voltage from 5V to 12V, but was designed around 9V for the purposes of being compatible with that ubiquitous battery type. At voltages above 9V, it may be desirable to add some resistance to the feedback loops (where the frequency pots are) to act as frequency limiters, because the oscillators will start to go into ultrasonic ranges.

If you plan to run the circuit from batteries, you can increase battery life by increasing the value of R4 (for the power indicator LED). The LED as shown actually draws more current than the rest of the circuit. Note that doing this will of course make the LED dimmer.

Demo video:

TrigPulser Mini- squarewave noise synth

This is a standalone noise synth based on the TrigPulser module I built for the Lunettoid modular noise machine. This version has three squarewave oscillators. One is used to turn another on & …

CC-BY-NC-SA