We haven’t had a circuit sculpt in a while, so here’s “ioalieia” a nice digital-analog hybrid sound sculpt from [Eirik Brandal] to dig. The host of the broadcast is the ESP32 module, which generates square waves of audio frequency, which are fed into an MCP4251 digital potentiometer. From there it is fed into an AS3320 Voltage Controlled Filter (VCF), from Latvia based ALFA (which is new to us, although they have been making electronics for sixty years!) This is an interesting device with four independently configurable filters. elements with voltage controlled inputs for frequency control and resonance. The output of the VCF is then fed into a 6n2p (Soviet equivalent of 12ax7) dual triode vacuum tube, which is specifically intended for audio applications.

The suitably distorted filtered square waves then pass through a Princeton Tech Corp PT2399 echo processor cjip, which being digitally built, uses the expected ADC/RAM/DAC signal chain to implement an audio echo effect. As with the VCF, the echo depth can be modulated via the digipot, under control of the ESP32. For a bit more bling, the output of the vacuum tube is fed back into the ESP32, to be consumed by the internal ADC and turned into a light show via some PWM-controlled LEDs. Beautiful.

The final audio output from the echo chip is then fed into a loudspeaker through a pair of LM380 amplifiers giving around 5W of power. Sounds pretty good if you ask us, and software configurable over Wi-Fi, giving this sculpt plenty of tweakabilty.

Of course, circuit carving comes in all shapes and sizes, and it wouldn’t hurt to mention at least one carving clock project, and while we’re at it, here’s the carving workshop of distance circuit last year.