/:P2/:AS3340

AS3340 VCO

An implementation of the Electric Druid's Voltage Controlled Oscillator(VCO) AS3340.

Project Duration 4 months

Status Completed

Year 2026

Audio Demos

A few recordings of the prototype in action, captured straight from the VCO output into the audio interface.

Random 1 shots

Simple ADSR and filter chain in ableton. VCO output to audio interface.

PWM, Sine, Triangle and Saw sweeps

Sweeps to display course and fine tune.

Sine bass

Sine bass made with the VCO. Recorded a clip of sine and used STING midi generator to get the bassline.

Sine sample

The sample used for the clip above.

Bill of Materials

This design of the board was based on N8Synthesizer's AS330 VCO project. Since their version features a sine output and a clear schematic I used it as a starting point, along with all their documentation.

Bellow is the link to their Bill Of Materials:

N8Synthesizer's AS330 VCO BOM

BOM used as a reference for this project.

Tools Used

Siglent SDS804X DSO

Digital Storage Oscilloscope for signal analysis and debugging and documenting.

70 MHz Probes

PB470 70MHz 1X&10X Oscilloscope Probes

Solder Station

WE1010 solder station"

Focusrite Scarlett 8i6

Audio Interface for testing and recording the signals.

3.5mm jack to 6.35 mm jack cable

Used to connect VCO to audio interface

Diagrams & Schematics

N8 Synth's circuit diagram.

N8Synthesizer's AS330 VCO BOM

Circuit diagram used as a reference for this project.

Electric Druid's classic CEM3340 VCO designs.

Electric Druid's CEM3340 VCO design

Design used as a reference for this project.

AS3340 pinout.

Assembly Process

PCB Fabrication

Designed and fabricated the LNA PCB using Rogers RO4003C substrate for optimal RF performance at microwave frequencies.

Component Assembly

Soldered the BGA2803 MMIC and PE4259 RF switch with careful attention to thermal management and RF grounding.

Filter Integration

Integrated three SAW bandpass filters covering shortwave, VHF, and UHF frequency ranges.

Software Setup

Configured Raspberry Pi GPIO for filter switching and set up GNU Radio flowgraphs for various demodulation modes.

Oscilloscope Analysis

LNA Gain Response

Measured 21 dB gain across 100 MHz–2 GHz with 0.9 dB noise figure.