The AModulator is an RF signal generator kit designed to be a companion to the popular RF Nomad voltage-controlled shortwave receiver Eurorack module. The AModulator SDIY kit consists of two printed circuit boards and thru hole components required to complete the kit. One circuit board contains the actual electronics of the module, and the other circuit board serves as both the faceplate of the module as well as a touch-plate antenna. The AModulator is a very simple RF oscillator that employs amplitude modulation to vary the amplitude, or “volume” of a radio-frequency signal. The amount of amplitude modulation is directly controlled by the amplitude of an audio signal that is input through a front-panel jack on the AModulator. In short, the AModulator puts those classic squelchy, squealy, hissy sounds of a shortwave radio into your modular, via reception on an RF Nomad! Use your own audio program source to create material to mangle with your RF Nomad.
Using the AModulator
Using the AModulator is simple: Switch on the AModulator, send an audio signal into the Audio Input jack, and tune it in on your RF Nomad. Note that the AModulator is intentionally a very low power output transmitter, so you may have to adjust your RF Nomad’s antenna and RF Gain to be able to pick up the audio program cleanly. This is on purpose for a few reasons:
- This allows you to “Play” the AModulator; varying the antenna position of the Nomad can be used to fade the signal in and out, giving it that vintage shortwave vibe. Notice also that the front panel of the AModulator has a touch-plate “Antenna”. Try touching it in diferent ways, to cause more or less signal to be picked up in your RF Nomad.
- While the FCC5 allows individuals to construct experimental low power transmitters for personal educational use, it is up to that individual to make sure that no harmful interference is generated. The AModulator’s signal output level is so small as to barely be measurable, while still yielding useful results.
- If the signal quality were perfect, you could have just used a patch cord to send the audio signal instead!
Although the simplest patch is to run audio from something like an MP3 player or another Eurorack module into the audio jack, and use the RF Nomad to mangle that audio, there are some other interesting possibilities to explore. Try patching the audio output of the RF Nomad into a mult, and run a copy of the RF Nomad’s audio output signal into the audio input jack on the AModulator. Now you’ve got a feedback loop that has an RF component to it that you can “play” with the touchplate! Weirder still, patch another copy of that signal in to the CV Input jack on the RF Nomad! Crazy feedback fun!
Build Document – Assembly Guide