|1930 - meetup|
|DIY Modular Synth aka Samohrajka|
|status:||testing & designing circuits|
Goals of this project:
I've ordered small strobe from china, so once it arrives i can tune it on 10Hz and synchronize the noise with it. And i believe this can make audience in small darkened room of hackerspace pass to their inner hyperspace (or to photosensitive epilepsy shock).
I've been trying to build two simple RC filters, here are the results:
Another toy i've made:
Added another oscillator (wannabe CMOScillator AM modulation)
PhotoTransistor + Remote Controls = Noise Jam
First prototype - DIY toy hardly inspired by Korg Kaossilator and Monotron…
CMOS oscillators are not capable of generating analogue signal on their output, but the voltage on capacitor of those oscillators is purely analogue. You can see what i've captured using soundcard attached directly to the capacitor of my “CMOScillator”: So we can use MOSFET to amplify the voltage on such capacitor and voila - we have analogue LFO!!! (I've chosed MOSFET because CMOS logic is made from MOSFETs and because current can flow in both directions through the MOSFET, so we can use it to drive another “CMOScillator” directly).
The shape of the LFO signal can be slightly altered to produce sine, saw-up and saw-down functions by replacing CMOScillators resistor by two resistors (or pots) distinguished using two diodes, so you will be able to have different capacitor charging and discharging time.
HardTekno DrumLoop generated usin saw-down LFO (4093 + LED across potentiometer) and simplest possible CMOS VCO. + bit of messing with circuit (eg.: Sonic Devastator Redesign as a bonus).
Schematic of simple VCO using CMOS 4046. Note that i am attaching VCO input directly to positive pin of LFO capacitor (instead of voltage-divider shown in picture), so i can drive the VCO using almost-saw signal from 4093 oscillator. Also note that 4046 VCO (thanks to voltage-driven MOSFET/CMOS technology) does not suck almost any current from the LFO capacitor, so it does not detune it (and i do NOT need any external discrete MOSFET transistor to amplify that signal as originaly wanted to do).
Here you can see some signals from VCO (upper graph) and LFO (lower graph) that i've caputred using soundcard and audacity: