Analog Synthesizer using PIC

This project presents an audio synthesizer but not only that, it gives some ideas on how to interface other synths to a keyboard. The keyboard decoder uses the 74HC154 IC and the PIC18F1220. The 4 bits binary input of the 74HC154 is connected to the PIC which will cycle from 0 to 11, representing the twelve semitones. This in turn will cycle the outputs but with low logic level.

The octave is determined directly by the PIC. When a key is pressed it will make the  corresponding octave line connect with the corresponding semitone output of the 74HC154 and thus turning the octave line from high to low level. When this is sensed by the PIC, it will check at which semitone the cycle was and output the musical note and the envelope trigger.

After that the PIC oscillators output are sent into separate wave shapers where you can select three types of waveforms. The waveforms are then summed and go into the VCF which can be controlled manually, by the envelope generator or modulated by oscillator 1. After VCF comes the VCA formed with a differential pair, with the control voltage modifying the emitter current.

Newer software has features like arpeggiator or portamento. With this way of interfacing the keyboard there will be some limitations to its usage. For example only the high note will be played if two notes are pressed the same time. All the instructions needed to build this are given however the code for the microcontroller is not but there is enough information to write it yourself.

Analog Synthesizer using PIC: [Link][Via]

May 8th, 2009

Drone Lab Synthesizer

Drone Lab Synth

If you like electro music and buttons here is something very good for you. A synthesizer that has 15 control knobs, 4 switches and 2 LEDs and still you can hold it in the palm of your hand. It allows you to shape all kinds of weird sounds and despite its big number of controls it is not a difficult project.

The sounds coming from this synthesizer are from four oscillators,  usual inverters with an integrator in feedback. . You can control their rate of oscillation and modulate the pitch or volume, adjust the cut and resonance of low pass filters and  feed the signal into a fuzz stage. By linking two dividers to the output of a LFO some interesting rhythms can be achieved.

Because we are dealing with oscillators you must be careful of how you wire and solder the electronic components or you will have to deal with stability problems. Also put the potentiometers’ shield to ground, easily done if your using a metal case. A 9V battery can power this synth for a a pretty long time.

The Drone Lab can give you more than awesome sounds by using the dividers’ outputs as gate outputs to some other devices. This way you can use the rhythmic modulator with other sound generators. Happy soldering.

Drone Lab Synthesizer: [Link][Via]

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