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Category Archives: case building




here is a little jam to test the possibilities of my recently finished step sequencer…this little gadget is so much fun, and opens up my head of possibilities…i have to write a proper post with circuit and instructions on how to build it i will just say for now that is made with a single 4017 that can trigger 4 different channels on each of the 10 possible steps.

here comes the sound…

…on the video I’m playing the sequencer and the SP-404 sampler trying to match tempo…and the sp404 is also filtering the sequenced sounds at times…and the drum pattern at others….the step sequencer is triggering the sounds of a toy circuit which i modified adding also pitch and distortion controls….plus the jacks connect the 4 channels of the sequencer to the desired sound bank on the toy…


this are some images of the process of building the 4017 step sequencer and a little circuit diagram…the construction was not difficult but  tedious….

9volts 2009


DRONE sounds SYNTH, cased inside an old router box. Chaotic but under control.


The circuit for this instrument is quite simple, four 555 in astable configuration gating and four oscillators made with just one 4093.


click to enlarge

The interface is arranged as four channels across,each one has three switches and two potentiometers, and LED showing it’s state:


So for each channel, the first pot (50k) controls the freq of pulse coming out from the pin3 of each 555; this signal can be routed to main out (resulting on a pulse beating oscillation) or to gate each of the 4 oscillators made with the nand gates of the 4093. the second pot (1M) controls the pitch of the gated oscillators on IC 4093. the switches allow for some tweaking on each channel, either pulse ore gated/osc mode,also the indispensable channel on/off, and finally the third switch connects the pins 5 of the 555 (voltage control?) to the main out resulting on some interesting broken rhythmic patterns…for some magic of electronic randomness…All switches positions can be use combined into several different modes,and like always (I’m not an engineer) the oscillators affect and modulate each other..sometimes beautiful harmonies occur inside the rhythmic pattern…drone2



The result is an instrument that is fun to play, because while it has it’s random magic sound remains totally controllable.

Here is a video of the DRONE in action performed by 9volts & ChairB and recorded by LucySombra.

video of PyR 2009 | PyRformance Alba G. Corral + Nikka

Nikka is owner and user of Drone Synth

This time, the goal was to build a little instrument, to be played by hands, this kind of device is often called an opto-theremin…


In this case I build the circuit from scratch using a similar schematic as in my little hex-schmitt trigger synth, but instead of the IC 74c14 I used the 4093, which is a Quad 2-input NAND Schmitt trigger; This is a great IC to build oscillator-synths because it allows you to gate each output with a switch or with another oscillator…

here is a diagram of the 4093 IC connection pins:

4093 pin conections
4093 pin connections

and here is the schematic for the 4LDR synth:


note that i wrote the values of components guessing what i used because i don’t remember exactly, anyway you can play with different values to achive the sound performance that you prefer…. as it can be seen in the diagram, the Light dependent resistors are placed in series with little faders which allows to adjust the range of response of the LDRs;

what does what-ldr-synth

and here a video of me testing the little instrument, where you can hear all the r2d2-like sounds which this instrument is able to make…this little synth is one of the most fun and intuitive instruments i had build until now, and it is also my wife’s favourite…

by 9volts


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