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Introduction

Thanks for purchasing the SDIY

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MDRONE kit from Evaton Technologies!  The 

SDIY  MDRONE kit   is  a battery-powered  standalone  tabletop  drone synth  that 
can  be  built  in  just  a  few  evenings. The SDIY  MDRONE kit  is  available as  just 
parts and PCB (build your own case), or as a complete parts + PCB + pre-drilled 
enclosure, for those who wish to get up and running right away

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The SDIY  MDRONE voice architecture consists of three independent square-

wave oscillators, which are mixed in a fixed summing mixer. The mixer output 
is then fed to a semi-resonant bandpass filter, with adjustable center frequency 
and bandwidth. A “Grit” setting allows overdriving the filter for dirtying-up the 
sound and making a more hard-hitting timbre. 

Output is a 1/4” mono (TS) line-level audio jack. 

Skill Level

The SDIY  MDRONE kit,  while not  necessarily  aimed at  the complete novice, 

can  be  built  by  anyone  with  some  soldering  experience.  All  components  are 
standard,  readily-available  thru-hole  components.  The  spacing  of  the 
components  on  the  circuit  board  is  generous,  so  that  no  special  tools  are 
required to  install. These instructions assume you already know how to solder, 
and cut and strip wires. 

Precautions

Soldering  irons  are 

HOT

!  Be careful  not  to  touch  the  business  end of  your 

soldering iron at  any  time. Also  note that  components that  have been soldered 
will remain hot for a few moments. If you need to hold something to solder it, it 
is recommended 

NOT

 to use your fingers. Wear long pants and long sleeves to 

avoid solder splash from burning exposed skin. 

   

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 Synthesizer Do-It-Yourself

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 If you purchased this kit as a complete parts + PCB + enclosure kit, additional instructions for the 

enclosure will be included in your shipment.

SDIY MDRONE

Assembly Manual

Revision A - Parts & PCB Kit

200 School St

Pittsburgh, PA 15220-2718

http://www.evatontechnologies.com

/

Summary of Contents for SDIY MDRONE

Page 1: ...cessarily aimed at the complete novice can be built by anyone with some soldering experience All components are standard readily available thru hole components The spacing of the components on the cir...

Page 2: ...optional for holding the PCB Small adjustable wrench or 10mm deep well socket for tightening potentiometer nuts 9 32 open end wrench for tightening toggle switch nuts De soldering braid optional for...

Page 3: ...who d like to get a little more acquainted with electronics Please see the included schematic diagram to follow along4 The schematic is divided up into a few logical sections The oscillators the summ...

Page 4: ...OSC 3 work the same way Summing Mixer U1A is an operational amplifier op amp It adds together the three signals coming through R2 R4 and R18 An op amp connected in this configuration is called a Summ...

Page 5: ...tion a more thorough description of how the filter does this is beyond the scope of this manual Further reading is suggested if you want to gain a better understanding of op amp filters5 Kit Contents...

Page 6: ...cing you The next few paragraphs will go step by step through the process of assembling the circuit board You may wish to check these steps off as you go to keep track of your place ____ Sockets First...

Page 7: ...8 switches The switch is ON when the toggle lever is pointing away from the pair of pins you ve soldered to Now solder the other end of one of those wires to the hole marked P6 on the PCB Solder the o...

Page 8: ...e to the lead of R6 that is nearest the edge of the PCB Turn the power switch ON The multimeter should read 9 volts Now with the negative lead of the multimeter still touching pin 7 of the U2 socket t...

Page 9: ...m ____ 1 0 F Capacitors The 1 0 F capacitors are polarized electrolytic capacitors These are the timing capacitors for the three oscillators Because they are polarized you must pay attention to which...

Page 10: ...are 100k linear potentiometers one is a 100k audio taper pot and one is a 5k audio taper potentiometer The PCB outline for the potentiometers has three numbered pads These correspond to the three legs...

Page 11: ...g leads on the pots Although there are rivet holes on the pot it s best to solder to the long leads which put the solder iron heat a little further away from the inner mechanism of the pot Ok with tha...

Page 12: ...to each of the three leads on the 100k audio A100K potentiometers Solder the other ends of these wires to the pads for R13 Label this potentiometer Filter Frequency Fc ____ Toggle Switches Next solder...

Page 13: ...l still cause a slight amount of dirt when in Non Grit mode but for the most part will be clean To select between Grit and Non Grit you need to decide the value of the resistor R21 If you want Grit mo...

Page 14: ...n the integrated circuit at one end Make sure this notch faces the end of the socket nearest the U1 label It should match the notch in the socket if you installed the socket correctly You may need to...

Page 15: ...otentiometer R1 Now rotate the Filter Width R23 potentiometer The sound color should change Likewise for the Filter Frequency R13 potentiometer Finally rotating the Volume knob should make the sound g...

Page 16: ...Width and Filter Frequency knobs can be used to alter the harmonic content timbre of the drone Turning the Grit switch on and off if you ve implemented this feature selects between mostly clean audio...

Page 17: ...ollowing diagram Now toggling this switch shifts the center frequency of the bandpass filter very low In combination with the Grit this can make some interesting sounds Experiment with different value...

Page 18: ...o the end of R5 that is nearest the edge of the PCB What this circuit bend does is to shift the voltage level of the virtual ground much closer to zero volts This destabilizes the filter causing it to...

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Page 21: ...N ON ON OFF OFF OFF ON OFF OSC 1 Fc Q ON OFF OSC 1 Volume OSC 2 OSC 3 Filter evaton technologies SDIY MDRONE OSC 1 Power ON ON ON OFF OFF OFF ON OFF OSC 1 Fc Q OSC 1 Volume OSC 2 OSC 3 Filter evaton t...

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