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OSKITONE OKAY 2 Synth, Assembly Manual

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OSKITONE OKAY 2 Synth Assembly Manual Download Page 19

 

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The included potentiometer is linear but would actually 
be better if it were logarithmic, due to the way humans 
interpret volume. Luckily, it’s easy to to approximate a 
logarithmic response by connecting the ground and 
output pins (left and middle, when viewed from the 
top) with a smaller resistor. Further investigation is left 
as an exercise for the reader. (Hint: google “fake log 
pot”) 

 

 

 

 

Summary of Contents for OKAY 2 Synth

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Page 2: ... www oskitone com product okay 2 synth diy kit Last updated 2018 02 18 All rights reserved This book or any portion thereof may not be reproduced or used in any manner whatsoever without the express written permission of the publisher except for the use of brief quotations in a book review http www oskitone com Instagram Twitter oskitone ...

Page 3: ...e know how it goes what you think and or if you run into any trouble Reach me at tommy oskitone com You can also find last minute guide updates extra assembly information and videos at http www oskitone com guides Otherwise good luck take your time and have fun Tommy ...

Page 4: ...crete electronic components like capacitors and resistors and logic chips Square wave When its output is viewed on an oscilloscope its wave resembles a square It s a hard sounding wave type great for bass lines and commonly associated with chiptune music and old video games OKAY versions There are two versions of the OKAY OKAY 1 Also just called OKAY since it came out first One octave of keys 13 k...

Page 5: ...ly 4 PCB assembly a General tips b Connecting wires c Wiring diagram d 386 0 1 1 i Wiring the jack for OKAY 2 only e 555_4040 01 1 1 i Wiring the rotary switch f bus 0 1 1 i Polarity on middle pads g SPST_VR 0 2 2 i Wiring for OKAY 2 5 Putting it all together a Testing and debugging b Final assembly c Tuning d Care 6 Appendix Circuit schematics ...

Page 6: ... a Top No Normal n a Hinge parts No Normal n a OKAY hold in No Normal n a Keys No Light 12 8 13 8 Key plungers No Normal n a Speaker No Normal 5 4 Labels No Normal 6 4 OKAY text No Light 9 8 9 4 Knobs No Normal 18 4 Key cradle No Normal n a key plungers are only for OKAY 1 key cradle is only for OKAY 2 first value is for OKAY 1 second is for OKAY 2 Refer to http oskitone com guides for additional ...

Page 7: ... printing 1 Clean up strings a Cut or melt away any stringing Be careful not to scratch dark filament underneath text embossing 2 Remove built in supports a Break built in bridge supports from each PCB post with a small screwdriver or other stabby object b For the OKAY 2 do the same for the key cradle 3 Knobs a Cut built in bridge support from bottom to expose shaft cavity b One knob has a hole in...

Page 8: ... printed parts Bottom Top Hinge links 4 Latches 2 Key overlays Key plungers 13 OKAY 1 only OKAY text OKAY text hold in tab Speaker grill Knobs 2 1 w tension screw 1 w o Knob labels Key cradle OKAY 2 only Filament 7 Miscellaneous 4 40 screws OKAY 1 16 17 OKAY 2 6 7 4 40 screws OKAY 1 0 OKAY 2 23 4 40 hex nuts OKAY 1 16 OKAY 2 29 ...

Page 9: ... cutters Needle nose pliers Philips screwdriver Precision flathead screwdriver Chromatic instrument tuner Elmer s glue 9v battery Ruler for measuring wire Recommended Multimeter for debugging Wire stripper PCB vice or helping hands holder Solder sucker or desoldering braid Tweezers or dentist s tools for working with small components Hot glue Zip ties for tidying up wires Utility knife Jumper wire...

Page 10: ...n the enclosure top b Secure its underside with the hold in tab 4 Keys a For the OKAY 1 i Pull the key overlays in through the top of the enclosure and affix onto the row of dovetails Gently push into place ii Using a smalls screwdriver in its holed tabs pull the keys more securely onto the enclosure top b For the OKAY 2 i You ll first need to solder the SPST_VR PCBs so skip this part for now and ...

Page 11: ... glue or by melting it in place with a soldering iron Do the latter in a well ventilated space please 7 Finish OKAY text a With the enclosure closed and the OKAY text secured by both its hold in tab and the key overlays put a small amount of glue in the cavities in its O and A letters b Place the corresponding filler pieces into each cavity c Wipe up any residue glue and leave to dry ...

Page 12: ...itors are small circular and have no polarity they can be placed in either direction Electrolytic caps are bigger cylindrical and have marked polarities Component naming conventions For these PCBS C capacitor R resistor Headers are typically labelled what they are Vertical resistors To save space all the resistors stand vertically instead of lay flat on the PCB Capacitor footprints are small Also ...

Page 13: ...ass capacitors All the ICs use what s called a bypass or decoupling capacitor to prevent noise from other parts of the circuit or even from the power itself from affecting its IC ICs in sockets Each IC chip comes with a corresponding socket with the same number of pins You will solder the socket to the PCB not the chip itself This prevents overheating the IC with the soldering iron and makes it ea...

Page 14: ...040 output pins to rotary switch and back to 386 input 8 rainbow with 7 conductors Power S1 on bus PCB to switch on back of volume pot 6 twisted 2 wire LED Bus PCB slot to LED on volume label 8 or 6 twisted 2 wire Speaker Speaker header on 386 to speaker 6 or 8 twisted 2 wire Volume VOL header on 386 to volume pot 7 rainbow with 3 conductors 386 power 386 power header from bus slot 3 twisted 2 wir...

Page 15: ...Wiring diagram ...

Page 16: ...bber circuit to suppress self oscillation noise R1 10 brown black black Part of snubber POW Power Connects to bus PCB INP Audio input The pin will connect to the rotary switch The pin can be omitted for the OKAY because all boards share the same ground DIST Distortion switch Should be omitted for the OKAY VR1 VOL Volume potentiom eter VR1 and and the VOL header redundantly expose the same three po...

Page 17: ...tiometer from the top with its shaft pointed at you and the leads pointing down The left pot lead will connect to the left VOL header pad labeled as ground The other two connect in order middle to middle and right to right SPK Speaker Connects to speaker or output jack The pin touching ground is labelled as negative the other is positive IC1 LM386 Amp IC chip in socket ...

Page 18: ...in transit Luckily fixing it is also simple There are two extending contact limbs and they should touch by default and not touch when the something is inserted If that s not the case gently bend into the correct position Experiments to try Try a higher value capacitor for C3 for a beefier sound Connect the input to a different sound source like another small instrument or your phone Put a 10uF cap...

Page 19: ...c due to the way humans interpret volume Luckily it s easy to to approximate a logarithmic response by connecting the ground and output pins left and middle when viewed from the top with a smaller resistor Further investigation is left as an exercise for the reader Hint google fake log pot ...

Page 20: ...t octaves The 12 octaves are exposed on the right side of the board grouped in halves from 1 6 and 7 12 The raw output of the 555 octave 0 is accessible by the unlabeled single header pin to the bottom right of IC1 Name Value Explanation C1 10nF 103 Sets oscillator frequency on IC1 C2 10nF 103 Ties Control voltage IC pin on IC1 to stable power minimizing spurious noise C3 1uF 104 Bypass capacitor ...

Page 21: ...h has six positions which will each connect to a different octave output The switch s common lead is the switch s decision position To identify which of the 12 rotary switch s pins to use mentally draw a line between the center two pins to make two semicircles Each semicircle is an isolated but identical circuit of six position pins on the outside and one common pin towards the middle Choose eithe...

Page 22: ...ckwise to go down Because you ll solder the switch upside down with its pins pointing up the most clockwise pin will be the lowest note Experiments to try Replace C1 with a capacitor of lower value for a higher frequency or a higher value for a lower frequency Try a different value for R1 Just like C1 a higher value makes a lower frequency and vice versa You can actually mix the 4040 outputs to cr...

Page 23: ...only audible when the lower frequency allows If you send each output through its own resistor maybe around 10k ohm their sounds will mix together instead of modulate ...

Page 24: ...ed brown Each of these modifies the input power to a respective output power to its right For those connecting to other PCBs a diode here will prevent a mistakenly reversed battery from frying any of the IC chips Position the diode so that its blackened end is on the negative pad See below For the LED a resistor prevents too much current from frying the LED on right Output power Connects to anothe...

Page 25: ... to the S1 switch and then is distributed across the middle pads from this orientation the left pad of each pair It then goes to each of the output pads The positive lead of each of the middle pad pairs is therefore the one touching S1 and the negative is touching its respective The thinner dashed lines indicate ground They are all connected together unconcerned by the S1 switch or any of the midd...

Page 26: ... middle Trimming potentiometers or trimpots 13 Tunes each note For the OKAY 1 the buttons and potentiometers are soldered onto the same side of the PCB On the OKAY 2 the potentiometers are soldered on the underside Orientation doesn t actually matter but it s helpful to have them all in the same direction A B Output pins The ones on the right side connect to R2 on 555_4040 The left ones are used w...

Page 27: ...ave their pins shorted together as indicated below The remaining third pad is already connected from the PCB s routing and doesn t need to be manually connected or shorted To short the pads apply generous solder to each then solder the middle until the two connect You can do this on either side of the PCB If shorting the pot pads with solder alone is too difficult supplement with a short scrap of ...

Page 28: ...d extend the keyboard s range The OKAY 2 does this for its two octaves Solder the two boards together as indicated It may help to first assemble them into the key cradle for stability Note that the left side of the left board has been trimmed off This allows it to fit snugly into the key cradle Remember to put the trimpots on the opposite side too ...

Page 29: ... in the Adafruit Guide To Excellent Soldering Using a multimeter s voltage meter check that each board is getting power Then refer to the circuit diagrams in the appendix to make sure the power is getting to the appropriate IC pins If the LED light turns on but the two IC boards aren t getting power or working check to see that the bus diodes are in the right direction Check that SPST_VR is acting...

Page 30: ... the 386 input pad marked The right VOL pad connects to board s input Its middle pad goes to the IC s input Its left pad goes to ground The volume potentiometer should match these pads The 386 IC s output and speaker output will have a large voltage square wave If all else fails contact your friendly Oskitone representative Final assembly If all is well and the electronics are working correctly we...

Page 31: ... the fit is too tight carefully trim away excess plastic from the enclosure with a utility knife b Insert LED into its hole on the VOL label c The octave selector rotary switch and volume potentiometer may have tabs that protrude parallel to the shafts These are designed to hold the component in place We won t be using them bend or break them off with pliers d Insert the octave selector rotary swi...

Page 32: ...utton and adjust its pot until the note registers as a high C The pot will have a two or three octave range so just choose the highest C you can accurately get to If you reach the end of the pot s range it will make a small clicking sound but won t be damaged 3 Once that C is set move to the next note on its left This will be B 4 Repeat until you re at the end on the far left You re done Take a se...

Page 33: ...w pushbutton just search for 6x6x6 tactical switch but may find replacing the entire SPST_VR board easier Contact Oskitone for help The OKAY s 3D printed plastic is susceptible to warping under hot temperatures Keep it out of prolonged direct sunlight ...

Page 34: ...Appendix Circuit schematics ...

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