SVCO-B Issue 2 Builder`s Guide
Contents
1. 1 5 kilohms For capacitors luF one microfarad 1000nF one thousand nanofarad To prevent loss of the small as the decimal point a convention of inserting the unit in its place is used eg 4R7 is a 4 7 ohm 4K7 is a 4700 ohm resistor 6n8 is a 6 8 nF capacitor Slim VCO issue 2 Parts List Resistors 1 0 25W or 0 4W metal film resistors are recommended Not all resistor spaces are filled up These are for use with the expansion port For the standard SVCO B module R18 R30 R39 R42 R63 and R65 should be left empty 1K R41 R4 2K2 R38 3K6 R37 3K9 R44 7K5 R6 9K1 R3 10K R32 R60 R46 R47 15K R5 R64 R62 R59 R61 22K R19 R35 R40 R50 R51 R22 R20 27K R10 30K R7 39K R26 R9 R34 ATK RO R2 R21 R23 R43 68K R15 75K R8 R31 R28 100K R13 R71 R16 R68 R29 R48 R24 R57 R69 R55 R67 R66 R58 R54 R52 R53 R56 R70 R17 R1 R11 150K R36 220K R49 300K R25 680K R14 1M R27 R33 R45 Oakley MOTM systems 120K R12 Synthesizers com systems 180K R12 1K 1 KRL temp co PTC mounted on top and in contact with U6 Capacitors 100nF axial ceramic C16 C4 C6 C1 C8 C7 C5 C18 C3 C11 C19 C9 C17 C2 4p7 COG 2 5mm ceramic C12 100pF COG 2 5mm ceramic C15 150pF COG 2 5mm ceramic C13 470pF COG 2 5mm ceramic C10 InF COG 2 5mm ceramic C14 2u2 35V electrolytic C20 C21 Alternatively 50V or 63V radial polystyrene can be used but these tend to be much larger devices2. Apply power to the unit making sure you are applying the power correctly Check that no device on the SVCO main board is running hot Any sign of smoke or strange smells turn off the power immediately and recheck the polarity of the power supply the two transistors Q4 and Q5 the direction of the ICs in their sockets and the polarity of the electrolytic capacitors Now you need to check the outputs of the VCO are working The module has two outputs a pulse wave and a sawtooth wave The pulse wave output should generate rectangular wave shapes that move between approximately 5V and 5V Check that with the waveshape pot at its lowest setting the pulse output is around 5V Now move the waveshape pot to its maximum setting the pulse output should now be around 5V Now connect the pulse output to your monitoring system If you haven t built a modular VCO before you should note that the output level is much higher than ordinary audio signals Turn the waveshape pot to its middle position You may hear a tone but you may just hear a series of clicks Make sure that the tune pot controls the pitch of the tone or the repetition rate of the clicks Insert a CV from your midi CV convertor or sequencer Check that a rising control voltage increases the pitch of the SVCO It will probably not play in tune since it will need proper calibration to do that Now unplug the note CV input and plug it into the CV IN socket Check that the pitch increases when
3. and so on Power Location number Schematic Pin number 15V Missing Pin 5V Module GND 15V Not connected 1 NNnBWN aA BW NWN 5V is not used on this module so location 3 pin 2 is not actually connected to anything on the PCB If fitting the PWR header you will also need to link out pins 2 and 3 of PSU This connects the panel ground with the module ground Simply solder a solid wire hoop made from a resistor lead clipping to join the middle two pads of PSU together 16 Building the SVCO B module using the Sock6 board This is the simplest way of connecting all the sockets to the main board The Sock6 board should be populated in the way described in our construction guide found on the project webpage There are only two headers UPR for upper which is eight way and LWR for lower which is four way Both headers are fitted to the bottom side of the board The wire link L1 should not be fitted to the Sock6 board You need to make up two interconnects The eight way one should be made so that it is 95mm long The four way should be made to be 110mm The SVCO A_ prototype module showing the detail of the board to board interconnect The SVCO B would be identical to this Here I have used the Molex KK 0 1 system to connect the Sock6 to the main Slim VCO PCB Note also the black jumper on pins 1 and 2 of the BUSS connector This shorts out the 1V octave input to ground when no jack plug is inserted thus reducing
4. and the octave board is 86mm deep 93mm high The Octave board sits above the main board on three 25mm hex threaded spacers The Slim VCO board has been laid out to accept connection to our Sock6 socket board This small board speeds up the wiring of the six sockets and reduces the chances of building mistakes The 10 way IDC interconnect carries signals and power between the octave board and the main board You can also see the side adjustable trimmers on the main board SVCO B Parts Lists Note that this is the parts list for the SVCO B module and not the SVCO A The simpler A version has its own Builder s Guide and this should be used if you are building the A version The SVCO B module is made from two PCBs the main board and the daughter board The proper name for the main board is Slim VCO and the daughter board Slim VCO Octave Board Issue 1 Octave boards are designed to sit above issue 1 1 or 2 Slim VCO boards The earlier issue 1 Slim VCO boards cannot be used with the Octave boards For general information regarding where to get parts and suggested part numbers please see our useful Parts Guide at the project web page or http www oakleysound com parts pdf The components are grouped into values the order of the component names is of no particular consequence A quick note on European part descriptions R is shorthand for ohm K is shorthand for kilo ohm R is shorthand for ohm So 22R is 22 ohm 1K5 is 1 500 ohms or
5. plus return postage costs If you have a comment about this builder s guide or have a found a mistake in it then please do let me know But please do not contact me or Paul Darlow directly with questions about sourcing components or general fault finding Honestly we would love to help but we do not have the time to help everyone individually by e mail Last but not least can I say a big thank you to all of you who helped and inspired me Thanks especially to all those nice people on the Synth diy and Analogue Heaven mailing lists and those at Muffwiggler com Tony Allgood at Oakley Sound Cumbria UK March 2014 updated January 2015 No part of this document may be copied by whatever means without my permission 21
6. strand wire This keeps the connection firmly in place and very neat I normally bend the wire at one end into a hook and place the straight end into the PCB pad s hole I then loop the hooked end around the switch tang and squash the hook into place with a pair of needle nose pliers before soldering it The solder pad on the board can then be soldered from the topside and if necessary the excess wire can be carefully snipped off from underneath 15 Connections Power connections MOTM and Oakley The PSU power socket is 0 156 Molex MTA 4 way header Friction lock types are recommended This system is compatible with MOTM systems Power Pin number 15V 1 Module GND 2 Earth PAN 3 15V 4 Pin 1 on the I O header has been provided to allow the ground tags of the jack sockets to be connected to the powers supply ground without using the module s OV supply Earth loops cannot occur through patch leads this way although screening is maintained Of course this can only work if all your modules follow this principle It s worth filling the empty holes of the PWR pads with solder Power connections Synthesizers com The PWR power socket is to be fitted if you are using the module with a Synthesizers com system In this case you should not fit the PSU header The PWR header is a six way 0 1 MTA but with the pin that is in location 2 removed In this way location 3 is actually pin 2 on my schematic location 4 is actually pin 3
7. unwanted noise pick up 17 Hand wiring the sockets If you have bought Switchcraft 112A sockets you will see that they have three connections One is the earth or ground tag One is the signal tag which will be connected to the tip of the jack plug when it is inserted The third tag is the normalised tag or NC normally closed tag The NC tag is internally connected to the signal tag when a jack is not connected This connection is automatically broken when you insert a jack Once fitted to the front panel the ground tags of each socket can be all connected together with solid wire I use 0 91mm diameter tinned copper wire for this job It is nice and stiff so retains its shape A single piece of insulated wire can then be used to connect those connected earth tags to pin 1 of LWR Pin 1 is the square solder pad All the other connections are connected to the signal or NC lugs of the sockets The tables below show the connections you need to make UPR Pin Pad name Socket Lug Type Pin 1 Module ground CV IN NC Pin2 CV1_IN CV IN Signal Pin3 Module ground SHAPE CV NC Pin4 SHAPE CV SHAPE CV Signal Pin5 Module ground SYNC NC Pin6 SYNC IN SYNC Signal Pin7 BUSS CV 1V OCT NC Pin8 KEY CV 1V OCT Signal LWR Pin Pad name Socket Lug Type Pin Panel ground Connects to all sockets Ground lugs Pin2 RAMP OUT SAW TRI Signal Pin3 Not used Pin4 PULSE OUT PULSE Signal 18 Testing the SVCO B Remove the 10 way ribbon cable temporarily
8. you turn up the CV in pot Now listen to the output of the saw tri output with the note CV connected back into the 1V OCT again If you have an oscilloscope then it s worth having a look at the output waveform here Watch what happens as you turn the waveshape pot from 0 to 100 The output should move from a rising ramp waveform to a falling sawtooth via a triangle wave in the middle The sawtooth and ramp waves should go from approximately 5V to 5V and the triangle only 2 5V to 2 5V As you turn the waveshape pot the sound should change from bright and brassy at either end to a quieter and smoother sound in the middle Both the saw and ramp waves actually sound the same even though one is actually the mirror image of the other Power down the module and refit the ribbon cable Re apply the power and check the octave board for any smells and other untoward things You should notice the orange LO LED glowing nicely If not you have a problem The SVCO B should always power up in the LFO mode Now flick the octave switch up and the 32 LED should come on and the LO one go out Make sure you can go up and down the LED with the INC DEC switch Note that you can t scroll round and round Once you reach the top of the ladder it will stay there until you use DEC Likewise you can t get from LO to 2 without going back up again 19 If you have been listening to the SVCO s output while using the INC DEC switch you will have heard the pitch cha
9. Oakley Sound Systems SU Oakley Modular Series Slim VCO B SVCO issue 2 amp Octave Board issue 1 Builder s Guide V2 0 2 Tony Allgood Oakley Sound Systems CARLISLE United Kingdom Introduction This is the Project Builder s Guide for the Slim Voltage Controlled Oscillator variant B SVCO B 5U module from Oakley Sound This document is to be used with issue 2 main boards and issue 1 octave boards In this document you will find a basic introduction to the board a full parts list for the components needed to populate both boards and a list of the various interconnections For the User Manual which contains an overview of the operation of the unit and the calibration procedure please visit the main project webpage at http www oakleysound com s vco htm Also on the SVCO webpage is all the documentation for the SVCO A variant The A version is similar to the B version but lacks the octave and LFO switching For general information regarding where to get parts and suggested part numbers please see our useful Parts Guide at the project webpage or http www oakleysound com parts pdf For general information on how to build our modules including circuit board population mounting front panel components and making up board interconnects please see our generic Construction Guide at the project webpage or http www oakleysound com construct pdf pA p W5 tie iaaa 3 3 i R e T ah P iQ apeere E p s 4
10. The first ever SVCO B fitted behind a natural finish Schaeffer panel This is an issue 1 1 SVCO main board and issue I Octave Board The issue 2 Slim VCO amp issue 1 Octave Board On the SVCO printed circuit board I have provided space for the four main control pots If you use the specified 16mm Alpha pots and matching brackets the PCB can be held very firmly to the panel without any additional mounting procedures The pot spacing on this board is different to many of our other 5U modules instead of 1 625 it is 1 375 Used in conjunction with smaller 20mm diameter knobs this still allows for an attractive module design and finger friendly tweaking The design requires plus and minus 15V supplies The power supply should be adequately regulated The current consumption for the whole SVCO B module is about 47mA and 38mA Power is routed onto the main PCB by either our standard four way 0 156 MTA156 type connector or the special five way Synthesizers com MTA100 header The octave board takes its power directly from the main SVCO board via a 10 way ribbon cable This ribbon cable also carries the reference voltage used by the octave board the wiper voltage from the frequency pot and a voltage that controls the pitch of the SVCO The main PCB has four mounting holes for M3 bolts one near each corner These are not required for panel mounting if you are using the three 16mm pot brackets The main board size is 109mm deep x 123mm high
11. at would probably clash is another SVCO B Building the Oakley SVCO B Once the PCBs have been populated the module I recommend that the module be assembled in the following order 1 Fit main PCB to front panel using the pot nuts and washers 2 Solder the Frequency potentiometer See next section for help with this 3 Fit the 25mm hex spacers to the main board 4 Fit the LEDs and octave board as described later in this document 5 Wire the switch to the octave board 6 Attach the socket board to the panel 7 Fit interconnections 8 Test and calibrate 11 Wiring the Frequency Pot The Frequency pot called TUNE on the SVCO PCB is mounted differently to the other pots on the SVCO B This is because to make room for the octave board the main board has to be moved down a few millimetres This means it needs to be wired into the board with some short lengths of solid core wire It is recommended that this be done without the octave board in place How you will solder this pot will be down to personal preference but if you have used a pot with standard solder tags you may wish to solder the wires onto the pot tags first and then feed the little stumps of wire through the holes of the unmounted PCB Then with the frequency pot still loose attach the PCB to the front panel with the other three pots Once the board is in place and at exactly ninety degrees to the front panel you can then solder the little bits of wire from the un
12. derside of the main board Alternatively you may wish the mount the main board before doing anything to the frequency pot The pot can then be soldered with solid core wire with the main board in place Small lengths of wire with a little hook on one end can be fed through the solder tags of the pot and into the main board The hook can then be soldered onto the pot s lugs The module can then be flipped over and the leads soldered and cut as normal 12 Fitting the LEDs and the two boards together All six LEDs neatly fitted to the front panel No additional fixing or LED clips are required The Octave board is mounted on three 25mm hex threaded spacers so that it sits safely above the Slim VCO board You may be able to use slightly smaller spacers but you do need to ensure that the LED legs on the underside of the board do not touch the top of the two middle pots I use shakeproof washers in between the screw heads and the PCBs You can just see the washer underneath the head of the screw in the photograph and a similar one is used at the other end of the spacer that attaches the SVCO board There is some degree of slop in the oversized mounting holes on both PCBs This should give you enough wiggle room to allow the LEDs to be squeezed into the holes in the front panel without too much hassle However the LEDs should be preformed before trying to fit the two boards together LEDs must be fitted the right way around otherwise they wi
13. ed either on the Sock6 board or on panel One 27mm knobs and three 20mm knobs Two 2 x 5 10 way 0 1 IDC female box connector Three 25mm M3 hex threaded spacers Six M3 nuts and shakeproof washers Six 12mm M3 machine screws A very small length of 10 way 0 05 IDC cable You can cut down larger width to make 10 way if you need to A small amount of thermally conducting paste can be useful to help bond the PTC and U6 together Around 2m of insulated multistrand hook up wire for the socket connections Thin solid core wire for the frequency TUNE pot and switch connections Components required if using optional Sock6 board Molex MTA 0 1 header 8 way UPR Molex MTA 0 1 housing 8 way UPR Molex MTA 0 1 header 4 way LWR Molex MTA 0 1 housing 4 way LWR 112APC Switchcraft 1 4 socket SK1 SK2 SK3 SK4 SK5 SK6 L1 on the Sock6 PCB is not to be fitted If using Molex KK you ll also need at least 24 crimp terminals Suitable lengths of wire to make up the two interconnects and four cable ties The 10 way IDC insulation displacement cable interconnect that connects the two boards Use a bench vice to clamp the connectors onto the ribbon cable Ensure that the connectors are fitted the right way so that pin 1 goes to pin 1 ME SP th Ss A SPP ea rages aa ol Oll aie wW amp Enun Oba 6E O _ 9 EL Aby BPP OAO i YD A close up of the VCO core on the SVCO main board Note the positioning of the pos
14. file C1 C10 C11 C12 C13 C14 C15 C16 C17 C4 C5 C2 C3 C18 C6 C7 C8 10u 35V electrolytic low profile C9 Discrete Semiconductors 1N4148 signal diode D2 D3 D4 D5 D7 D8 BAT 42 schottky diode D1 D6 3mm green LED 2 4 8 16 32 3mm orange LED LO You can use any colour LEDs you like But if you really have to use blue ones then you ll probably need to increase the value of R9 to reduce the current and therefore the brightness Integrated Circuits 74HC14 hex schmitt trigger U 74HC138 decoder U 74HC192 up down counter U DG408 to 8 analogue switch U U U U BRON FR WwW 78L05 100mA 5V regulator TLO72CN dual FET op amp LT1013CP dual precision op amp nN N IC sockets are to be recommended You need two 8 pin one 14 pin and three 16 pin DIL socket Trimmer resistors All are multiturn cermet types with the usual top adjustment screws 5K OCT2 100K LOF Miscellaneous 2 x 5 way 0 1 box header SVCO_BRD Switch One single pole ON mom OFF ON mom toggle switch is required for the octave selection These are the type that are spring loaded so that the toggle naturally sits in the middle position The switch will not stay in the up or down position and because of this they are called momentary switches The switch is mounted on panel and wired to the octave board with very short fly wires see later for details Other Parts Required Six Switchcraft 112APCX 1 4 sockets mount
15. iring Miscellaneous Leaded axial ferrite beads L1 L2 2 x 5 way 0 1 box header OCTAVE_BRD MTA156 4 way header PSU Oakley MOTM power supply MTA100 6 way header PWR Synthesizers com power supply Molex MTA 0 1 header 3 way BUSS for connecting to Oakley CV gate buss Molex MTA 0 1 header 8 way Molex MTA 0 1 housing 8 way Molex MTA 0 1 header 4 way Molex MTA 0 1 housing 4 way UPR for connecting to sockets UPR for connecting to sockets LWR for connecting to sockets LWR for connecting to sockets If not connecting to the Oakley Buss then you will also need a 0 1 jumper to short out pins 1 and 2 on the BUSS header If you are going to be using the Oakley Buss you will need the usual 3 way KK MTA housings for your connecting cable See section on the Oakley Buss in the User Manual for the SVCO Slim VCO Octave Board issue 1 Parts List Resistors 1 0 25W or 0 4W metal film resistors are recommended However the four 6K8 resistors must be 0 1 0 4W metal film or better 100R R10 1K R9 6K8 0 1 R15 R17 R21 R22 10K R1 R4 20K R19 22K R11 R12 R20 47K R14 R16 R23 75K R13 100K R5 R6 R7 R8 R24 220K R2 R3 Oakley MOTM systems 270K R18 Synthesizers com systems 100K R18 Capacitors 100nF axial ceramic InF 63V polyester film box 100nF 63V polyester film box luF 35V electrolytic low profile 2u2 35V electrolytic low profile 4u7 16V electrolytic low pro
16. itive temperature coefficient PTC resistor The PTC straddles U6 and a small amount of thermal paste can be used to keep them both at the same temperature Note also C14 In this prototype I have used a radial polystyrene capacitor Although this one fits just fine a much smaller COG ceramic capacitor would have been neater 10 An important note about mounting the pots Normally it doesn t matter too much whether the PCB is mounted exactly at right angles to the front panel on an Oakley module However for the SVCO B you need to be more careful The SVCO B uses two PCBs and that takes up more room This means there is not so much room between the octave board s components and the PCB or its mounting plate in any module mounted to the right of the SVCO B in your modular The highest point on the octave board is the top surface of the IDC socket Now the front panel has been designed so that this should not clash with any adjacent module However it is very close So by ensuring that the main board is mounted as close as possible to exactly ninety degrees will mean that the IDC socket does not bump into anything it shouldn t So don t solder those pot brackets until you have verified that the main SVCO PCB is sitting at right angles to the front panel It should be noted that most modules PCBs are not mounted right alongside the left hand edge of a module Indeed even if you really badly skewed the SVCO PCB mounting the only module th
17. ll not light up Removing an erroneously fitted LED will be awkward once the switch is fitted The cathode of the LED is fitted towards the top of the board for all six LEDs If you are using the Scheaffer panel design on the website then you need to preform the LEDs in the following way Bend at right angles the LEDs legs 2mm from the base of the body 13 Now trim the leg length so that the distance between the bend and the end of each leg is 10mm Now fit each LED into its PCB location but don t solder them just yet Now position the octave board against the front panel You ll have to take your time here as all the LEDs will have to be gently coaxed into their panel holes Now using three M3 screws and washers fit the octave board to the three hex spacers Gently position the LEDs in place again making sure that the LEDs leads do not touch the front panel itself Solder from the topside of the PCB one leg of each LED Reposition any LED that may have moved and then solder the other leg Using a 3mm thick panel the domed top of the LEDs just sit proud of the panel surface giving a neat appearance 14 Wiring the Switch The switch should be wired to the Slim VCO Octave Board and not the main Slim VCO PCB The pads marked OCTAVE on the SVCO main board should be left empty and unconnected You should wire the switch to the octave board as you would other Oakley modules I typically use solid core wire rather than insulated multi
18. nging It is unlikely that the pitch will change in perfect octaves at the moment but each step change should be pretty dramatic The biggest change in pitch will probably be at the LO setting And in this setting the range of the frequency pot will be considerably more than in the other settings Check that in the LO mode you can sweep over a very large range You may wish to patch your SVCO to modulate another module perhaps the pitch of another VCO to test this Remember that the SVCO will produce some very slow changes in output at lowest frequencies If all this happens the chances are that you have a working module and it is now time to calibrate The User Manual gives full details on how to calibrate your module 20 Final Comments If you have any problems with the module an excellent source of support is the Oakley Sound Forum at Muffwiggler com Paul Darlow and I are on this group as well as many other users and builders of Oakley modules If you can t get your project to work then Oakley Sound Systems are able to offer a get you working service If you wish to take up this service please e mail me Tony Allgood at my contact e mail address found on the website I can service either fully populated PCBs or whole modules You will be charged for all postage costs any parts used and my time at 25GBP per hour Most faults can be found and fixed within one hour and I normally return modules within a week The minimum charge is 25GBP
19. so do check that it will fit Discrete Semiconductors 1N4148 signal diode D3 D4 D5 D6 D7 D8 D9 5V6 zener diode D1 D2 2SK30A GR Japanese JFET Q3 BC550 NPN small signal transistor Q1 Q2 Q4 BC560 PNP small signal transistor Q5 Integrated Circuits THAT300 NPN array U6 CA3130EZ single MOSFET op amp U7 U8 TLO72CN dual FET op amp U5 TL074CN quad FET op amp U4 U9 LM4040DIZ 10 0 10V reference U1 LT1013CP dual precision op amp U2 U3 The LM4040CIZ 10 0 is also suitable IC sockets are to be recommended You need five 8 pin and three 14 pin DIL sockets Trimmers preset resistors All are multiturn cermet types with side adjustment screws Note this is different than most Oakley modules which use top adjustment screws On this module because of the placement of the octave board you must be able to have access the screws from the side of the module That is fit the screws so that they face towards the top of the board 10K HFT SCL 100K TUN 20K OCT Potentiometers Pots Alpha 16mm PCB mounted types 47K or 50K linear EXPO_CV SHAPE SHAPE CV Alpha 16mm panel mounted with solder tag of type 47K or 50K linear TUNE Not soldered directly to the PCB See later Three 16mm pot brackets All four pots can be PCB mounted types if this is all you can get However since the TUNE pot will be mounted slightly above the board then it may be preferable to use a pot with a solder tag connection to allow for simpler w
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