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R28 

100k 

 

R29 

56k 

 

R30 

1kT 

or thru-hole 

R31 

10k 

 

R32 

15k 

 

R33 

220R 

 

R34 

100k 

 

R35 

47k 

 

R36 

1k 

 

R37 

10k 

 

R38 

39k 

 

R39 

10k 

 

R40 

100k 

 

R41 

180k 

 

R42 

180k 

 

R43 

100k 

 

R44 

10k 

 

R45 

10k 

 

R46 

100k 

 

R47 

150k 

 

R48 

100k 

 

R49 

100k 

 

R50 

100k 

 

R51 

100k 

 

R52 

470k 

 

R53 

2k7 

 

R54 

200k 

 

R55 

2k2 

 

R56 

33k 

 

R57 

27k 

 

R58 

2k2 

 

R59 

33k 

 

R60 

56k 

 

R61 

56k 

 

R62 

100k 

 

R63 

100R 

 

R64 

100R 

 

R65 

62k 

 

R66 

100k 

 

R67 

15k 

 

R68 

100R 

 

R69 

100R 

 

R70 

100k 

 

R71 

150k 

 

R72 

1k 

 

R73 

100k 

 

R74 

8k2 

 

R75 

1k 

 

R76 

470R 

 

R77 

12k 

 

R78 

62k 

 

R79 

2K7 

 

R80 

1K 

 

R81 

1K 

 

R82 

1K 

 

R83 

1K 

 

R84 

470K 

 

R85 

470k 

 

R86 

15k 

 

R87 

330R 

 

R88 

2K7 

 

R89 

1K 

 

R90 

1K 

 

R91 

12k 

 

R92 

100k 

 

R93 

47k 

 

R94 

47k 

 

R95 

1K 

 

R96 

12k 

 

R97 

47k 

 

R98 

30k 

 

R99 

47k 

 

R100 

470R 

 

R101 

470R 

 

R102 

220k 

 

R103 

68k 

 

R104 

10K 

 

R105 

10K 

 

R106 

100k 

 

R107 

330k 

 

R108 

1k 

 

R109 

100k 

 

R110 

47k 

 

R111 

47k* 

 

R112 

10k* 

 

R113 

22k 

 

R114 

220k 

 

R115 

2K2 

 

R116 

1K 

 

R117 

10k 

 

R118 

10k 

 

R119 

10k 

 

R120 

15k 

 

R121 

10k 

 

R122 

15k 

 

R123 

2k2 

 

R124 

47k 

 

R125 

220k 

 

R126 

1k 

 

R127 

100k 

 

R128 

100k 

 

R129 

100k 

 

R130 

100k 

 

R131 

100k 

 

R132 

100k 

 

R133 

1k 

 

R134 

100k 

 

R135 

1k 

 

R136 

1k 

 

R137 

1k 

 

Summary of Contents for Null-A2

Page 1: ...a patch cable into either jack the preset is disconnected a VCO1 pulse out state variable VCF input b VCO2 pulse out ladder VCF input c state variable VCF LP output VCA1 input d ladder VCF output VCA2 input e VCA1 output mixer f VCA2 output mixer g Mixer output headphone amp h ADSR output VCA1 CV input i Clock divider 8 output ADSR gate input j LFO 1 square output S H clock input k LFO2 triangle o...

Page 2: ... are all listed as 10uF these are for decoupling You can replace some of them close to ICs with 100nF if you wish but the ones near the power connector and close to the bottom edge of the PCB should all remain 10uF The LFOs and Sloth have been designed to work with 2 pin bipolar LEDs You can just install normal LEDs instead if you want to be boring The ADSR uses a regular LED RL in the value list ...

Page 3: ...1u C39 1u C40 1u C41 10u C42 10u C43 10u C44 10u C45 10u C46 10u C47 10u C48 10u C49 10u C50 10u C51 10u C52 10u C53 10u C54 10u C55 10u C56 10u C57 10u C58 10u C59 10u C60 10u C61 10u C62 10u C63 10u C64 10u C65 10u C66 10u C67 10u C68 10u C69 10u C70 10u C71 10u C72 10u C73 not on vers 2 C74 10u R1 91k R2 100k R3 100k R4 2M2 R5 24k R6 10k R7 56k R8 1kT or thru hole R9 15k R10 220R R11 100k R12 1...

Page 4: ...R71 150k R72 1k R73 100k R74 8k2 R75 1k R76 470R R77 12k R78 62k R79 2K7 R80 1K R81 1K R82 1K R83 1K R84 470K R85 470k R86 15k R87 330R R88 2K7 R89 1K R90 1K R91 12k R92 100k R93 47k R94 47k R95 1K R96 12k R97 47k R98 30k R99 47k R100 470R R101 470R R102 220k R103 68k R104 10K R105 10K R106 100k R107 330k R108 1k R109 100k R110 47k R111 47k R112 10k R113 22k R114 220k R115 2K2 R116 1K R117 10k R11...

Page 5: ...184 150K R185 56k R186 560K R187 47k R188 15K R189 47k R190 56k R191 22k R192 100k R193 47K R194 33k R195 1M optional see notes R196 1k R197 100k R198 100k R199 RL ADSR LED R200 1k R201 47k R202 330R R203 100k R204 10k R205 330R R206 47k R207 not on vers 2 R208 4M7 R209 330k R210 100k R211 100k R212 220R R213 2k2 R214 4k7 R215 1k R216 100k R217 RL LFO LED R218 2k2 R219 2k2 R220 2k2 R221 2k2 R222 2...

Page 6: ... Trimpot 20k multiturn TR2 TR4 Trimpot 100k TR6 TR7 TR9 Trimpot 50k TR5 Trimpot 1k TR8 BCM847 Q13 Q17 SOT23 6 AKA SOT 457 Mouser Part No 771 BCM847DS115 BC847 Q1 Q3 Q5 Q7 Q8 Q10 Q14 Q15 Q16 Q18 Q20 Q21 Q22 Q23 Q26 Q30 Q32 Q33 Q34 Q37 Q38 Q39 Q40 Q41 Q42 Q43 SOT23 There is no Q25 on vers 2 BC857 Q2 Q4 Q6 Q9 Q19 Q24 Q27 Q28 Q31 Q35 Q36 SOT23 S1JL power diode D6 D7 The ones with the dots near the pow...

Page 7: ...ngle Row Pin Header Strip at least 4 cut into 10 pin lengths Tayda A 197 Passives transistors diodes BOM GET SPARES 470P 1 100n 10 100p 2 10n 4 10u 41 1n 5 1u 8 220n 1 2n2 2 100k 66 100R 4 10k 26 10M 1 12k 5 150k 5 15k 7 180k 2 1k 33 1k Tempco 2 1M 4 200k 1 220k 5 220R 4 22k 5 24k 2 27k 1 2k2 14 2k7 3 2M2 3 30k 3 330k 3 330R 3 33k 4 39k 2 470k 4 470R 7 47k 17 4k7 4 4M7 3 560k 1 56k 6 62k 2 68k 1 6...

Page 8: ......

Page 9: ...Small mod required for R148 ...

Page 10: ... of the outputs is much louder than the other adjust this trimpot to get the outputs balanced TR6 the Freq offset trimpot is used to ensure the Freq pot is functional across its range same idea as the 100k trimpots on the VCOs Ladder VCF TR9 Ladder VCA trimpot at the top of the PCB is used to set up the VCA Plug in a signal and listen to the output Now plug a lead into the VCA CV input with the ot...

Page 11: ...Board close ups Top right ...

Page 12: ...Bottom right ...

Page 13: ...Top middle ...

Page 14: ...bottom middle ...

Page 15: ...Top left ...

Page 16: ...Bottom left ...

Page 17: ...SCHEMATICS ...

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