#2700 twin t drums

KOSMO MODULES
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BOM for US folks (scroll right to see links) IC was still sourced from UK. Pots and inductor took some sourcing, so maybe order those 1st.
Edit: The .47uf(470nf) caps in my list are huge. Probably should get these box ones instead.

RythmCONTROL
Id Designator Package Quantity Designation Supplier and ref
23 FB1,FB2 Metal Film Resistor 1/4 2 10r 10 OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality
27 R1,R9,R10,R14,R16,R29,R31,R45,R46,R50,R58,R62 Metal Film Resistor 1/4 12 1k 1K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality
33 R23 Metal Film Resistor 1/4 1 2k2 2.2K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality
28 R2,R17,R32,R47 Metal Film Resistor 1/4 4 150k 150K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality
29 R3,R8,R18,R24,R33,R39,R48,R55 Metal Film Resistor 1/4 8 68k 68K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality
30 R4,R5,R19,R20,R34,R35,R51,R52 Metal Film Resistor 1/4 8 10k 10K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality
31 R6,R15,R21,R37,R53 Metal Film Resistor 1/4 5 27k 27K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality
32 R7,R12,R22,R38,R54 Metal Film Resistor 1/4 5 47k 47K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality
34 R25,R41,R42,R56,R59,R60,R61,R11,R13,R26,R43,R40,R44,R63,R64,R65 Metal Film Resistor 1/4 16 100k 100K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality
35 R27,R28,R30 Metal Film Resistor 1/4 3 1M 1M OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality
36 R36 Metal Film Resistor 1/4 1 4k7 4.7K OHM 1/4W 1% Metal Film Resistor
47 R49,R57 Metal Film Resistor 1/4 2 18k 18K OHM 1/4W 1% Metal Film Resistor Royal OHM Top Quality
1 C9,C6 Polyester Capacitor 2 15nf 15nF 0.015uF 100V 5% JFA Mylar Film Capacitors
2 C1,C10,C8,C7,C4 Polyester Capacitor 5 47nf 47nF 0.047uF 100V 5% JFA Mylar Film Capacitors
3 C17,C20 Polyester Capacitor 2 1n5 1.5nF 0.0015uF 100V 5% Mylar Film Capacitors
4 C13,C14 Polyester Capacitor 2 33nf 33nF 0.033uF 100V 5% Mylar Film Capacitors
5 C15,C21,C22,C23,C28 Polyester Capacitor/Ceramic Capacitor 5 470nf 470nF 0.47uF 100V 5% Mylar Film Capacitors
6 C2,C3 Polyester Capacitor 2 150nf 150nF 0.15uF 100V 5% Mylar Film Capacitors
7 C16,C12 Polyester Capacitor 2 10nf 10nF 0.01uF 100V 5% JFA Mylar Film Capacitors
8 C24,C5 Polyester Capacitor 2 100n 100nF 0.1uF 100V 5% Mylar Film Capacitors
9 C11,C18,C19 Polyester Capacitor 1 4.7nf 4.7nF 0.0047uF 100V 5% Mylar Film Capacitors
Capacitors Make them polyester or anything fancy above ceramic
If you end up having to chuck in a couple of ceramics it won’t be the
End of the world, but ceramics may introduce the odd unwanted noise
Here and there, it aint the end of the world but its a bit of a funky one
12 100mh L1 100mh Inductor 1 L 100mH 6x8mm 10% Tolerance Shielded Radial Lead Inductors | eBay or https://www.digikey.com/en/products/detail/RLB1014-104KL/RLB1014-104KL-ND/2561370?itemSeq=365039179
13 Q1,Q2,Q3 2n3904 Transistor 3 2N3904 2N3904 NPN General Propose Transistor
14 U4 Voltage Regulator 1 L78L05_TO92 L78L05ACZ L78L05 78L05 +5 VOLTS 100mA Voltage Regulator IC
15 C25,C26,C27 Electrolytic Capacitor 3 10uf 10uF 50V 105C Radial Electrolytic Capacitor 5x11mm
16 D1,D4,D5,D9,D14,D17 LED_D5.0mm 6 https://www.taydaelectronics.com/catalogsearch/result/?q=5mm+led
17 D2,D3,D6,D7,D10,D11,D12,D13,D15,D16,D18,D19 D_DO-35_SOD27_P7.62mm_Horizontal 12 1n4148 Search results for: '1n4148'
24 J1 PinSocket_1x10_P2.54mm_Vertical 1 MAINBOARDINPUT 40 Pin Male 2.54mm Single Row Pin Header Break away Round Pin Gold Plated
25 J2 PinSocket_1x10_P2.54mm_Vertical 1 MAINBOARDOUTPUT 40 Pin 2.54 mm Single Row Female Pin Header or 10 Pin 2.54 mm Single Row Female Pin Header
26 J3 Multicomp_MC9A12-1034_2x05_P2.54mm_Vertical 1 POWER INPUT 10 Pin Box Header Connector 2.54mm
37 RV1,RV3,RV5,RV7 Alps Potentiomter B470k/ B500k/ even B1M if your funky 4 KICK B470k https://modularaddict.com/parts/potentiometers-3/9mm-round-shaft-6-35mm-vertical-potentiometers B500k
38 RV2,RV4,RV6,RV8 1M Trimpot, 470k is also fine if you can find them 4 1M KTrim 1M OHM TRIMMER POTENTIOMETER CERMET 25 TURNS 3296W
45 U1 DIP-14_W7.62mm_LongPads 1 4011AE CD4011AE RCA INTEGRATED CIRCUIT X5pcs | eBay
4011AE has much better decay to the more modern 4011B. Still plenty of the AE type about, treat yourself :D.
46 U2,U3 DIP-14_W7.62mm_LongPads 2 TL074 TL074 Quad Operational Amplifier J-FET PDIP-14 TL074CN
BIG JACK SOCKETS 12 6.35mm 1/4" Stereo Phone Jack
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Did anyone get around to test a UBE? (that’s the modern version of AE).

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sorry fredrik I missed that in the thread! nice… learnt something new I didn’t realise they offered modern and unbuffered. I have ordered some and when they turn up ill pop one in and I will let you know

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thanks riggidyboo I will share a link to this on the main page!

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Well, ordered a couple off these and some dual vcas. Looking forward to adding some more modules.

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Ok so the 4011UBE 's turned up that @fredrik asked to test.

yes they do work however they do have more decay. If you drop the 4011UBE into the circuit as it is, the decay knob on max would cause the drums to oscillate, so in order for it to still be controllable to your liking with the preset potentiometers may I suggest to swap

R2 150k
R17 150k
R32 150k
R47 150k

with a higher resistance, I think the best bet is 470k which will give the preset potentiometer plenty of travel for you to adjust the decay knob to your liking.

I will make sure to drop these resistors in to double check for myself later on today.

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100% have shipped mine … the 4011’s have turned up . need to check the rest of the BOM.

Twin T’s Twin T drums comming shortly :wink:

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good to know! I have footage of building it I will have it commentated within the next few days, the only thing I suggest build notes wise if you tackle it before is solder the 3 resistors on the front of the control pcb first. this project got pretty busy so some resistors are on the front, you’ll know which as the footprints are on the other side

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just built mine and all ok except the lights. They work fine if I plug a lfo in, but they dont light up if I use my beatstep. Any ideas anyone? Thanks, Beau

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If I’m reading the schematics correctly, the input LEDs just shows the input level with no pulse stretching, so it could just be that the pulses are too short to notice.

(no idea what the beatstep is using, but synth triggers tend to be 1-5 ms or so, which may not be noticeable)

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@lookmumnocomputer 2700 BOM says Qty 1 for 4.7nf cap, but there is 3.

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aha thanks for that riggidyboo

EDIT ITS NOW FIXED CHEEERZZZ

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yes to backup what fredrik is saying, the led is just mirroring the trigger inputs. interesting they don’t light up for your beat step. as the beat step standard gate is still wide enough to see. in the ones I built I tested it and was happy enough with the LED’s even on short triggers. however this may be because I use super bright LED’s I did not think to try dimmer LED’s with it. ill have a look and see if just piggybacking some capacitors might solve your problem let me give it a go.

but @beau is it sounding alright? glad it is actually working!

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yeah it works fine Sam. It lights up if I plug an LFO into it, just not the beatstep

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Thonk quoting 3 weeks for delivery :frowning: hope is just old info. Order the POTS anyway.

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Just finished one. Definitely one of the more complex builds. Made a terrible loud whining noise when I plugged it in, but I figured all the trimpots needed adjustment. I adjusted each drum sound down until there was no whine, and now everything souds great as it should. Nice work @lookmumnocomputer.

Also, an exacto knife works good in a pinch, when you have lost your only micro flathead screwdriver.

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Thonk Delivered today. Just waiting on the PolyCaps now

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I was just looking over the BOM, and I noticed Sam’s note for the decay pots : “Alps Potentiomter B470k/ B500k/ even B1M if your funky”

What exactly does “Funky” mean in this context? I like to think I’m a funky guy, so my fist impulse is to go with 1M pots.

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it would just mean more decay to the point it would self oscillate on the extreme of the pot if you have it calibrated to do so. I went for 500k because im not so funky! just because I didn’t want to accidentally leave it on self oscillate then look around going “what the fudge did I do!”

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