Triple Function Generator project

is this batch going to be for DIYers only?

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If all goes well, I assume you will eventually order more PCBs so everyone can get in on the fun?

(I’m just assuming the initial batch will go quickly. I know I’m definitely interested.)

yeah, that was the plan.
coming week I’ll be soldering & testing the pcb’s.
I’ll make a separate thread for orders and BOM / buildguide information.


the main focus is DIY. I might consider to offer build modules.

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First test = OK :star_struck:
the pot distance is good. - that is why I have the 5 knobs installed in pic 2.
the switch is a bit close, but not too much. You can solder the ‘default’ setting to the down position.
The PCB is designed to handle the cheaper ‘lug’ type DPDT switch.
You can solder clipped resistor leads into the lugs and holes.
I might search for a DPDT pushbutton solution. tips anyone?

in the mean time, I declare this project “READY”!

note: 20 more sets are ordered


Let’s make the build thread here.

updated BOM 25-07-19

Triple Function Generator BOM version 1 – 2019
Boards: amount
Panel 1
Resistors value total of 3 pcbs
r1, r5, r6, r10, r12, r14 4.99k 18
r2, r16 1k 6
r3 330r 3
r4 100r 3
r7, r8, r11 10k 9
r9 4.2k alternative: 4.32k 3
r13 5.66k alternative: 5.6k or 5.62k 3
r15, r18 499r 6
r17 24k 3
r19 100k 3
d1, d2, d3, d4 1n5711 12
f1, f2 ferrite bead. alternative: 10r 6
c1, c2, c3, c4 100nF 2.5mm ceramic 12
c5, c6 10uF electrolytic 6
u1, u2 8pin socket 6
u1, u2 LM6172 6
Lights, Mids, Darks 10k lin 9mm right angled 9
knobs 9
a, b, c, d DPDT on-on 3
Jacks PJ302M 6
10 pin shrouded header or unshrouded 3
10 pin to 16 pin power cable 3
or use a multicable 1
Normalised inputs
connect pin 1 on pcb1 to pin 2 on pcb2 wire
connect pin 1 on pcb2 to pin 2 on pcb3 wire
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to make this do I just crimp 3 * 10 pin headers along the length of an idc cable??? so a 16 at one end (for the bus board) and then 10 then 10 then a 10 at the other end??? (10s for the modules)

yeah, that is what I meant!

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Exellent thanks Martijn

tip: if you use cheap fake LM6172 ic’s , you get funky blurry outputs!
tip2: Ebay sucks at certain times…

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Hmmm… Do I sense a LM6172 group buy coming on???

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I would get in on that

I could set this up. (with prepayments)
Mouser pricebreaks: (ex VAT)

[1:] € 4,23
[10:] € 3,80
[100:] € 3,11
[250:] € 2,92
[500:] € 2,65
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I’d probably get in on this too.

see here:

I’ve updated the BOM with alternative resistor values and switch info

I just noticed that the pads for normalling the inputs together have (unless I’m mistaken, tried this out with an IDC power socket since it’s what was handy) 2.54mm pitch, so if you solder on right-angle pin headers you could use jumper wires to select how the normals work rather than permanently soldering wires to them. Awesome! I’ll have to order some headers.

yes, idc will work. or dupont pin headers.
You have version 1 on the pcb
1: IN-------- (tip of the input jack)
2: OUT----- (switch of the input jack)
3: GND

connect pin 1 on pcb1 to pin 2 on pcb2
connect pin 1 on pcb2 to pin 2 on pcb3

Version 2 has this:
1: IN-------- (tip of the input jack)
2: OUT----- (switch of the input jack)
3: CHAIN—(tip of the output jack)
This is for routing in series and parallel.

Parallel: (one input source gets routed to all three inputs.)
connect pin 1 on pcb1 to pin 2 on pcb2
connect pin 1 on pcb2 to pin 2 on pcb3

Series: (the output gets routed to the next Function Generator input, three in a row)
connect pin 3 on pcb1 to pin 2 on pcb2
connect pin 3 on pcb2 to pin 2 on pcb3

@csboling: you can still route the boards in series if you would like to. Just wire it from the output jack.
I can make a drawing if you need it.


version 2 schematic.
note: the BOM remains the same. If you want ‘modular’ routing, add pinheaders & cables as needed

my only question would be,
how do you people clean the pcbs?
I use 99% isopropanol and a toothbrush, but at the end it always ends up with a sticky residue.