There are keyboard/sequencer devices like the Arturia Keystep (Pro or OG) that output CV and gate.
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while waiting for a beatstep or other, if you have all the Sam modules built, you can use the LFO to send a signal in the sequencer or in the Envelope (otherwise the mini ADSR has a loop too 
donât need external trigger), a slowly square wave can make a trigger signal too (if you have several VCO)
and a multiple is very useful for multiplying a signal and sending it at the same time in several modules.
and the 8 step sequencer have 8 gate out too
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I meant electrically inverted.
We want current to flow through the MIDI THRU outputs at the same time as is flows through the MIDI IN loop, but when current flows through the 6N137 input LED, its output goes low, the outputs of the inverters go high and no current flows through the MIDI THRU output.
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Good idea to publish that. Following this example, here is mine for euro rack:
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indeed!!! eagle eyes,., for the moment I just changed the 6n138 of the chip to not have to change the footprint on the pcb. Will rectify after I have finished that stuff.
which resistor are you talking about the pull up resistor??
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im a little confused as to what you are angling towards. is this regarding the hex inverter used as the buffer?
that aspect of the circuit works, its been tested in the first prototype as the inverters re invert it.
I took that aspect of the circuit from a midi thru schematic I have in the gameboy megamachine.
unless you are talking about another aspect of it im not too sure. are you talking about the propagation delay of the inverters? as its quite a common midi thru design
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Yeah, the 10k pullup (R19). The output is open drain (i.e. shorting to ground), so the resistor provides all the on current and the signal rise time will depend on the pullup and the input capacitance of the next stage, whatever that is (a quick peek at the ATmega datasheet only says itâs Cpin which is only marginally helpful ).
The datasheet uses 350 ohm for all timing numbers, fwiw, but thatâs probably overdoing things (those specs are ~10Ă better than required by MIDI anyway). Iâve used 2k2 iirc.
EDIT: Found it â itâs max 10 pF, and the MIDI spec says max rise time is 2 us which is about 100Ă the 6N137âs rise time (not 10Ă) measured at 350 ohm/15 pF, so 10k should be safe, even if itâs a bit above the recommendations.
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If it works as is, I must be missing something.
The example in the MIDI 1.0 spec shows a very similar MIDI THRU circuit, but with two inverters.
Is the output of the 6N137 inverted compared to the opto coupler shown in the spec? It doesnât seem to be.
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Yeah, at first I thought there was some cleverness in how the jack pins were connected, but if it is it seems to be too clever for me 
(maybe if I sleep on it)
So the MIDI signal is a 5 mA current loop where a logical 0 is defined as current from DIN pin 4 to DIN pin 5 (or ring to tip for minijacks, which I assume is pin 3 to pin 1 in the LMNC schematics). The opto-coupler is wired to pull the internal signal low when the LED turns on, so is effectively inverting the wire signal to produce the correct logical levels on the âinside,â which makes the ATmega happy.
The MIDI thru/output schematics feeds 5 V to pin 4 and pulls pin 5 low when the internal signal goes low, causing a current to flow from 4 to 5 (or 3 to 1 in the jack scheme).
The LMNC schematics has a single inverter, which pulls pin 1 low when the internal signal goes high, causing a current to flow from pin 3 (5 V via 220 ohm) to pin 1. The TTL inverter has no problem sinking 5 mA, but it looks like itâs sinking when it shouldnât be⌠
I love that spot so much.
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yep im being a dimdimeon @antoine.pasde2 @fredrik . stupid. I see it now. somehow when editing it since the prototype I removed the inverter between the thruâs and the optoisolator.
I realise my error now, I tapped the signal for the atmega after the first inverter initially. realised the error in the circuit on the prototype pcb removed it instead of moving the where the atmega chip was reading it, so yes midi thruâs are wrong. you guys are too good! 
I dont believe I did that very silly
thanks for persisting. yep definitely a silly oversight! why the proto works and this schematic doesnât!
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Iâd point you to this thread, but if we caught this before you got around to order PCBs Iâm not sure it belongs there
(Looks like a very quick fix, given all the spare inverters you have in that chip. A tiny bit of rerouting and youâre done.)
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how about a signed module , Sam Battle signature series ?
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I donât know about anyone else but for me, waking up and firing up the Analog and waiting for the TUBE to warm up before I hear some Buzz, and that fade in sound. yup, love it. I know its got some quirks (BC107 Tubed VCA) but i love mine.
I think this module is a good candidate for PCB in the future ?
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Iâd like to see something like this in Kosmo format. This thingâŚ
Skip to about 5 min. in, for some reason they didnât edit out the fiddling around in the beginning.
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Summary for anyone who doesnât have an hour to spend watching the video?
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Or an effects send/return, Big Muff + Sonic Orb phaser into a wasp filterâŚ
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(no schematics, but PCB has an LM13700, a TL074, two LM386s (!) and a surprising amount of low-distortion opamps for being a distortion unit 
)
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