Hadn’t noticed but you’re right — With switch to the left the Gate Out 1 LED lights up, but it appears on the Gate Out 2 jack, and vice versa. Needs some trace cuts and bodge wires for that.
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I’ve only tested with the MI Module Tester — using the CV output mine responds to 0–+5 V or 0–+2 V square waves (but not 0–+1 V).
But since that’s well below the stated 0.7*V_dd threshold… maybe it varies between different chips.
If that’s the case then maybe there’s a need for the mods after all. I’m leaving the GitLab repo up. I was thinking about unsoldering the pin sockets and putting in DIP sockets for a standard build, but maybe I should leave them and do the modification daughterboards even if I don’t need them.
If you put a gate signal on the gate input it gets ANDed with the gates from the 4051. So then instead of a gate on one of the gate outputs whenever the corresponding stage is active, it’s when the stage is active AND the gate input is high. You could do stuff like send in a high rate gate and then get a ratchet like sequence of gates whenever that stage is high.
If you put a voltage into V in, that sets the upper limit for the CV output. Normally it’s 0 to +12 V but the voltage input rescales that to 0 to whatever.
(Actually not quite that, because the TL074 output swing doesn’t go to +12 V, and there’s a diode drop between there and the CD4051, and there’s another diode drop on the output. I see a maximum CV output of +10 V.)
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OK, looks like:
- The switches are reversed, left position actually sends to SWOUT2 instead of SWOUT1
- R14/R15 and associated LEDs are swapped, R14 is for SWOUT1 but is positioned next to the
Gate Out 2jack and vice versa - The
Gate Outjacks are correctly connected
So what ends up happening is left position sends the gate to Gate Out 2 but lights up the LED next to Gate Out 1.
Easiest fix is to cut the traces to the Gate Out jacks and add bodge wires to reverse their connections. One trace is on each side of the jacks PCB, so you do have to un-install it. Fifth header pad from the bottom should connect to Gate Out 2, fourth from the bottom to Gate Out 1.
(The adjacent pad looks worse in the photo than in real life, but I did clean it up later. Also, you can see how I cut away a bit of the PCB in anticipation of adding the mods. You have to do that carefully to avoid severing the trace to the first jack. Where by “carefully” I mean “more carefully than I did”. Hence the third bodge wire.)
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so you cut 4x traces in total? can you share a picture of where you cut them?
also do you have the LMNC Electric Druid LFOs? does it work for you sending a square LFO into the A/B/C inputs?
No, two traces. One each side. They’re clearly visible leading to those two jacks.
I don’t have that LFO. But even a 0 to +2 V square wave from the MI Module Tester works with mine.
But you have 3 bodge wires?
I think I will just unsolder the pin and heat shrink it to the new wire, saves cutting a track.
Cheers for the heads up though.
The third wire was because I accidentally cut a trace while cutting off a piece of the PCB for the daughterboard.
@analogoutput , has your jack board been cut , top left?
My Module is missing it’s not where I thought it was… had a look arroudn but can’t find it??? Quite Perplexing…
I took another look at the schematics and realized I are dumm and this is not how it works at all. The input voltage doesn’t power the 4051, it goes to the 4051 COM input. Essentially the 4051 is an 8-position rotary switch, connecting COM to one of eight outputs, except it’s controlled by logic inputs. But the chip is always powered by +12 V and my concern about maximum input voltage was misplaced. I thought it was a dodgy idea and it’s not just dodgy, it’s entirely wrong.
So the protection diodes and resistors I added to my daughterboards aren’t needed and in fact may be counterproductive. I don’t see them causing a problem but others whose chips seem to demand higher gate voltages might have trouble. The diodes can be omitted and the resistors can be jumpered. In the updated (untested) design they are removed.
Anyway.
Here’s my Plexquencer.
You can see the two daughterboards. As mentioned above, my chips seem to be quite happy with low gate voltages, so the daughterboards aren’t accomplishing much for me. But they work; they do lower the minimum input voltage that will still produce output gates; and they do correct the flaky behavior previously noted where switching a stage from 1 or 2 to off doesn’t immediately turn off the corresponding gate. And probably they’ll fix it if you have chips that are not as happy with low gate voltages. I haven’t done really thorough testing but the module seems fine.
I have four more pairs for sale. Gerbers, schematics, and design files at the Gitlab repo linked above. Blog post here.
I just finished building two of these kits last weekend. So far I haven’t had any issues with them not triggering, (but I’ve mostly been feeding them from my LFOs and VCOs)
But I’ve got another preplexing mystery, and BOTH of the the modules are doing it.
When I flip the switches to make triggers on 1 or 2, the LEDs for those channels light up exactly how you would expect them to.
…But the jacks that output those triggers are switched. when LED 1 lights up nothing happens on the #1 jack, and the #2 jack goes high.
Same for the other channel #2 LED lights up and the #1 jack goes high
I haven’t taken the time to take them back out of the case and poke at the backs of them yet. I’m guessing it has to have something to do with the components I bought (I like to think I didn’t make the same mistake twice.
I was just wondering if it happed to anyone else…its just so odd…
I may just “fix” it by tweaking the pannel art with a dab of black paint and a silver sharpie.
Yes, that is a known issue, mistakes in the PCB layout, mentioned above in this topic:
In my case I cut traces on the jacks board and added bodge wires to correct it: