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Post by pt3r on Oct 27, 2021 11:19:33 GMT
When designing a module do you make sure that outputs can only send voltages out, just in case someone accidentally patches a CV into the output of your module.
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Post by admin on Oct 27, 2021 11:32:11 GMT
I'm not a module designer, but I would say that it depends what your module does and whether your output is always an output or can also be used as an input. For an oscillator or filter for instance it makes sense to protect the output, because it makes absolutely no sense to send voltage into it. A weird and super interesting example of where the line blurs is the 3vcswitch where the two inputs can be outputs and the one output can be an input and the whole flow can work in reverse. wiki.aemodular.com/pmwiki.php/AeManual/3VCSWITCH |
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Post by robertlanger on Oct 27, 2021 12:24:35 GMT
In general, almost all AE modules have a 1k resistor in each output line; this avoids "hard" shorts / maybe damaging an OpAmp output. And when e.g. connecting two outputs, this resistors do some kind of crude mixing, which is also fine IMO.
Only with precision 1V/octave outputs, I use no or a very small resistor, because here a 1k would cause unwanted voltage drops. I've never heard (in the AE world) of a case where an output got destroyed by feeding in a voltage.
Funny story: Some time ago, I patched accidentally an LFO to a filter output, resulting in a kind of nice sounding sidechain-pumping effect... I think modular synths is the only field where stuff like this is "allowed" 😅
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Post by pt3r on Oct 27, 2021 12:50:31 GMT
I see, I put diodes on each of my outputs hoping those would block input voltages, is that a bad design?
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pol
Wiki Editors
Posts: 1,277
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Post by pol on Oct 27, 2021 19:44:47 GMT
In general, almost all AE modules have a 1k resistor in each output line; this avoids "hard" shorts / maybe damaging an OpAmp output. And when e.g. connecting two outputs, this resistors do some kind of crude mixing, which is also fine IMO. I can confirm this mixing does happen, I found out by accident! |
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Post by keurslagerkurt on Oct 29, 2021 14:14:09 GMT
I see, I put diodes on each of my outputs hoping those would block input voltages, is that a bad design? This is only good when your outputs are digital signals (eg triggers, or +5V/gnd). In case of audio out this will usually not work!! (because audio is AC, the diode distorts the signal). In general, diodes in your audio chain are only good if you really want clipping/distortion/ladder filter effects. Not for clean audio. But I suppose this is about your AEclidiaen module, in which case I think it will work just fine. Also, considering AE only runs on 5V, the diode drop of 0.7V can be tricky to deal with. I think most envelopes will accept a 4.3V trigger/gate instead of 5V, but I still believe the closer to 5V the better. For my own modules, I myself looked up the MCP602/4 maximum current output & power, and calculated that if you put in a 220 ohm resistor (1/4W) at the output, you should be fine. The maximum current when you would short the module to ground, would be 5V/220 = 22.7 mA. This is fine for the MCP opamps. Best is to look up the datasheet of your output stage IC and decide according to its max ratings. I think for example that CD40xx logic IC's can provide less amps than the MCP opamps, in which case a larger resistor would be needed. |
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Post by enslavedelectron69 on Feb 24, 2022 2:43:36 GMT
Diodes are great for stopping power going the wrong way from say a capacitor that's discharging 12v + onto 12v - lines as the modules are now getting quite sophisticated and it's not toy town synth land anymore its proper stuff and iv not looked at my eurorack for a week I'm hooked and since its breadboard and arduino friendly there's no worries about porting over designs it's only gonna get better...dive in
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Post by rappel on Sept 2, 2022 9:39:43 GMT
For MidiMuso 12 CV DIY kit, it's suggested to add diodes protections to each and very output. Thonk is seeling an assembled version, but it doesn't say if outputs have protection or not. www.thonk.co.uk/shop/cv-ocd/ |
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