Allow to connect linear or microphone lever sources to the microrack.
- optional pull-up to connect electrect microphone or some non-audio sources like sustain pedal that acts like a switch.
- optional DC block feature
- gain control, from -10 to +20 dB
- signal level indicator
Image of the latest released version of the module. This is not the final product, development is in progress.
Known issues:
- pull-up is needed
- dc block switch is needed
- gain control knob is needed
- 3-led signal level indicator is needed
- update pcb color marking is needed
- rotate breadboard header for a tighter fit is needed
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Module description was updated!
Hmm, what if this one could double as an expression pedal input, or it would be an overcomplication?
From one side it would be cool, and basic schematic is kinda simple, but on other hand, as it would require sending actual voltage to the jack, it might be dangerous if connected to an audio device while in “expression pedal” mode. So maybe dedicated module with a big red
scary sign “expression pedal only” is better.
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That’s what I mean when add pull-up feature: to connect sustain and expression pedals.
It is interesting expression pedals „is powered” by ring contact.
But if you leave ring open and pull-up tip to 5V, it still will work (with pull-up resistor as high side of the voltage divider).
If pull-up resistor will be about 10k, it wouldn’t damage any audio device. And almost all audio outputs has output capacitor to block DC.
One another thing about expression pedals to mention.
I hope you are aware that these pedals might have different polarity. It took me some time to recall it myself.
They might have a switch to choose, but some do not.
P.S. If you do not have an expression pedal for tests, I can lend mine to you for experiments. My pedal has switchable polarities, so both variants could be tried.
I guess if we add pull-up to both channels — tip and ring — any expression pedal configuration will be possible
Here is new version draft, with pullup and DC block feature and variable gain.
(maybe input gain will be up to +60 dB)
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