Ok, so hopefully the Thread Title is not misleading.
I am wondering, what is the best way to go about adding an LED to an OUT to show the signal (blinky blinky) as the signal is fluctuating?
Would it just be a resistor from the tip to the LED (+) and then ground the LED(-) on the sleeve?
Hopefully this isnt a ridiculous question haha. But we all know by now that I am full of them 
That’s indeed the way.
TY, that’s what I figured lol.
who knows, maybe the dumb question will help someone in the future as well! 
That would mostly work, but the LED will turn off while the output signal is negative, which could be 50% of the time on some oscillators.
If you care about that situation, you can use a two-colored LED in which the LEDs are connected in parallel but in opposite directions.
that’s even better!!!
Ooh, of course! I even have a few hundred lying around from random projects that I had no idea what to do with. LED’s on all the things!
How dare you, blinky lights are serious business. I remember seeing a neato circuit with two LEDs that blink either one depending on a high vs low. I’ll dig it up when I’m not on my phone (if I remember).
Blinkenlights is so 1970s. The latest buzz is minidrones that signal the synth state through interpretive aerial dance driven by a Markov chain process. May be forbidden in some jurisdictions.
So I have the thing i was lookin for. It’s called an op-amp comparator circuit. It’s pretty specific, and not exclusive to lights blinking obviously, but i just didnt want to leave anyone hanging that was interested.
Not for nothin, but its pretty nifty, although off topic.
@d42kn355, how many lights did you want to blink, how, and is arduino an option?
Oh I am building a Bartons Wave animator with an onboard roland SYS-100 dual LFO and I want all of the jacks to be blinky blinky lolol
This may be a little overkill since I would need 5 - 7 LED’s on the panel, I havent decided if I am just doing 5 jacks or all 7
that would be a lot of transistors to cram behind what is currently already a tight fit haha (eurorack panel - Bartons wave animator and 2 LFO’s - 10hp)
Note that if you add a raw LED to the outputs of your module, the output driver will see a ~1k impedance in parallel with the actual load. This may or may not be a problem, depending on your modules. With a transistor, you’ll instead add a ~100k impedance which is much more on the safe side.
(ignoring voltage drops and transistor base-collector impedance here because not using math is close enough)
Interesting. Noted.
May have to do some re-configuring
I’m flopping around in despair at the thought of using precious milliamps just to drive dumb light emitters. I’ll bet it will look amazing, though.
The answer is to get more milliamps, not use less 
Seriously, though, I think it depends on how visually inclined you are. Blinking lights can give you so much information about the state of your system. Think an indicator for LFO rate. Yeah, you can listen to how fast it oscillates when it’s hooked up, but you can know instantly by just looking at it. Blinking lights for the sake of beauty is a valid choice too, but they do suck the mA’s.
^ this.
Pretty much my exact thing, I REALLY like seeing what the signal is doing.
I am like a freaking moth… lolol blinky blinky lights. bzzt bzzt 
Everybody on this thread is expanding my mind with their ideas. In particular, wouldn’t it be great if we had powered cables that buffered the signal and used their own power to do the flashy blinky thing.
theres that one eurorack module company that is using illuminated jacks. theyre friggin wild.
I can’t for the life of me think of who it is though.
