Author Topic: How to install an on/off Speed indicator light on Neovibe?  (Read 1848 times)


How to install an on/off Speed indicator light on Neovibe?
« on: March 17, 2013, 01:27:40 PM »
Hey Folks, I'm working up on putting together the Neovibe Circuit, PCB from General Guitar Gadgets, Link Here:

With a schematic found here:

I'm also putting the circuit into a Crybaby Wah Pedal shell to control the speed off the foot controller. I've got the PCB almost all populated, just need to find a good AC Adaptor and Diode bridge in order to finish the power supply. While I'm waiting for those to come my way I've been trying to look into how to wire up an LED under the foot controller to double as an on/off indicator that tracks the LFO controlling the internal lamp. I think having a pulsing Blue LED coming from inside the Pedal will look awesome as F*** on stage, and totally compliment the overall trippiness the Univibe effect already has.

I'm mostly concerned with how and where to take the oscillating signal from to drive the LED, and what kind of buffer I should use. I don't want to mess up the action of the oscillator or the lamp by accidentally stealing voltage or current from where it should otherwise go!

I don't have any Schematic drawing software, so I'll just try and type this idea out. I'm thinking I'll take a wire from the wiper of the Depth pot, go through a 10 uF cap and 10kΩ resistor to the gate of a JFET, probably a J201 because I have a bunch lying around. The FET would have the gate connected to ground through a 1MΩ resistor, the drain hooked to the +15v supply through a 2kΩ resistor, and the source wired through an LED to ground. The On/Off Switching would be through the 3PDT Footswitch I have and I'd just switch in and out the LED's connection to Ground through the switch.

I haven't had much chance yet to research the specs on this idea, but does the forum think I have it close? If there's a simpler and/or more efficient way of accomplishing this task, or some design aspect that I'm missing here, I would love to know! Thanks for checking it out, and for any responses that come in. PEACE!


Re: How to install an on/off Speed indicator light on Neovibe?
« Reply #1 on: March 17, 2013, 04:28:24 PM »
Give a read to "UVICS" (Uni-Vibe In a Crybaby Shell) and "Son of UVICS" at geofex. One method is shown in some detail, putting an LED paralleled by a resistor in series with the lamp. You can put an LED+resistor in parallel with the lamp, but this eats way more current.

There are others, but the LED+resistor in series with the lamp is pretty fast and easy on a stock unit.

In response to the questions in the forum - PCB Layout for Musical Effects is available from The Book Patch. Search "PCB Layout" and it ought to appear.


Re: How to install an on/off Speed indicator light on Neovibe?
« Reply #2 on: March 17, 2013, 06:37:02 PM »
HA! Seriously? That's one of those solutions that is just too simple for me to even think of. I suppose Occam's Razor has done it again... :icon_rolleyes: In that case, I suppose to make that double as an on/off indicator, I can just use the 3PDT switch to bypass the LED Resistor combo... yeah? I figure there will be a change in current through the Lamp as a result, but that should only be when the effect is off and therefore not a concern, as long as I set the idle current with the Lamp trimmer while it's all on and fully engaged. Once my power Supply is ready to go I'll give it a try and see if anything unforeseen comes up, in the meantime thanks for the input R.G.! :)