LED in pickup curcuit?

I'm looking at a pickup & electronics upgrade for an IB-5 which would use three pots, leaving an extra hole in the body. I could mount a dummy knob but was wondering about an LED instead. Would it hurt the output? Would it glow brighter based on the volume or pitch being played?

Hmm, I wonder if anyone makes a tiny VU meter...

Seeing as a typical passive pickup outputs about 0.1v peak, and an LED needs at least 1.8v-3.3v across it before it starts conducting. An active pickup or preamp might put out a bit more, but not that much. So without a dedicated active circuit to drive it, it won’t work.

There are small VU meters, but modern meters run on DC, do you’ll need to rectify the signal and then amplify it as 0VU is 1.288v, otherwise you won’t get much more than a flicker at the bottom end of the scale. Again, to make it work, you need some active electronics to make it work.

What circuitry for just three pots on an IB5? Adding a pickup selector switch?

You could add a single-coil switch if the pups are humbuckers...

Let’s find out what the pickups and circuit is first. There may be some other options that can make better use of the hole.

There will be power. I'm looking at active pickups from EMG. I'd expand the control cavity to make room for a battery or two.

EMG's wiring diagrams for two pickups have three controls, volume/volume/tone (they also offer an active balance control but I won't be buying it). They do mention an option for a three-position switch, but it seems almost redundant with two volume controls.

https://www.emgpickups.com/pub/media...230-0128rb.pdf
https://www.emgpickups.com/pub/media...230-0208rb.pdf

It will be interesting to see what Simon suggests. The lovely thing about EMGs is that they are plug and play, and also very quiet. I have a set in a bass, and it's pretty much the only bass/guitar I use where I am not inclined to mess with the electronics.

You could add an LED, but I am not sure what it would tell you other than that you have a cable plugged in. Might not be the worst thing in the world. Most active basses turn the active electronics on and off when you plug and unplug the cable. I killed a number of batteries in my one active bass by forgetting to unplug it. The light would be a reminder to unplug when you've finished playing ;-)

An always-on LED to show the jack was plugged in would draw far more power (typically 20mA) than the EMG circuit does (they say 0.08mA), so would probably give a battery life of around 30 hours at best with 9v alkaline batteries, instead of the 1000 hours EMG suggest for the pickups alone. And having two batteries for 18v doesn’t improve things as they are in series, not parallel, so the current draw is the same through both batteries.

I don’t know if you are happy with the basic sound of the EMG bass pickups, but my guitar ones ( DG20 pickguard installation on a Strat) sound a bit ‘meh’ and dull without the EXG control turned up to about halfway to give the pickups their ‘Stratiness’ back.

So I’d strongly suggest just putting a rubber bung in the spare hole for now, as I think you will benefit from some of the tone-shaping options EMG have to offer.

Not a recommendation, but out of curiosity, couldn't each pickup be wired for 1 V 1T. It looks to my uneducated eye like you you could something like diagram 3 twice. The first time exactly as in Diagram 3, the second time with the red lead from the pup going to the middle terminal of the battery bus. It would mean splicing in the two leads from the tone control that go to S and T on the jack, but that's a pretty mod...if it would work. Would this be a way to get two independent pickups with 1T and 1V each? Would that solve the hole problem? (pun is, of course, intended).

Thanks you two for the input and feedback. A better knowledge of electronics is a skill I should pickup. (Am I doing this right, Fender?)

The EMG EXB is the bass expander version of the EXG. Might be worth thinking about as a future addition. You could do something similar with active bass, middle and treble controls by cutting the mids a bit and boosting the bass and treble, but this does it all at once and with one knob. It’s like having two sets of pickups to chose from to my ears (with the EXG modified version sounding much better). I find that midway is a better setting than full on, which can be a bit too scooped.