Question for all you smart people.

I think an easier way to make that happen (cool idea btw), would be a capacitive switch. I haven't made one yet so I can't really confirm it's viability. I've seen them used mostly in DIY home security circuits- it functions when say, someone puts their hand on a doorknob (maybe the front door, or the door to a room they know they're not supposed to enter! >=^/ ) it will send a signal into the circuit. Sounds like some real cloak and dagger type stuff but I like it. I've seen schematics for this at discovercircuits.com so you can at least check into it. I hope it works out!..

The problem with using a capacitive system is that each string would need to be isolated from the others. Otherwise, you'll touch one string, and set off all four switches. On those style Kramers, the bridge is all metal construction, and on top of that, THE ENTIRE NECK IS ALUMINUM. You would have to isolate each saddle seat from each other, and the plate, then isolate each tuner and string from the neck (pretty sure the nut it's plastic, but if it's aluminum as well, you'll have to isolate there). Good luck pulling that off, though. My question, is why would you do this to such a rare and expensive bass?! Is it a 250, 350, or 450? I understand wanting to teach the kid, but doing this to an Aluminum-Era Kramer? Yikes. Buy a cheap bass down at the pawn shop to put the LEDs in. That way you don't have to worry about modding - and possibly running - factory parts on the Kramer.

what about using photointerrupters around the base of the neck. Cut up some encoder strip

or what about little electromagnetic coils wired as pickups for each string. feed into a quad Opamp to make the detector signal

It's a west German model 250. Aluminum nut. I'm doing it because it was stolen from me when I was 20 years old. The guy had it in a basement that flooded. I have all the original passive electronics and busted all to hell pick guard. I've rebuilt the original pick guard . I have possibly the nicest one that still exists. I've done it in a way that I can convert it back to its original ( very low volume) passive setup in ... Maybe 5 minutes at the most. I've not altered the body or pickup cavity at all , except completely copper shielding the entire cavity and that's not what I would consider altering. I know it's rare . I've played bass for 30 years. That's why I completely restored the original pick guard also. It's 2 basses in one. Wish I could post a picture. Thanks guys you are all very cool and helpfull. I appreciate the info very much.

no way to do it... unless you do some new kind of bridge in one each string have not connection with the other. I think a wood and metal bridge can be usefull but is a lot of work for little function