Millenium bypass on 18v?

[sfr]

I've been using the Millenium bypass (Version 1, I believe - with a J201 and a 1N914/4148.) [Edit: this is the file I have printed out over my workbench]

Works well in most of board.  I have a few Yellow LEDs that are a bit dimmer than the other LEDs I use, so if I remember right, I lowered the resistor value slightly to compensate.  (These are in the 9V section of the board, and I don't remember exactly what I did, since it was a while ago. . . )

Anyway, the second half of my board is running off of 18V - most of the pedals inside this have regulators for various voltages.  The millenium bypass on the PT-80 taps voltage off the regulator as per the layout at GGG.  The Trem Lune has a 9V regulator (being the only 9V pedal in that section of the board, it was easier than running another 9V line from my power supply.)  and the millenium taps off of there.  The A/DA flange, and the loop selector box both happen to have the yellow LEDs, and have the millenium bypass hooked up to the 18V supply.  For whatever reason, the LEDs here are *dimmer* than the same LEDs running off of the same millenium circuit when powered off of 9V, regardless of whether I change the resistor value or not.  (I have a feeling I'm not understanding something here, though.) 

I can see several solutions to this problem, like using 3PDTs or whatever, (replacing the yellow LEDs is not one of them - they're JB Welded in and I have better things to do than try and get them out.)  but I'm curious as to what I'm missing.  I'll be rereading the Millenium articles (again!) tonight, but if anyone can explain to me what I need to do to get this circuit to work as expected on 18V, (and why it's different) I'd appreciate it!  (I did check the LEDs before I JB Welded them in and they did reach appropriate brightness - so the LEDs are good - I'll check my wiring once again, but being that the circuit works, just not bright enough, I don't think it's a wiring mishap either.)

[R.G.]

JFETs will pass a maximum amount of current and then stop. They can be and are used as constant current diodes.

If you have 18V to play with, get yourself a high-Idss rated JFET, even if it has Vgsoff = 10V. You have the circuit that can use it.

[sfr]

Thanks!  I didn't even realize that.