MXR Distortion + / problem with millenium 1

[Hexa]

Hello,

First, thank you very much for the good job your doing here ... it's really helpfull :-)

I just build a MXR distortion + and tryed to include the millenium bypass. Everything works fine exepting the led of the millenium which is still brite when effect is bypassed. What is more strange is that the millenium LED works as it should do when FX level is at the maximum or at the minimum ... and when level is on all intermediate position LED is brighting even when bypassed 

Someone have any idea ??

Many many thanks in advance

[Gargantua]

The Millenium effect works by sensing the impedance referenced to ground.  What version Millenium are you implementing?  I've used a npn 3904 transistor with a 26.5K ohm resistor or potentiometer between the collector to base and had the LED forward biased with the anode facing the emitter junction.  The LED cathode is then connected to battery ground(not the 4.5vdc virtual ground).  When you use a 30k trimmer between the collector and base junction, you can calibrate the trigger point which is approx 26.5k ohms.  That of course is if you are using a 10k potentiometer to adjust the over all output of the effect.

Gargantua

[Hexa]

THank you very much for the reply :-))

To be more accurate on what I've done I used the tonepad MXR disto schematics + GEOFEX millenium 1 plus N channel schem.

http://www.tonepad.com/getFile.asp?id=4

http://aronnelson.com/gallery/TheBigMan-Layouts/mb

The ground of the millenium is connected to where all ground are connected (input jack ground) , I've used a 2N5485 transistor onto it, resistors are 4.7K and 1K as on the schematics and the diode is a 1N914

[Hexa]

Hi also tried to put a 100K resitor between effect output and the ground ... it unfortunaly doesn't change anything 

You said you connect the millenium ground directly to the battery ground ... On my side I've connected the battery and the millenium ground directly to the fx main ground (input jack), so I'm not sure this could change anything   

[Gargantua]

I took the concept of the Millenium 1 and changed it.  I took a 3904 npn resistor because thats all i had at the time and connected a 27k ohm resistor between the base and collector.  the LED anode junction was facing the emmitter with a l.0 k ohm resistor in series to prevent burning.  The cathode of the LED was then connected to battery ground.  I have not looked at the schematic of the MXR but im sure they have created a vitual ground point that uses 4.5vdc from the 9vdc voltage divider circuit.  My circuit will only work if the output impedance is around 10k or less so if you duplicate this, you may have to lower the impedance to 10k which is really what you want anyway to drive loads.  The distorion circuit i designed uses a 10k ohm pot on the output of the opamp so a 10k ohm resistor is not needed.  Its a 2 channel device with two individual gain stages and two different filter controls.  I originally designed it for bass but it works well with guitar granted that is has a humbucker distortion pedal.  I am going to implement a switch so it can be toggled between bass and guitar.  This switch will change the filter cap in doing so, will change its frequency response.  goodluck. I shall post a schematic soon.

gargantua

[Hexa]

Gargantua ... I've sent a quick drawing to you via MP ... just let me know if I good undestood the concept (Which is really not 100% ... sure)  :-)) THen I will put it on the forum :-)