Millenium bypass issues

[JebemMajke]

So I've tried that one from analog alchemy, that one from AMZ website, first two from geofex ( NPN and Nfet ) and the one from general guitar website. Only the Nfet bypass versions did work, but they had some leakage ( in off position they would lit up in 5-10 seconds ). Maybe because I've used Bf 245 and 2sk30, but those are the fet's i had. What am I doing wrong? Any ideas?

I haven't tried millenium 2 ( the one with with mosfet ), it's on the menu today.

[bluebunny]

Go with the M2.  I build loads and they're very reliable (thanks R.G.!).  Just make sure your FX output has a route to ground (otherwise the LED will fade back in).  BTW, I like to build mine on scraps of vero: I have 6x6 and 4x9 layouts for the offcuts I seem to generate...

[JebemMajke]

I'm just about to solder the diodes and I'm not sure if they connect with input or go "above" it?

[R.G.]

I'm just about to solder the diodes and I'm not sure if they connect with input or go "above" it?

Input, gate, and both diodes connect together there.

[bluebunny]

That's a four-way connection.  BTW, the "low leakage diode" is the C-B junction of an NPN transistor (the example from GEOFEX is 2N3904).  Be sure to check out "The Millenium C(ontinues)" at GEOFEX.

(Looks like R.G. got in there first while I was typing!)

[bluebunny]

FYI, here's what I do with my vero offcuts:



Q1 is BS170.  If you substitute a 2N7000, face it the other way.  Q2 is 2N3904.  As R.G. suggests, season to taste with whatever resistor values suit.

[JebemMajke]

Ok, here goes, it works! But I have some issues. I've placed 50k trimpot in place of resistor and bc550c as low leakage diode. Bs170 and green led. If resistance is zero led is at it's fullest but there is almost no sound. If I introduce some resistance the sound is back but the light is somewhat dimmed. I would like to be at it's shiniest and to have full volume. The circuit I've tested this with was and is Fetzer valve plus 100k resistor at the output.

Can you post schematics of those please, i don't know how to read vero 

[JebemMajke]

Mosfet millenium from this pdf here ( http://www.geofex.com/Article_Folders/Millenium/The%20Next%20Millenium.pdf ) works great

Thanks R.G. for coming up with this

And thank you bluebunny for your help.

Ps i made it really small 1x2,3 cm. I guess I could make it smaller, but trimpot takes a lot of space.

[bluebunny]

Ok, here goes, it works! But I have some issues. I've placed 50k trimpot in place of resistor and bc550c as low leakage diode. Bs170 and green led. If resistance is zero led is at it's fullest but there is almost no sound. If I introduce some resistance the sound is back but the light is somewhat dimmed. I would like to be at it's shiniest and to have full volume. The circuit I've tested this with was and is Fetzer valve plus 100k resistor at the output.

Can you post schematics of those please, i don't know how to read vero 

I'm a little confused by what you've said here, and I'm not sure if you're using the M2 in the right way.  First of all, if you're talking about using a trimmer in place of the LED resistor (R1 in the schematic below), then zero is a bad thing - you'll be supplying a full 9V to the LED, which will burn it out.    Anything over 390R will work fine (for a bog-standard red LED) - my choices of around 1K5 give a balance between brightness and current consumption.  BTW, the other resistor (10K in my layouts; R2 in the schematic below) is pretty much a random value according to R.G. and may even be omitted.

Anyway, to the second point.  If you're finding a relationship between LED brightness and the volume of your circuit, then it's most likely wired up wrong!    When your FX circuit is "on", it's not connected to the M2.  So one cannot affect the other.  When your FX circuit is "off", its output is connected to the control input of the M2, providing a DC route to ground, and this switches the LED off.  I routinely use the wiring diagram in the "offboard wiring" article at Tonepad (click on the tonepad_offboardwiring.pdf link).  Check out page 3 for wiring up a Millenium board.

BTW, this is the M2 schematic I'm working from:



This is from the "Next Millenium" PDF on R.G.'s site which you've already found.

[JebemMajke]

There weren't any issues relating led-killing-volume, the circuit I've used for testing wasn't biased properly. Hence the "volume issues". For that test I've used this schematic , and the led survived with zero ohms xD.

And on the last post I've used that schematic you've posted in the previous post, and that exact wiring and it works since than.

[bluebunny]

... and it works ...

This is the most important detail! 

[JebemMajke]

Having issue with Millenium 2 and fuzz face, LED won't turn off.
Here's schematic

Any idea?

[JebemMajke]

Ps, for low leakage diode I've used bf224. I have a lot of them and they are useless in any other project. Could that be the problem?

Edit

In order to replace bf224 with the usual bc548 I took it out and all of a sudden voila, it works??? I've placed bc548 and bc549 and other NPN transistors and it only works when there is nothing in place of low leakage diode.

[merlinb]

Ps, for low leakage diode I've used bf224. I have a lot of them and they are useless in any other project. Could that be the problem?

Edit

In order to replace bf224 with the usual bc548 I took it out and all of a sudden voila, it works??? I've placed bc548 and bc549 and other NPN transistors and it only works when there is nothing in place of low leakage diode.

You don't actually need the low-leakage diode- it doesn't do anything useful. I think RG put it there to supposedly protect against gain-source overvoltage, but that simply can't happen in a 9V circuit. The low leakage diode is redundant.

[R.G.]

You don't actually need the low-leakage diode- it doesn't do anything useful. I think RG put it there to supposedly protect against gain-source overvoltage, but that simply can't happen in a 9V circuit. The low leakage diode is redundant.

I would say that another way. The low leakage device is not active in normal circuit operations. It is a protective device against electrostatic transients. It is only active during installation if you put the Millenium Bypass in as a retrofit, or if your circuit has some hefty electrostatic discharges during operation. It is redundant and does nothing useful in the same way that a fire extinguisher does.

[merlinb]

It is only active during installation if you put the Millenium Bypass in as a retrofit, or if your circuit has some hefty electrostatic discharges during operation.

As long as the circuit runs off less than about 20V, you can't get gate-source overvoltage anyway, since the gate will be clamped to the supply voltage by the other diode. So it's redundant in the same way as a fire extinguisher in a room that can't catch fire!

[Kesh]

electrostatic at the gate doesn't really care what the supply rails are doing, if it's below the potential of the 9V rail then hundreds or thousands of volts will go through the mosfet if it's without protection diodes. normally this is a zener series pair to ground rated above the gate voltages expected, but that doesn't really apply in the M2.

rooms that don't catch fire are like people that don't walk across carpets prior to picking up their pedals. not that common.

[JebemMajke]

Can I use multiple LEDs? Like 3 or 4?

[R.G.]

It is only active during installation if you put the Millenium Bypass in as a retrofit, or if your circuit has some hefty electrostatic discharges during operation.

As long as the circuit runs off less than about 20V, you can't get gate-source overvoltage anyway, since the gate will be clamped to the supply voltage by the other diode. So it's redundant in the same way as a fire extinguisher in a room that can't catch fire!

You are absolutely correct, in theory. As Yogi Berra said, "in theory, theory is the same as practice; in practice, it isn't". In a properly constructed circuit, once the parts are all soldered in, there isn't any predictable way that the voltage on the gate could get outside the power supplies. In a properly constructed fireproof room, you don't need a fire extinguisher - until someone walks in with a can of gasoline, or even a can of paint. Probably - probably - you don't even need the extinguisher then.

However, Mother Nature has taught me that the world can be a complex place, which is simply another way of saying that theories are abstracts, simplified models of how things work when there are no other confounding or hidden factors.

The original version of that circuit did not have the low leakage diode in it, and the circuit works fine without it. It's the single most confusing part in the circuit, and the subject of probably 75% of the questions I get on the circuit. So I go through the explanation that it's not needed for operations, but is a protection device only, another time for every few beginners that try it.  As a side light, about 20% of the questions go "my Millenium 2 LED is always on - what's wrong? I did every thing exactly correct." In that case, it is almost always getting the MOSFET turned around backwards.

By the way, I'm sure you're familiar with the fact that 86% of all statistics are made up on the spot, right?   

So here's the pronouncement I generally make - Hey! To everyone making a Millenium 2: the low leakage diode is a protection device. It's mostly never needed. I advise you to put it in there, or I would not have put it into the schematic. But you're free to leave it out, and probably - probably - your Millenium 2 will work fine without it.

If you leave it out, it would make sense to take electrostatic precautions when you're constructing the circuit and installing it in the pedal, and also whenever you change the battery in the circuit, as when the battery is removed there is not a good clamping element in the circuit to clamp the static sparks under +/-20V on the gate. Likewise, be careful about plugging in daisy chains, as this exposes the power and ground lines to electrostatic arcs and also disconnects the battery, so that electrostatic sparks can get at your circuits, including any Millenium 2s. This is very unlikely, of course, so if you just want to take responsibility for debugging and replacing parts in the unlikely event it ever does happen, you can choose to leave the low leakage diode out.

Can I use multiple LEDs? Like 3 or 4?

For the LED it lights? Depends on how you hook them up. LEDs take 1.5 to 3V mostly, so if you want to run from 9V and have 3V LEDs and want to stack them in series, the best you can do is two - there has to be some voltage left over from the power supply for the series current limiting resistor. If you hook up a bunch of LED+resistor sets in parallel, you can drive lots of LEDs. The common MOSFETs for this are the BS170 and 2N7000, which are good up to ... 600ma, I think. I didn't look it up. At 10ma per LED+resistor, that's a whole bunch of LEDs you can light.

Did you mean can you use LEDs for the low leakage diode??

[JebemMajke]

Did you mean can you use LEDs for the low leakage diode??

Nope

If you hook up a bunch of LED+resistor sets in parallel, you can drive lots of LEDs.

This is what I wanted to know. So can you explain how? What would the values of resistors be?