Millenium bypass

meffcio · Post by **meffcio** » 28 Feb 2010, 16:25

sinner wrote:Small input from me.

This is Millenium bypass based on AbuseArt's layout with onboard DPDT switch. Next move is to make it with 4PDT to be used with stereo FX's

It's not verified, my first PCB drawing, so be gentle I hope it fits

Any vectorized version? I mean a pdf file with the circuit being um... objects? curves? But not an image.

Bside2234 · Post by **Bside2234** » 03 Mar 2010, 03:17

mictester wrote:
Bside2234 wrote:It's the one in the 4th post from the top with the 1k on the control. I actually thought about the pull-down resistor after I posted. I'll have to try it out.
OK. Let us all know if that was the problem - it's always good to know when something gets fixed!

A 1M from input to ground didn't work. Still pops like mad. I also noticed the LED is coming on when the effect is off instead of on. Something is backwards.

mictester · Post by **mictester** » 03 Mar 2010, 13:40

Bside2234 wrote:
mictester wrote:
Bside2234 wrote:It's the one in the 4th post from the top with the 1k on the control. I actually thought about the pull-down resistor after I posted. I'll have to try it out.
OK. Let us all know if that was the problem - it's always good to know when something gets fixed!
A 1M from input to ground didn't work. Still pops like mad. I also noticed the LED is coming on when the effect is off instead of on. Something is backwards.

Aha! You've probably got the control line coming from the wrong contact on the switch!

Bside2234 · Post by **Bside2234** » 03 Mar 2010, 16:34

I don't think so.
Here is what I have. I am going to double check my wiring just to make sure.

: v3.jpg (13.6 KiB) Viewed 2416 times

IvIark · Post by **IvIark** » 03 Mar 2010, 16:54

I did this version to go on a solder strip that I could fit in a narrow space:

meffcio · Post by **meffcio** » 05 Apr 2010, 17:27

sinner wrote:Small input from me.

This is Millenium bypass based on AbuseArt's layout with onboard DPDT switch. Next move is to make it with 4PDT to be used with stereo FX's

It's not verified, my first PCB drawing, so be gentle I hope it fits

Could you send me the project files to placebo91@gmail.com?

higgy · Post by **higgy** » 29 Apr 2010, 16:54

Hi,

I am new to this Millenium bypass malarky, but I find myself needing one in a stereo bypass switch I am building. I confess I am a bit confused by all the different variants "Mellennium", "Millennium 2", Millenium 2 plus", "Millenium C"....

I'd really appreciate some advice from someone who has successfully constructed one of these. Which circuit did you choose, and why.

Thanks!
- Nick.

mictester · Post by **mictester** » 29 Apr 2010, 17:13

higgy wrote:Hi,

I am new to this Millenium bypass malarky, but I find myself needing one in a stereo bypass switch I am building. I confess I am a bit confused by all the different variants "Mellennium", "Millennium 2", Millenium 2 plus", "Millenium C"....

I'd really appreciate some advice from someone who has successfully constructed one of these. Which circuit did you choose, and why.

Thanks!
- Nick.

Show us a schematic of what you're trying to switch, and what switches you're using. The Millennium circuit is easy to get going, but you need to understand it!

higgy · Post by **higgy** » 29 Apr 2010, 18:08

mictester wrote:
Show us a schematic of what you're trying to switch, and what switches you're using. The Millennium circuit is easy to get going, but you need to understand it!

Ha ha ha! That's not too easy. It's required in my rather complicated switch box! I play guitar, bass and a twin-neck (with a stereo output to allow selection by foot). I'll draw it up this evening and post it. I suspect I am going to need to explain!!!

Jarno · Post by **Jarno** » 29 Apr 2010, 20:31

I did a PCB layout with onboard pads for a Alpha DPDT, but I'm still trying to get the millennium 2, which is also on the PCB, to work. It's a finicky bugger! I got a faint glow in "off" and adding a parallel 4.7k across the LED didn't help. changed the led to a green one (as opposed to the blue one earlier) and now it's always on, sounds like a new mosfet is called for.

mictester · Post by **mictester** » 29 Apr 2010, 23:49

higgy wrote:
mictester wrote:
Show us a schematic of what you're trying to switch, and what switches you're using. The Millennium circuit is easy to get going, but you need to understand it!
Ha ha ha! That's not too easy. It's required in my rather complicated switch box! I play guitar, bass and a twin-neck (with a stereo output to allow selection by foot). I'll draw it up this evening and post it. I suspect I am going to need to explain!!!

Perhaps you will, but I'll try to help!

higgy · Post by **higgy** » 30 Apr 2010, 15:24

In drawing up my circuit I have found that there is a fault. Although in most configurations the millenium bypass will connect to the output of the last pedal in the effect loop. in one condition it will not, therefore it's not going to work!!!

mictester · Post by **mictester** » 30 Apr 2010, 17:45

Jarno wrote:I did a PCB layout with onboard pads for a Alpha DPDT, but I'm still trying to get the millennium 2, which is also on the PCB, to work. It's a finicky bugger! I got a faint glow in "off" and adding a parallel 4.7k across the LED didn't help. changed the led to a green one (as opposed to the blue one earlier) and now it's always on, sounds like a new mosfet is called for.

What circuit did you use? This always works for me:

: millenium.png (1.08 KiB) Viewed 2279 times

The MOSFET is a BS170, the transistor is a 2N3904 (I've got thousands of them), and the diode is a 1N4148.

You need to understand the principles of the circuit!

Barcode · Post by **Barcode** » 01 May 2010, 00:39

higgy wrote:In drawing up my circuit I have found that there is a fault. Although in most configurations the millenium bypass will connect to the output of the last pedal in the effect loop. in one condition it will not, therefore it's not going to work!!!

I'm confused by this. There is no "last pedal" requirement in the circuit. It works individually on whatever effect you put it on, the pedals around it are not involved...

Jarno · Post by **Jarno** » 01 May 2010, 07:59

mictester wrote:
Jarno wrote:I did a PCB layout with onboard pads for a Alpha DPDT, but I'm still trying to get the millennium 2, which is also on the PCB, to work. It's a finicky bugger! I got a faint glow in "off" and adding a parallel 4.7k across the LED didn't help. changed the led to a green one (as opposed to the blue one earlier) and now it's always on, sounds like a new mosfet is called for.

What circuit did you use? This always works for me:

millenium.png
The MOSFET is a BS170, the transistor is a 2N3904 (I've got thousands of them), and the diode is a 1N4148.

You need to understand the principles of the circuit!

I used BS170 and 2N3904 as well, as well as the 1N4148, and the exact same schematic. Could be the fact that I used a blue LED, but even if you're using a more conventional LED, there's quite some variation in forward voltage drop, it could very well be the problem.
In all fairness, I just need to do some more tweaking, I haven't looked at it THAT long. It's just that I'm used to things working on first startup

mictester · Post by **mictester** » 01 May 2010, 08:28

Jarno wrote:
mictester wrote:
Jarno wrote:I did a PCB layout with onboard pads for a Alpha DPDT, but I'm still trying to get the millennium 2, which is also on the PCB, to work. It's a finicky bugger! I got a faint glow in "off" and adding a parallel 4.7k across the LED didn't help. changed the led to a green one (as opposed to the blue one earlier) and now it's always on, sounds like a new mosfet is called for.

What circuit did you use? This always works for me:

The attachment millenium.png is no longer available
The MOSFET is a BS170, the transistor is a 2N3904 (I've got thousands of them), and the diode is a 1N4148.

You need to understand the principles of the circuit!
I used BS170 and 2N3904 as well, as well as the 1N4148, and the exact same schematic. Could be the fact that I used a blue LED, but even if you're using a more conventional LED, there's quite some variation in forward voltage drop, it could very well be the problem.
In all fairness, I just need to do some more tweaking, I haven't looked at it THAT long. It's just that I'm used to things working on first startup

Let's look at the circuit:

: millenium.png (1.34 KiB) Viewed 2257 times

The resistor in the final stage of the effect is crucial. If you don't have a pot in that position (like in a Big Muff Pi), you'll have a capacitor from the final stage. You might need to add a pulldown resistor - perhaps 100k - after that output capacitor if there isn't one fitted. This won't have the slightest effect on the sound of the circuit, but will guarantee that the indicator circuit switches properly.

In the "Bypassed" state, the pulldown gets connected to the gate of the FET, and because of the very high resistances on the gate, it is pulled (effectively) to ground potential. This turns the LED firmly off. If you don't have a final stage pulldown (either a pot as drawn or a resistor after the output capacitor) the LED will probably remain on!

Don't be confused by the 1N4148 and the transistor - they are just very high value resistors! You could easily replace them with (say) a 47M resistor from gate to +9V and 100M from gate to ground to get the same results, but these aren't common values, and any slight leakage (from greasy fingerprints or even water vapour) could mess with the operation of the circuit, so it's best to keep everything tightly together.

When you realise that the end of your effect circuit is part of the indicator circuit (you're just switching in a resistor from gate to ground to turn the LED off), you'll quickly discover what's wrong!

Jarno · Post by **Jarno** » 01 May 2010, 12:18

Haven't got it hooked up to an effect yet, I've used a variety of resistors to do thw switching, 220k 100k down to 4k7.
I'll have a better look at it and yet y'all know. Thanks for the help!

higgy · Post by **higgy** » 20 Jul 2010, 08:54

Barcode wrote:
higgy wrote:In drawing up my circuit I have found that there is a fault. Although in most configurations the millenium bypass will connect to the output of the last pedal in the effect loop. in one condition it will not, therefore it's not going to work!!!
I'm confused by this. There is no "last pedal" requirement in the circuit. It works individually on whatever effect you put it on, the pedals around it are not involved...

Well the control signal must have two states, right?

With the switch in one position it connects to 9v (or is it ground, I forget), but in the other it is connected to the output of the last pedal in the loop.... no?

mictester · Post by **mictester** » 20 Jul 2010, 12:06

higgy wrote:
With the switch in one position it connects to 9v (or is it ground, I forget), but in the other it is connected to the output of the last pedal in the loop.... no?

No. In the bypassed condition the input of the circuit is connected through the output resistor (or pot) of the effect to ground. This turns off the LED. In the "effect on" position, the input of the circuit is left disconnected, and the very high value resistors on the gate of the FET turn the LED on. Simple!

ryanuk · Post by **ryanuk** » 11 Jan 2011, 20:16

mictester wrote:
higgy wrote:
With the switch in one position it connects to 9v (or is it ground, I forget), but in the other it is connected to the output of the last pedal in the loop.... no?
No. In the bypassed condition the input of the circuit is connected through the output resistor (or pot) of the effect to ground. This turns off the LED. In the "effect on" position, the input of the circuit is left disconnected, and the very high value resistors on the gate of the FET turn the LED on. Simple!

I'm really having trouble understanding this circuit; I've built a few and they work fine, but I really would like to understand the principle.

RG Keen's article suggests (and its likely I'm completely wrong) that, when the effect is "on", the reversed diode provides a small current for the JFET, which therefore turns it on and allows the LED to light. Conversely, when the circuit is "off", the gate junction is effectively gounded and therefore the FET and LED are off.

However, Wikipedia's JFET definition of JFET includes this description... "By applying a bias voltage to a "gate" terminal, the channel is "pinched", so that the electric current is impeded or switched off completely." This kinda contradicts my understanding. i.e. a current across the diode would switch the FET (and LED) off??

Another Internet source states that a JFET channel conducts with no voltage at the gate!!!

I know this is basic stuff and I should be able o grasp it but I'm having real trouble!!! Can someone help!!??

RyUK