Another mil bypass question

[Ry]

I know everyone is sick of answering questions about the mil bypass, but I just can't get the thing to work.  I've tried the mil 2 on two different pedals and I just can't get it to work right.  How is the stomp switch supposed to be wired (where is the control line connected)?

Thanks a lot

Ry

[Lonestarjohnny]

Ry, over on the Newb's page there are picture's, and some very good info about doing a Mil. Bypass. also in the archive's there may be some info on it too !
JD

[R.G.]

The Millenium Bypasses are all detectors of a DC path to ground. If you build just the Millenium circuit, no effect, and power it from 9V, then you should be able to turn the LED on by leaving the control line open and turn the LED off by connecting the control line to ground. Until this happens, there is no point in connecting it into the box.

However, once you get the above behaviour, you then have to wire up the switch correctly. Here's a picture: http://geofex.com/FX_images/stompsw.gif

See the lower left hand corner.

[Ry]

Thanks R.G!  I knew I'd seen that picture somewhere!  I have it wired up and working, but it pops when the switch is engaged.  I tried hanging a 1M resistor to ground on both the input and output lines without any reduction of pop.  Is there something else I can try?

Ry

[R.G.]

Thanks R.G! I knew I'd seen that picture somewhere!

Actually, you hadn't ( 8-) ). I just reworked a wiring picture that I had up at GEO before to include Millenium wiring instead of ground-the-input wiring, but it does look very similar. I think the millenium wiring is more pertinent today than the other permutation.

I have it wired up and working, but it pops when the switch is engaged. I tried hanging a 1M resistor to ground on both the input and output lines without any reduction of pop. Is there something else I can try?

The Millenium doesn't (shouldn't, at least, when wired right) have any effect on popping, positive or negative. The Millenium Bypass doesn't cure popping that already exists, just doesn't make it any worse.

I suspect your effect pops without the Millenium attached if the Millenium is working right and the wiring is correct. The fact that the pulldown resistors have no effect is suggestive of some path for DC to the effect input and/or output. That is usually a shorted or reverse polarity input or output capacitor not blocking DC from the effects internal workings getting out on the signal lines.

Measure the DC voltage on your effect's input and output. It should be 0.000V with the effect powered up. If it's not, the effect will pop when switched.

[Ry]

The strange thing is that it does not pop at all when the mil bypass is not connected.  It pops when the effect is turned on with the mil bypass connected.  

It works great, turning the LED on and off, but the pop is terrible.

Thanks for updating the drawing!

Ry

[mirza]

i found all of board wiring on tonepad...
it's all explaned very well
also, i found somewhere info on stomp switches...they must be worked out if there is a pop.....unplug power and push stomp 20 times and pop should disapear...this worked for me....:-/

[R.G.]

The strange thing is that it does not pop at all when the mil bypass is not connected. It pops when the effect is turned on with the mil bypass connected.

Two things come to mind - did you get the leakage diode in the right direction? Cathode (bar) to +9, anode (arrow) to the gate? That would do a terrible pop. Second, does the LED share power or ground line with the effect circuit?

The Millenium Bypass, when properly set up and wired does not cause a pop, by design and by actual experience of many people.

A couple of things to try:
(1) disconnect the control wire from the stomp switch temporarily, and tack-solder it to one end of a 1M resistor. Turn the effect on, and then touch a grounded place (barrel of a jack, grounded enclosure, etc.) with the free end of the 1M. (a) does the LED go on and off? and (b) do you hear a pop? Try this with effect bypassed and engaged. This change does not affect the effect operation or bypassing at all, just the LED operation.
(2)Put the control line back on the stomp switch where it was. Measure the DC voltage on your effect output in both bypass and non bypassed modes. Let it sit for several seconds to ensure any cap charging has taken place.

Let me know what happens.

[Ry]

Sorry it took a while to get back with you, I was recovering form a weekend canyoneering trip  

Okay, here's what I did:

I had the switch wired differently that your diagram, so I fixed that.  The pop is still present and now the led turns on faintly while the effect is off, and the led is off when the effect is on.

did you get the leakage diode in the right direction? Cathode (bar) to +9, anode (arrow) to the gate

Yes, I measured this and checked the voltage.  It is correct.  By the way, I used a 2N7000 for the FET.

Second, does the LED share power or ground line with the effect circuit?

Power

(1) disconnect the control wire from the stomp switch temporarily, and tack-solder it to one end of a 1M resistor. Turn the effect on, and then touch a grounded place (barrel of a jack, grounded enclosure, etc.) with the free end of the 1M. (a) does the LED go on and off?

No, it does turn on when I scrape the control line against the case, but not throught the 1M resistor.

(2)Put the control line back on the stomp switch where it was. Measure the DC voltage on your effect output in both bypass and non bypassed modes. Let it sit for several seconds to ensure any cap charging has taken place

There is between .1 and .9 mV, the upper values are almost certainly from a cap discharging, it's usually around .1 mV.

Thanks!

Ry

[brett]

Hi.
Make sure that your 2N7000 is oriented the OPPOSITE of the BS170 that RG shows in his diagrams.
Can't think why I thought that might be relevant.  Brain is dead....(Anybody else working on a thesis?  3 weeks to go, 100 pages need severe work)
cheers

[R.G.]

The pop is still present and now the led turns on faintly while the effect is off, and the led is off when the effect is on. ...
No, it does turn on when I scrape the control line against the case, but not throught the 1M resistor.

Then your Mill 2 circuit is not wired/working correctly. A properly setup Mill 2 will work through a 1M resistor on the control line to ground. That is, a control line with 1M to ground is pulled to ground within 10mv, which is enough to turn the MOSFET off by pulling the gate-source voltage below 0.5v; and with an open circuit, the diode leakage is enough to pull the MOSFET gate above 3.0V, a guaranteed fully-turned-on condition, so the MOSFET pulls the LED to ground.

Get the Mill 2 circuit working with a 100K-1M resistor first.

As Brett says, make sure that the 2N7000 pinout you're using is correct. I dimly remember some 2N7000's having different pinouts from one another, so you may have to look up the one for your manufacturer's device. I can see what you say happening if the 2N7000 had source where the drain is expected and drain where the gate pin is expected. That might turn the LED on when the control line is hard-shorted to case.

This kind of problem is one reason I genned up the Millenium C - which just uses a CMOS inverter instead of a discrete MOSFET. The CMOS hex inverter is much more widely available, and has a guaranteed pinout.