Mooer Leveline volume pedal dissected. How on earth does this work???

[exabrial]

I dissected my Mooer Leveline volume pedal. My intention was to see if I could replace the pot in it with a log taper for more action near the bottom of the pedal.


Except there is no pot. How on earth does this thing work?

[digi2t]

Is there a magnet, or magnetic piece on the treadle? If so, it might be with a proximity sensor, like the Sonuus Wahoo.

[exabrial]

Tried messing with the potentiometers in there. The right one affects how sensitive the pedal is to it's sensors. If you twist one way, it stays on 100% of the time. If you twist all the way it will never turn on.

The one of the left changes the rate of which the volume changes. Turn all the way one way, and you get a very very linear increase but the guitar will never full mute. Turning it all the way the other way keeps the pedal dead quiet to all but the very end of it's range and your guitar pops in very suddenly.

[exabrial]

Is there a magnet, or magnetic piece on the treadle? If so, it might be with a proximity sensor, like the Sonuus Wahoo.

I tried holding a steel screwdriver to the bottom of the rocker arm and it didn't stick... tried holding a magnet close by with no effect either. Crazy!

[aron]

It looks really great. Yes, I wonder how it works.....

[lapsteelman]

Force Sensing Resistor?

[nosamiam]

Is that gray square in the last picture an LDR? It looks like the treadle has a "tongue" (for lack of a better word) that hangs down. The bottom of it has a 90 degree bend in it that possibly lines up with that gray square. Does it raise and lower over the square and cut off the light reaching it? If so, is there a steady light source somewhere inside the enclosure? If that's how it works, it should be pretty reliable and quiet.

You could test it out by plugging into the base with the treadle still removed. Send a signal through it and cover and uncover that square with a finger. Volume should go up and down.

**edit: I can see the LED peeking out under that rubber pad in the last picture. That LED shines on the LDR. The metal arm descends and blocks the light reaching the LDR. That would be my guess.

[exabrial]

Is that gray square in the last picture an LDR? It looks like the treadle has a "tongue" (for lack of a better word) that hangs down. The bottom of it has a 90 degree bend in it that possibly lines up with that gray square. Does it raise and lower over the square and cut off the light reaching it? If so, is there a steady light source somewhere inside the enclosure? If that's how it works, it should be pretty reliable and quiet.

You could test it out by plugging into the base with the treadle still removed. Send a signal through it and cover and uncover that square with a finger. Volume should go up and down.

**edit: I can see the LED peeking out under that rubber pad in the last picture. That LED shines on the LDR. The metal arm descends and blocks the light reaching the LDR. That would be my guess.

Ah... I flipped the main board over. The "paddle" descends towards this component in the top left of the first pic ("u5" on the circuitboard)



Paddle in full volume position (look under r46 c35):




Paddle in mute position (look under r46 c35):

[nosamiam]

Makes sense. But the gray square under the rubber pad? Is that a pressure sensor? It looks more like that than an LDR anyway. Maybe it uses the LDR for most of the sweep, but the pressure sensors make sure that regardless of how the trim pots are adjusted, you still get full-on and full-mute at the extremes of the pedal's movement.

[exabrial]

Makes sense. But the gray square under the rubber pad? Is that a pressure sensor? It looks more like that than an LDR anyway. Maybe it uses the LDR for most of the sweep, but the pressure sensors make sure that regardless of how the trim pots are adjusted, you still get full-on and full-mute at the extremes of the pedal's movement.

Yah I'm fairly certain they are pressure sensors, not LDRs. There is a rubber bad on the end of the lever arm that touches it in the forward and rear. Probably sets the internal amplifier to full blast/mute.


What is that strange u5 component? Has to be some sort of metal detector or inductor or something.

[nosamiam]

U5 definitely isn't an LDR? Does it line up with the paddle when the pedal is assembled? It's hard to get a sense of how it all fits together.

[exabrial]

Sorry, I meant I doubt the pieces under the rubber are LDRs, most likely pressure sensors.

Yes, U5 lines up with the paddle. I don't think u5 is an LDR though.

[nosamiam]

Interesting. Not sure what it could be. Have to wait to see what the gurus say.

[deadastronaut]

wierd...

hall effect......IR....hmmm....curious now...

[duck_arse]

who did the power mosfet (??) mod, and can we see a good pic of the treadle underside?

[PRR]

Looks to me like a lamp, foot-operated flag, and light sensor.

The way the "LEDs" are mounted, they *may* be bouncing light off the insides of the enclosure. Pictures are too big to see.

The light sensor may not be a photo-resistor directly slamming the audio. Photo-Rs are going out of style (or production) because of no-Lead-laws. Simple enough (for a factory) to take any variable voltage and work a voltage controlled amplifier.

[thermionix]

because of no-Lead-laws

I've heard it's the cadmium in LDRs, but I am NO expert on this stuff!  Have you seen the EU/RoHS-compliant Fender blackface reissues, what they use instead of the optoisolator in the trem circuit?  Ridiculous!

[potul]

Definitively U5 seems to be the sensing element.

Maybe a hall effect sensor?

[exabrial]

Sorry, I had to put the pedal back together so I could use it LOL.

There's no mods done to it, that's they way it came.

The LEDs don't have anything to do with it I think, they're facing out, AND they're shrouded black internally (strange).

Hall effect sensors seem to have 3 leads :/ That's what I want it to be haha.

The paddle is steel, whereas the rest of the body is alum.

See the first image for a closeup of the bottom of the rocker arm. There's not sensors or wiring there.

I have a feeling it's likely an LED/photoresistor combo (4 leads), but I can't find a part that even remotely looks like it!

[exabrial]

HEEEEEY. check this out!

http://www.digikey.com/product-detail/en/fairchild-semiconductor/QRE1113GR/QRE1113GRCT-ND/965713


What do you guys think??