Need help w/ organ vol. pedal -> rotary speak. speed pedal (pics)

[daviddec]

I have a volume pedal from an organ and a rotary speaker from the same organ, and I was hoping to use the rocker volume pedal as an "expression pedal" to control the speed of the rotary speak.  The rotary speaker has a switch to make it start spinning and another switch to adjust either slow or fast speed.  It'd be great if anyone out there could guide me in wiring this.  Here are some images of the pedal, as you can see it's quite old but still works.  I think the two pots are stereo channels as the speakers on it were wired in stereo.




Any help would be great

[daviddec]

Basically a tremolo control rocker pedal.       

[daviddec]

Bueller? 

Sorry just a little impatient and upping my request higher up the list.

[ashcat_lt]

I'm not a professional, but since nobody else around here has bothered...

I'm assuming (and this is a big assumption, correct if I'm wrong) that the speed of the motors that spin the speaker is determined by voltage.  If this is the case, then a "control voltage" is supplied to the motor.  This CV goes through the fast/slow switch, which chooses between a pair of voltage divider networks.  These are hopefully just a couple of resistors each, and would work basically like "preset knobs." 

If this is the case, then what you will want to do is interrupt the CV with a variable voltage divider. 

I'm hoping you've got a wire leading into the fast/slow switch.  You would basically cut this wire in half.  Connect one half to one of the wires connected to one of the pots in the volume pedal.  Connect the other half to the other wire on the same pot. 

Now check to make sure there isn't a huge amount of voltage ready to blast you into oblivion when you plug it in and put your foot on it.  Maybe somebody else could let us know if this is likely?

Now play with it (by rocking the pedal back and forth) and see if it speeds up/slows down when you expect it to.  If it does the opposite of what you think it should, switch those two wires around and you're done.

It appears to me that this pedal has a resistor on the way to ground.  This should stop the volume from ever actually hitting zero.  It should also keep the motor from stopping at the one extreme of the sweep.  If you actually want it to stop, replace this resistor with a piece of wire.

[Dan N]

Most fast/slow organ leslies have two little motors. The switch turns one off and the other on- or both off. Those little motors need to spin at a certain rpm to keep themselves cool. Run them slow and they will burn up.

[Dave_B]

I've seen conversations about using sewing machine motors.  These are speed controllable and I've seen them on the Internet for about $20 with a pedal, IIRC.  I don't know if they'd reliably do both speeds. 

[John Lyons]

Yeah, I was going to say that the two speeds are often controlled by two motors. Most likely the two speeds are going to work for morst situations but you may be able to modify the speeds enough to work better for you.
The motors are connected to pulleys and a rope like belt and then to a rotating drum which rotates over a speaker. Some have two speakers, a rotating horn and a low rotating speaker drum ( the speaker does not rotate, the enclosure above it spins and is shaped like a scoop to through the sound out) You don't want to make the horns too spuer slow (sounds lame anyway) because the motor is build for a certain speed. They are wound to spin at a certain speed.

What I would do is test it out at the two speeds. If they will work for you I would build a foot switch (or use the rocker if you don't want a volume control) to switch between the speeds. A 3PDT or DPDT would work.

John

[daviddec]

this leslie has just one motor (i'll put up photos as soon as I can) and so ashcat is right in that the switch changes the voltage to the motor, respective of the speed chosen.  I'm having problems with that switch too, I'll put up photos of this too. 

I'll try to do what ashcat suggested when I have more time.  Sorry bout not getting back sooner, internet was down here.

[Dave_B]

this leslie has just one motor (i'll put up photos as soon as I can) and so ashcat is right in that the switch changes the voltage to the motor, respective of the speed chosen.  I'm having problems with that switch too, I'll put up photos of this too. 

Are you sure about that voltage thing?  I've not seen a lot of Leslies, but the one's I have seen have one or two single-speed motors. 
As an example, I've got a single speed model.  It has four wires total.  Two for the speaker and two for the motor.  Is yours similar?  If it is, it sounds like a standard one-speed Leslie.

Regarding the switch, you'd probably want to use a triac or relay to switch the motors remotely, so you don't have 110v in your stompbox.

[daviddec]

and sorry about the double post, disregard the first one if possible.  I am a newbie to forums and building stuff yay!
sorry about these sizes, i can't change them for some reason. scroll on the bottom if neccessary. sorry 

I used to think the voltage was changed to speed or slow the motor, especially because when you speed it up, the tremolo effect ramps up (very cool if you know what I mean) and then when you change it to slow it halts back down to the slow speed, no gradual decay of speed (something I hope to do manually if I get the right info here  ).  So I thought it was voltage controlling, but then I saw that I have 6 wires coming from the leslie, two for speaker connections, two for a transformer, and two for the motor itself (check motor pics, I think this is right but I stand by if corrected.)

so here's the switches for the leslie.  as you can see one is the on/off switch, and the other is the speed switch.
x goes to hot power, y goes to an optional speaker, (i'm imagining a leslie cabinet [it says model 51 speaker on a sticker next to input]) and z goes to the leslie 5 pin connection.


x,y, and z lead to here, the "distribution frame" a power and speaker convergence point.  miscillaneous stuffa re labeled here
most important is the view of the leslie connection


so here's the pin, blurry but fine for what ails us. 


and now the motor.  my finger is pointing to a wheel that spins a rod that goes down through something?(another motor?) and then enters the motor part with magnets and a shit load of wires. this wheel speeds up considerably when the switch is activated, and slows back down when on slow.   The load of wires is where two cables are coming out of and into the connection pin.

perhaps better view here.


ok. 
so all that being said, I did not try ashcats suggestion as I think that the dual motor thing may be right. I'm thinking that the other motor? is constantly on and the fast switch turns on the transformer and speeds up the wheel to the pin to the gear, etc. 

I'd like to do as little damage to these old parts as they have stood the test of time so far, so perhaps it is something to keep in mind, and I do know I will need some parts (switches, case, etc.).  now that you knowledgable people have some more photos and info, hopefully you all can give me definite answers.  my end result is to have the rocker set the speed of the motor, and to have control of the leslie being on or off as well.

I look forward to it and thank you in advance.

[Dave_B]

What you've got are two motors stacked on top of each other.  That's a very typical setup.  Because the motors are small, it takes a few seconds for them to get up to speed, resulting in that 'ramping' sound.  You've got two wires for each motor, and the remaining two for the speaker.  When you wire it up, make sure that only one motor is turned on at a time.  By design, the 'fast' motor is always engaged, but it's only running when the Leslie is in fast mode. 

The spindle of the slow motor is designed to drop out of the way when it's not turned on.  Make sure the Leslie is mounted in such a way that it will do that.  I had mine upside down when I first got it and couldn't figure out why the spindle wouldn't disengage. 

The only way I can see you damaging it would be to have both motors on at the same time, or to have the slow motor touching the reduction wheel while the fast motor is running.

[daviddec]

I see.  The first few times I tried to speed it up it wouldn't either, I had it on it's back as well. 

So I'm wondering now if ramping down is possible with this setup, as well as if using a pot on the rocker pedal will be able to function as I hope.

If I wired a wire from each motor to a pin on the rocker's pot, and one going ground, would that function to give the motors a change in voltage? 

Also here are the photos that were once really huge, then really small, now managable.

[Quackzed]

it might be doable but!... if those are ac motors then you can't just change the resistance to change the speed, you'l end up burning out the motors ie. (slower) =more resistance = lower voltage/higher amperage wich will overheat the motors and burn em out... so something like a variac will work till you overheat the motors and kill em!
the good news is that the two motors are already set at good slow(chorale) and fast(vibrato) speeds and they will ramp up and ramp down.ramping down takes longer due to inertia( ) which gives it that authentic leslie sound! i doubt you'll really NEED other speed settings, as the effect is etherial enough that you dont need to play in sync like you do with delays etc... these things sound awesome!
*** but remember that your messing with wall voltages and 110v can kill your ass!***
... there should be a wing nut/bolt to adjust the small motor so it disengages the wheel when off.. make sure you try it with orientation it had in the organ and see if the small wheel will disengage and allow it to ramp down... if you want to use it on its side or upside down(i did) you'll have to add a spring and mess with the small motor springs etc... to give it just enough "play" to engage when on and disengage when off... takes some time and hair pulling. cause in organs some are on their side and won't go fast unless you use em on their side or add a spring and adjust 'em just so.
i have one and added a pen spring piece to get it to work right in record player orientation...ie not on it's side!

[Dave_B]

i have one and added a pen spring piece to get it to work right in record player orientation...ie not on it's side!

Quackzed, what are the odds that you have a photo of that?  You explained the pen spring to me a couple of months ago and I'm still not sure how you did it.

...not so good with written instructions. 

[Quackzed]

  i don't have any pictures sorry...
but basically, the two motors are arranged on either side of a metal plate(i'll try to use the posted pic for reference) if you remove the small motor (there are 2 thin bolts that go all the way through- keep all the washers etc straight make a diagram whatever) there is a small spring inside the small motor between the metal bar that rotates and engages the wheel and the diamond shaped cover(i think) on the opposite side that engages the wheel... basically its there to keep a balance so the sm motor will "slip" down when it rotates and "fall" up when its stopped(gravity) its inside the small motors mounting thing(rounded diamond shaped thing seen in the photos above, not the 2 bolts in the middle of the small motor, but the other two near the side that hold the diamond shaped thing and the motor mounts together) so you have to take the small motor apart to get to it... you can see the spring and you can add a bit of pen spring so that when you operate it in record player orientation( motors hanging down )
or "upside down" the spring keeps it(the motor shaft) from being too low to engage the wheel.
it's inside the small motor between the motor shaft and the diamond plate covering that side of the shaft!
and you have to orient the whole thing so it's upside down! so the board that holds the motors and the cheese wheel is on top and the motors hang down from it. like a table! it's a pita to get right !
hope this helps, i really should borrow a digital cam and do a photowalkthrough...
otherwise, putting the thing on its side a la bike wheel is how they are oriented inside organs and will probably work as intended without modification. hope this helps, feel free to ask questions if its too confusing.. i also cleaned up the small motor, rust etc... and oiled it b4 putting it back together!

[NoFi]

[daviddec]

So now that I know much more about the leslie and the way it funtions, am I to assume from the previous posts that what I'm trying to do, use a vol. pedal to control the speed of a leslie horn, will likely burn out the motor(s)?  Is that the consensus?

Or would a variac (I don't know much about how they work other than what wiki has to say about 'em)solve my problems?   Can you make it work so that when the pedal is "down" (like photo) only the slow motor is on and very slow, and when you press it up it increases the speed of the motor.  And then at the halfway point the fast motor engages and the rest of the pedal's sweep quickens the action?.

I know that on wurlitzers and other organs you can control the speed of the leslie speaker(s) with a knob (I've seen it placed to the players left) and organists can get cool sounds and percussive counterpoints if played well.   This is what I'd like to do but with a rocker pedal.  Or I'm thinking that the knob I speak of controls something else like a ...  please correct me if wrong, but I think it controls the speed of horn.

there has got to be way to do this, and maybe somebody already posted the answer elsewhere or here and I have missed it.

[Dave_B]

Unfortunately it sounds like you're going to have to experiment.  I've tried finding info on the Internet for trying out different motors and I've come up with very little.  I keep reading about sewing machine motors and a lot of times you can buy them with the speed pedal, like this one.  I don't really know how much effort it would take to make it work or if  you can get it to run at the standard speeds. 

If you want to save some cash, garage sales and Ebay are good sources for sewing maching parts. 

Wish I could help more.   

[Dave_B]

Ah, excellent photo.  Thanks, NoFi.   

[daviddec]

Well I appreciate the effort.  I'll let you know how it all comes out. 

I'll probably just use the existing settings but I do hope something like this is doable with some sort of hardware.