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Thread: Leslie motor/power/speed switch schematic

  1. #1
    pez
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    Leslie motor/power/speed switch schematic

    Hey everyone, I've got a goal to build a 1x12" leslie type cabinet with a stationary speaker and a rotating drum. It would be unpowered (the speaker that is) so I can use it as an extension cabinet for my combo amp. I'm sure I can assemble the general structure and mechanism of the unit, but I lack technical information and experience to wire the motors to the power supply and speed switching system. I would like a 2 button footswitch, one for fast/slow and one for on/off.

    I thought it might be easiest to buy a 2 speed leslie motor off ebay for authenticity of speed and ramp time etc...
    As I understand it, (and please correct me if I'm wrong) these are ac motors. I've read some things about using the footswitch to control mechanical relays which sends power to one of the two motors depending on the position of the switch. I suppose then a second relay could be added to control the on/off function.

    How does one get power from the wall to the relays? Is there another component between there? I think transformers are used only in dc power applications correct? I think I would like a master power switch on the cabinet also.

    Could anyone provide a detailed diagram of the connections necessary to make this rig work? Component specs? Even part #'s possibly?

    Does anyone know how the system to stop the rotor facing a certain direction might work? It would be beneficial to have a consistent sound on stage when the system is off. There are models made by motion sound and leslie that do this.

    Wow! I have a lot of questions! I know I can do this with a little information about how the components are supposed to work together. That's where you guys come in. Thanks in advance for any advice or info you've got!

    Shael

  2. #2
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    I did this very thing with an old MTI Rotophaser, that someone gave to me.
    the unit is basically the unpowered top half of a leslie. When I got it, it was in bad shape. I wired it up the way I thought it should be wired. I installed a 12v powersupply & a relay rated to handle the current draw of the motors. This I used to switch speeds without having to run 120 ac to the footswitch (sounded dangerous to me!) I used the same power supply to control the bypass relay. you just wire it to bypass the leslie and connect to the amp spkr when not in use. wiring a relay is basically the same as wiring a switch. there should be a diagram with or on the relay itself showing connections. the relays I used are rated @ 12vdc control voltage & 4 amps on the contacts. Its fairly easy if you plan it out before hand on paper.
    good luck

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    I have one in my basement that I wired up too many years ago,so I dont remember exactly,but I didnt use any relays,just a two speed motor,a couple of stomp switches one for fast one for slow,just turn them both to "off" and you wont need a third "off" switch,all wired directly to the wall outlet plug.I would have to tear it open to see exactly what I did,but I dont recall having any difficulty,just get the motor and you should be able to figure it out,it was pretty straight-forward.When looking for the motor,be aware that there are two different style 2 speed motors,one is designed to be oriented vertically,the other horizontally,in other words you will end up with your speaker mounted face up or pointed forward as a normal speaker in a cab would be,dependant on which motor you have,and they have to be oriented in the designated position.Mine has the speaker facing up,and I dont see any need to have the drum oriented in any particular direction,but that sounds like it might be difficult to arrange.The cab I built has openings on all four sides at the top half of the cab "walls".

  4. #4
    pez
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    mbailey: were the motors you used ac or dc? What kind of power supply did you use?

    I'm inclined to agree with you about running the full current through the footswitch. I think the extra components and trouble are worth keeping all the juice inside the cabinet.

  5. #5
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    The actual leslies use AC motors. Transformers are used for AC only, by the way (unless to block DC in certain circuits with special transformers, i.e. Fender Champ ). The speed of the motor is not set by the AC voltage, but by the powerline frequency. The slow motor or fast motor will spin the same speed no matter how much voltage you give them, until there's too little to energize the stator (rusty on motor electronics, but that sounds right). I have a bunch of single-speed leslies, and they all take 120v, 60hz as the supply, wired direct to the motor. You could just put push-on-push-off switches in the hot lead (with a fuse, preferably). No relays really necessary. I've never turned both motors on at once (mine are all single speed) so I'm not sure if that's something to avoid when you wire your control pedal/panel. Good luck!

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    leslie motor power and speed switching schematic

    There is no power getting to slow motors. The motors work fine but there is no power getting to the AC outlet where the motors plug in.

  7. #7
    gsr
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    I have built a few "leslie" style speaker cabinets for guitar and IME the ramp up/down that is so cool with Hammond organs is not so important with guitar. To my ears, if you can get the drum to spin real slow, you can get an effect similar to when Jimi has his solo panning back and forth from left to right. Also, you can get a real nice "Badge" sound with it set medium fast and having a stomp switch to go between wet and dry signal. A simple way to do a ramp up is to use a momentary switch (Off/On). It kind of works like a gas pedal. In fact I thought about installing it in an old wah shell. Some have suggested a sewing machine foot pedal.

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