Using Relays to Engage Leslie Motors

[Craig V]

Hi,

I have a homebrew Leslie project that I am working on.  It has two motors, one fast and one slow.  They turn on when wall voltage is applied to either one.  I want to build a pedal to remotely control the motors, preferably fast, slow and off.

I've never used relays, and really to be honest don't know what they look like.  But I understand I can send a small amount of voltage to switch on high voltage through the motors. 

!) Would I need two relays?  One for fast, one for slow, then have no voltage from pedal to Leslie for off? 

2) What kind of specs should the relay(s) have?  I need wall voltage, 120 VAC, from one part, then I'd like to use a stompbox with 9 VDC to send voltage to the relay.  If a relay has a coil rating of 12VDC, would 9VDC not engage the relay?  Would this do the trick?  http://www.radioshack.com/product/index.jsp?productId=2062482&cp=&origkw=relay&kw=relay&parentPage=search

3) What kind of cable from pedal to Leslie would be needed?  A guitar cable, or speaker cable?  (1/4")

Thank you so much!  This has been a fun project so far, now it's getting close to firing it up!

[dansamp]

go to hammondb3organ.net and look up the stuff under leslie schematics there is lots of info there

the relays you can get from any online vendor or ebay
they usually run about $18.00 a non working leslie preamp just sold on ebay for over $120.00
the typical two speed motors are actually two separate motors and the relay just swtiches voltage from one to the other
or actually the slow motor engages the fast motor to slow it down
you can buy stuff from bborgan.com or you can get a custom made leslie pedal from vintagevibe.com

Dan...............

[Andre]

Craig,

I'm working on a leslie project too and I want to make it foot controlable.
Since I don't  want the relays switching current flow through the remote cable and want to use status LED's,
I have designed this circuit.



I have not yet build it and it will probably need some tweaking, but I think this will do the trick.
You will need some extra 9 or 12V DC powersupply.
The 2 circuits will be connected via some stereo 1/4" jack cable.


I hope this is of any help

André

[Primus]

http://www.users.bigpond.com/johnacollins/MotorControl.htm

The variale resistors set the various speeds you want. It can even inject current for dynamic breaking!

[Andre]

Craig,
I came up with my solution, but failed to answer your questions.

!) Would I need two relays?  One for fast, one for slow, then have no voltage from pedal to Leslie for off?

Yes, you would need 2 relays, 1 for switching slow/fast and 1 for switching power On/Off.

What kind of specs should the relay(s) have?

I think any 12V relay capable of switching 5A 120V AC will do. I have a Zettler 12V 5A 250V AC relay here that works fine with 9 volts.
The resistance of the relay coil is 283 ohms, so it will draw about 30 mA. This means 60mA with both relays engaged, so you would need to power it with
a power supply.

What kind of cable from pedal to Leslie would be needed?  A guitar cable, or speaker cable?  (1/4")

Since the relay coils are low impedance there is no need to use shielded wire, but you would need a three wire cable of course.


BTW Is your leslie a genuine leslie or a  leslie unit salvaged from an old organ?  (That's what mine is)

André

[NoFi]

Funny, i'm completing mine at the moment. It comes from an old organ and is nearly finished.



The schemo for the relay switching system i used can be found here (with a pdf layout but it will depend on your parts).
http://thebin.free.fr/Leslie/
It is super simple and works very well.

!) Would I need two relays?  One for fast, one for slow, then have no voltage from pedal to Leslie for off?

On this schema it's two relays, one to turn each motor on or off. Just like you say.
I used opto22 Solid State Relays, but they are BIG.

S2 and S3 just have to be connected to a stereo jack and then to a footswitch via any cable you want. A guitar cable will work.
The important thing is to keep the high voltage at the Leslie cab, and preferably not have it across the stage and at your toes.
I fitted this circuit in a box at the back of my cab.



The only thing i have not investigated yet is if i can power the leds in the footswitch directly from this circuit.
I'm using an old Ampeg footswitch at the moment with no leds. If it doesn't work, i'll just power the leds seperatly at the footswitch.

On one hand, this system demands less current because the relays are never on at the same time but the other hand Andre's idea of using one relay to switch both motors is possibly better because if for a reason or another the two motors get turned on at the same time, then you may get a nice burnt motor. Well at least it happened to me (they stayed on together for quite some time before i noticed).   



That was some time ago before i started building the cab, now it's all working again !

[Andre]

That sure looks great NoFi.  You really did a very nice job.
Please  show us the results when it's completely finished

Think I will use your cabinet's dimensions as an example for my yet to build cabinet.

Do you already have an amp to go with it?

André

[NoFi]

Thanks Andre, i took my time to do the best i could.
Dimensions are 64cm wide, 54 cm high, 38 cm deep. I suspect its a little smaller than the real Leslie/Fender cabs.

I use the cab with either one of my old tube 60 watters, Ampeg or Carlsbro. The cab is 64cm wide because that's the width of the Carlsbro head.

It's been a very interesting project so far,  woodworking + tolexing + painting + electronics + "mechanics" (i had to make one working motor assembly out of two different ones), and in the end... those unique sounds.

I'd really love to see pics of more homebrew Leslies.
Let us know if your switching circuit works !

It would be nice to have a circuit that allows adjusting of the fast speed. There are interesting sounds between the low and high speed settings, but you have to start and stop the motors every 5 seconds to get them lol.