Need help with relays for Leslie

[SonicVI]

I'm building a homemade Leslie from a unit salvaged from a trashed Thomas Organ. I need to make a switching box but I don't have much experience with relays. I know how they work basically, and I have a schematic, but I don't really know enough about them to know what the most appropriate part is that I should get.  I just need a couple of SPDTs with 12V coil voltage.   Could anybody recommend a suitable part number from Mouser for switching the 120VAC motors and the speakers?

This is the schematic I'll be using.

[R.G.]

Look at the motors and find their ratings plate, which should tell you their current rating.

Pick relays rated for at least this much **AC** current into an **inductive** or motor load, and 120, preferably 240Vac voltage.

If you can post pictures of the ratings plate, I can help.

The physical setup for mounting the relays is as important as the ratings. If you need to do a direct replacement for what's the, OK. But consider using relays and sockets that will make relay replacement easy one day, as motors are a difficult load to run well with relays in the long run.

[SonicVI]

Here are the labels on the motors. Hopefully you can make them out.

http://i100.photobucket.com/albums/m23/sonicvi/060F7D1D-5130-4CEB-A208-7C50DFFE9EEC-5365-000004EF5014A91D.jpg
http://i100.photobucket.com/albums/m23/sonicvi/9ECD6B41-F5B2-439D-A6BB-BDF1953D6928-5365-000004EF58AE15C0.jpg

[R.G.]

Well, I guess rating labels are better than the used to be. 

Not a word about the current. OK.

You going to do this on PCB or perfboard?

I'm about to take back my advice from earlier. You can get Omron G2RL-1-DC12 relays from Mouser for $2.05 each. These have solder pins. It may be more cost efficent to buy spare relays and tape them inside the box than to buy sockets.

[SonicVI]

It'll be perfboard most likely.

I've been searching Google for specs for Leslie motors and haven't had any luck.

Thanks very much for the advice, RG.   I'll check out your recommendation!

[R.G.]

I went with most amperes switched per dollar. The G2 series I mentioned is rated for something like 100,000 operations switching 10A. The motors you show are shaded-pole motors and not much real current, probably well under 5A.

You could measure the motor run current and know, but I figure 10A is OK.

Ideally, you'd use a different relay for K1 and K2, as the motor is fine with large AC signals for power. The speakers will have small signals a lot, and some relays have minimum voltage and current requirements, as small voltages and current may not cut through the inevitable crud on the contacts.  This gets worse with age. But with $2 relays, buy some spares.

[SonicVI]

Gotcha, thanks, I will do that.

Another relay-ignorant question. The specs say the coil current is 33mA. Is this how much current the relay draws? So, if I am using two of them then a .5A power transformer, say, would be plenty?

[PRR]

I can't picture these motors sucking even 1 Amp.

Agree that motors are brutal, 10A relays are cheap-enough, little need to shave an "exact" rating.

We might sharpen the pencil if the relay coils had to be battery powered, so we needed the smallest coil (forcing a small clacker of low Amps rating). But a Leslie can't stray far from a wall outlet, SonicVI says a 0.5A tranny is handy, which is more than enuff for many 0.033A coils.

[SonicVI]

I finished this up a couple of weeks ago and the relays RG suggested work beautifully. Thanks again RG!

[R.G.]

Nice work.
Glad I could help.

[tubegeek]

Very sweet. Is there more info about your project here on the site? I'd love to see how the Thomas Organ setup looked.

[SonicVI]

It started here 
The Thomas is the one up on its side. The speakers were already gone when I found this heap, but the leslie unit was still there, just missing the belt.  The amp was solid state unfortunately.
I also found an Accutronics reverb tank, some TDK inductors and 8 socketed metal can RCA CA3080s.


I cleaned up the motors, bought a belt, a Weber Thames 10" ceramic speaker, and built a cabinet and this control box.



and a poorly played demo.

[tubegeek]

Wow! Lazarus, back from the dead!

Nicely done!