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designing a relay circuit

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keysnleslie

New Member
Hi,Great forum thanx for being here! I am using a Leslie (rotating) speaker with an electronic keyboard.The rotating mechanism has a 120 VAC assembly consisting of a small motor piggybacked on a larger motor.In its original incarnation there was a relay within the audio amplifier that afforded a quiet means of switching between motors,or speeds as they are known.Since that amplifier is long gone,I have been using a simple DPDT footswitch.This works fine for control,however when I switch speeds there is a very audible "POP" through the speaker and sometimes it can be heard through the main PA system,totally unacceptable. I have enough electronic ability to construct a relay system but do not know how to select the correct relay. I would like to possibly use 9-12VDC as the activating voltage so that I may experiment with the use of a 9 volt battery,but will initially construct it with a 9 volt transformer and the nessesary filter pack if need be. Thank You, :? Keys
 

Klaus

New Member
Your post is the first instant I ever read about Leslie speakers - So, my knowledge about these is nil :)
However, the way I understand it you want to switch an AC motor quietly so there is no sound from the relay arcing through the speakers?
Have you tried a solid state relay? These switch on zero crossing of the AC waveform and would cause nil interferance. You can control them with a 9V battery operated foot switch. Keep that switch circuit totally isolated from your amplifier/ speaker wiring.
 

keysnleslie

New Member
keysnleslie said:
Hi,Great forum thanx for being here! I am using a Leslie (rotating) speaker with an electronic keyboard.The rotating mechanism has a 120 VAC assembly consisting of a small motor piggybacked on a larger motor.In its original incarnation there was a relay within the audio amplifier that afforded a quiet means of switching between motors,or speeds as they are known.Since that amplifier is long gone,I have been using a simple DPDT footswitch.This works fine for control,however when I switch speeds there is a very audible "POP" through the speaker and sometimes it can be heard through the main PA system,totally unacceptable. I have enough electronic ability to construct a relay system but do not know how to select the correct relay. I would like to possibly use 9-12VDC as the activating voltage so that I may experiment with the use of a 9 volt battery,but will initially construct it with a 9 volt transformer and the nessesary filter pack if need be. Thank You, :? Keys
Music is the brandy of the damned,Hell is full of musical amateurs:[/quote]
 

john1

Active Member
Taken from:
http://www.dairiki.org/HammondWiki/Leslie

Today's Leslie cabinets made by Hammond/Suzuki use a single
motor with a motor controller card to determine fast, slow or
off. ScottHampton (Hamptone) and BobSchleicher (tonewheel.com)
manufacture aftermarket SolidStateRelays that eliminate relay
click and, in the case of the Schleicher relay, allow
three-speed operation from the console.


Klaus's suggestion of using solid state relays is perfectly
sound, and from the excerpt above, it looks like this has
already been adopted by some manufacturers of this type of
speaker enclosure.

They virtually eliminate the click by switching as the supply
crosses the zero point, mechanical relays are not fast enough
to do this.

Such devices are readily available, and not expensive.

Regards, John :)
 
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