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Thread: Relay Question

  1. Relay Question

    I have a need to be able to control 4 or 5 relays from a Eee PC, USB ports only. The load will be from 2 different sources 6 and 12 (7amps) volt Gel Batteries. They will be powering 12 volt 2 amp motors and turning on and off other lower power options. The 6 volt would be used to entergize the relays. I need to control them from a C# program. I know phidgets has a 4 and a 8 relay board that would work, but trying to figure out if there are better and cheaper options. I was also wondering if i can use a usb to serial cable to control some of the serial relay options out there.

    I thought i read that someone use a servo controller to control a relay is that possible if so how. my project also has a Polou 8 servo contoller, i am controlling it from a USB 2 Serial cable now, so is this an option?

    thanks for any help

    tim

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    Re: Relay Question

    Unless you need additional inputs or outputs then the relay cards are probably your best bet. If you do need some inputs then an Arduino or similar microcontroller would work great.
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    Re: Relay Question

    Quote Originally Posted by tbh726 View Post
    I thought i read that someone use a servo controller to control a relay is that possible if so how. my project also has a Polou 8 servo contoller, i am controlling it from a USB 2 Serial cable now, so is this an option?

    Any of these can be controlled from a servo controller:

    http://www.trossenrobotics.com/store...led-Relay.aspx
    http://www.trossenrobotics.com/store...10A-relay.aspx
    http://www.trossenrobotics.com/store...-RC-100X-.aspx

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    Re: Relay Question

    I never new such a beast existed. You learn something every day!
    "If A is a success in life, then A equals x plus y plus z. Work is x; y is play; and z is keeping your mouth shut."
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  5. Re: Relay Question

    So then for the ones I would be able to control via a servo controller I would just send a "Position" move and that turns it on? If does that me if I send a second "Position" it would turn it off? I am interested in knowing what i can do, but for my project i need 4 to 8 relays to be usable. if i am pulling 12 volts per motor, i think they are 1 or 2 amps and the supply will be a 12 volt 7 amp gel battery does it matter which phidgets relay I use?

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    Re: Relay Question

    I believe the positions are based on a joystick, so center position or 1500...with phidgets I believe its set motor position 113 or so...would turn it off, and going to one extreme or the other turns it on...thats atleast how the ones that I have work.

    Hope this helps.

    DB

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    Re: Relay Question

    >> and the supply will be a 12 volt 7 amp gel battery

    You might already know this, but just to make sure...

    That's not a "7 amp" battery. It's a 7 A/h or 7 Amp/Hour battery. That means that, in theory, you could draw 1A for 7hrs before it was _completely dead_. In practice, it's much less. However: you can pull well over 300A from it in a direct short. My stalled drill motors will routinely pull 120A for a short period of time from it.

    Yes - R/C relays are "all or nothing" affairs. Usually a signal equating to 45deg + will trip them on, 0 or 45 deg - turning them off. The big question is: What are your motors when they're *stalled*. You didn't mention what specific motors they are, I don't believe.
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    Talking Re: Relay Question

    Let's say, um,... one or two RC tank airsoft gun motors at 4.8 to 6V NiMH, for example....
    Could such a circuit be used on one channel to switch two devices on? -45deg=motor1 on, 0=off, +45deg=motor2 on??

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    Re: Relay Question

    Nope! The relay only knows how to do one thing. The switch is on or the switch is off. No "trinary computing" allowed here. A large enough relay could drive both motors simultaneously though. Just not selectively.

    Two R/C-type relays could be wired to two separate servo channels on your servo controller and do something like that though...

    As a postscript: You don't want to run those guns at 6v. They'll shoot like ick. Run 'em at 9v at least.
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    Re: Relay Question

    tbh726.. this one would do 2 motors at once.. they have larger ones too.

    mannyr7.. here's one that should do what you were suggesting..

    http://www.robotmarketplace.com/prod...TD-RCE220.html

    look over the data sheet on the web site..
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