Electronics question - can I run current like this?

[wackychimp]

So I've got a pretty simple idea but since my knowledge if electronics is limited, I wanted to get some feedback first.

I want to run a simple momentary switch on a long cable (like 30ft) from a little motor powered by 2 D batteries. Push the button, motor runs. I have an old phone cord that's a good length. Can I run electricity through this without starting a fire over prolonged use?

I realize at some point a copper cable is a copper cable whether you're sending voice/data impulses over it or making short electric connections. I just don't want to overload the cable... if that's even possible with the 2 D batteries.

Thoughts/recommendations?

Thanks!

 

[whoever]

Phone cord is a little thin for such a long run. Thin guage speaker wire would be a better choice as voltage drops over a run due to resistance. The bigger the conductor, the less resistance.

 

[exoray]

The short of it, it's not he best choice, but for all practical purposes it will work just fine for your application...

 

[whoever]

The short of it, it's not he best choice, but for all practical purposes it will work just fine for your application...

Over that distance, I would expect the voltage drop to be such with using phone wire that the motor would run slow.. If that is not a concern then go for it.

 

[wackychimp]

Great! I may give it a shot since this phone cord has been sitting in my workbench drawer for like 6 years. Then go pick up some speaker wire if I'm not getting enough juice to it.

I was mostly worried about overloading it.

Thanks guys!

 

[whoever]

Overloading it is more to do with amperage draw than voltage. Are you wiring the batteries in parallel or series?

 

[wackychimp]

Hmmm... I'm hacking into a Halloween prop that takes 2 D batteries so I can set it off by push button. Don't know if it's parallel or series though. Any way to tell?

 

[whoever]

Hmmm... I'm hacking into a Halloween prop that takes 2 D batteries so I can set it off by push button. Don't know if it's parallel or series though. Any way to tell?

I would suspect it to be run in series for a total of 3v, which means the amp draw requirement would be low. If it is a battery holder part of the toy, it is likely completing the series circuit as part of the holder design.

 

[exoray]

Over that distance, I would expect the voltage drop to be such with using phone wire that the motor would run slow.. If that is not a concern then go for it.

No need to suspect anything as you are incorrect, the voltage drop would be minimal over 30 feet of phone wire, nearly insignificant... Flat modular phone cable uses 26AWG wires, the resistance for 26AWG wire is .0480/foot or a whopping 1.44Ω over 30 feet literally hardly anything to worry about for most applications including this one... The bigger concern would be the current requirements but even then if the device is designed to run off two D batteries hardly a concern at all in this application, as it's highly unlikely it draws enough current to see any real adverse effects with 26AWG wire as it can pretty much handle anything 2 D batteries can toss at it...

Sometimes it's best to step back from the 'Tim the Tool-man' mentality of excessive overkill for basic simple task...

 

[wackychimp]

Overkill is good. Did I mention I was going to hook it up to a car battery after my D cell tests? LOL!


My thanks to both of you for the advice. Exoray I was lost on about half of what you posted above, but since I've been running your super excellent proton pack control board for two years now, I know you know what's what.

I'm just glad to hear that fire is unlikely.
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[Mr.Engineer]

Oops. I was about to suggest a RF remote control instead, which you can activate from about 100 meters or so.....

 

[exoray]

Oops. I was about to suggest a RF remote control instead, which you can activate from about 100 meters or so.....

Always an option, and they are dirt cheap now, a complete already built RC with a nice key fob 1 channel remote and a relayed receiver can be had for about $10 now... It's crazy how cheap they have become... The units can even be gutted out of cheap remote control toys, distance will vary but 30 feet is well within most of the toy RC units range...

 

[nexnox]

Overkill is good. Did I mention I was going to hook it up to a car battery after my D cell tests? LOL!


My thanks to both of you for the advice. Exoray I was lost on about half of what you posted above, but since I've been running your super excellent proton pack control board for two years now, I know you know what's what.

I'm just glad to hear that fire is unlikely.
_________________________________

Sent from my Droid using Tapatalk

if you don't want to go wireless, use an NPN transistor to keep the batteries near the motor. With a transistor you don't need to worry about the control wires as you wont be putting your load down them. if you are going to use car batteries, use a transistor to trigger the coil on a relay.

 

[exoray]

if you don't want to go wireless, use an NPN transistor to keep the batteries near the motor. With a transistor you don't need to worry about the control wires as you wont be putting your load down them. if you are going to use car batteries, use a transistor to trigger the coil on a relay.

WAY too overkill, I can't follow your logic either, "a transistor to trigger the coil on a relay" why? Really the only time you would be doing that is if the your trigger source couldn't source enough juice to trigger the relay itself and I don't see that being the case with a manual switch on a car battery...

As I have said 30 feet of wire is absolutely not an issue for this application...

So KIS (Keep It Simple)