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Single wire signal transmission

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hsieh

Sun Oct 03 2010, 02:44AM

Registered Member #1412 Joined: Thu Mar 27 2008, 04:07PM
Location: Taipei Taiwan
Posts: 278

Is it possible to transmit control signals with only 1 wire?(can't use earth to complete a circuit )

I want to use a similar system to control the electric motor of an electric powered control line model airplane(battery onboard).

something like this
http://en.wikipedia.org/wiki/Control_line
http://en.wikipedia.org/wiki/File:Strega7a.jpg

Those two wire may contact each other during flight so I can't use it to complete a circuit.
I tried to coat it with varnish(the paint manufacturer use to insulate transformers).But it dosen't work.I tried to add a third wire but thay tangled together.

ScotchTapeLord

Sun Oct 03 2010, 03:35AM

Registered Member #1875 Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635

Why not just use thin enameled wire twisted around the line or as the line?

hsieh

Sun Oct 03 2010, 03:44AM

Registered Member #1412 Joined: Thu Mar 27 2008, 04:07PM
Location: Taipei Taiwan
Posts: 278

ScotchTapeLord wrote ...

Why not just use thin enameled wire twisted around the line or as the line?

Thin copper wire is not strong enough.I'm now testing to twist it with the line.

However,if the wire thickness is increased,the air drag will increase a lot.So if I can use the original line to transmit the control signal,it's the best way.

Proud Mary

Sun Oct 03 2010, 08:51AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Multiplexing comes in a number of flavours, one of which is sure to meet your requirements.

Not having an earth return is no problem if you think of your single wire in terms of radio control.

Steve Conner

Sun Oct 03 2010, 10:04AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Yes, the only reliable way to transmit the signal down a single wire is using some sort of radio system. You need a high-frequency signal so it can couple back to earth capacitively and complete the circuit. You might as well buy an ordinary radio control set, and then it'll work just as well with no wires!

Years ago I remember seeing in a surplus store, reels of wire that were used in wire-guided anti-tank missiles. It was incredibly thin, strong, 4-core wire. Maybe you could get some of that?

hsieh

Mon Oct 04 2010, 01:50AM

Registered Member #1412 Joined: Thu Mar 27 2008, 04:07PM
Location: Taipei Taiwan
Posts: 278

Steve McConner wrote ...

Yes, the only reliable way to transmit the signal down a single wire is using some sort of radio system. You need a high-frequency signal so it can couple back to earth capacitively and complete the circuit. You might as well buy an ordinary radio control set, and then it'll work just as well with no wires!

Years ago I remember seeing in a surplus store, reels of wire that were used in wire-guided anti-tank missiles. It was incredibly thin, strong, 4-core wire. Maybe you could get some of that?

What is a surplus store?
I don't think It's possible(for amateur hobbist) to get this kind of wire in Taiwan.

radiotech

Mon Oct 04 2010, 07:03AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

Its called a G-Line, has a cone launcher at each end.

Steve Conner

Mon Oct 04 2010, 09:04AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

è¬æ˜•å“² wrote ...

What is a surplus store?
I don't think It's possible(for amateur hobbist) to get this kind of wire in Taiwan.

A surplus store is a shop that sells old electronic parts that are no longer needed by industry or the military. Ebay has made them more or less extinct.

Radiotech:

But you still need a radio to drive it.

Proud Mary

Mon Oct 04 2010, 10:40AM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Years ago I remember seeing in a surplus store, reels of wire that were used in wire-guided anti-tank missiles. It was incredibly thin, strong, 4-core wire. Maybe you could get some of that?

During the Second World War, the Germans developed multi-wire tactical missile guidance when radio control proved vulnerable to British jamming.

I too saw the four-core wire for sale in army surplus outlets some years ago, and believe it came from the 1970s MILAN missile system.

radiotech

Mon Oct 04 2010, 04:40PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

Since this is for a teathered model aircraft of some sort why not use the teather-wie as a taut acousta-mechanical coupler. Just rig a tin-can telephone from ground to the plane. Far fetched, oh yes, but the signals could be any grouping of vibrations. And at the plane end, a tuning fork activated servo. No one could radio-jam it as seems to be the mischief afoot with model flyers sometimes.

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