# Is it possible to wirelessly "connect" a circuit, for small voltages?

#### measuregreater

Joined Oct 2, 2018
7
Let me preface this by saying I am a complete novice when it comes to electronics. Hence why I am here. So please be nice, even if I'm talking absolute nonsense.

I have a simple query. Is there any way to wirelessly connect two ends of a circuit to give a readout on a multimeter?

I have attached a simple diagram of a multimeter connected to a 1.5v battery, showing what I mean.

Is there any way to bridge that gap to get a readout? Is it possible to do this with the following: Analogue to digital conversion - Wireless Transmission - digital to analogue conversion or possibly an easier way?

I'm looking for the simplest solution.

S

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#### ericgibbs

Joined Jan 29, 2010
18,055
hi m,
Welcome to AAC.
What is the distance of the gap.?
E

#### measuregreater

Joined Oct 2, 2018
7
hi m,
Welcome to AAC.
What is the distance of the gap.?
E
Hi Eric, Thanks.

As far as possible really, anything up to around 10km.

Cheers,

S

#### WBahn

Joined Mar 31, 2012
29,175
Just to be sure I've got this straight -- you want to wireless connect a 1.5 V DC circuit across a 10,000 meter gap?

Let's take a step back. WHY do you want to do this? What problem is it that you are trying to solve?

#### measuregreater

Joined Oct 2, 2018
7
Just to be sure I've got this straight -- you want to wireless connect a 1.5 V DC circuit across a 10,000 meter gap?

Let's take a step back. WHY do you want to do this? What problem is it that you are trying to solve?
I'm involved in cathodic potential measurements on subsea pipelines. At present, when doing shallow water surveys we need to make a hard wire connection between a multimeter and the pipeline. One lead of a multimeter is connected to an passive electrode. The other is connected to the pipeline test point on the beach, through a small enamelled copper wire, running out the back of a boat, which is usually about 10km long. I am curious to know whether it's theoretically possible to do away with the wire and transmit the signal wirelessly.

Thanks,

S

#### WBahn

Joined Mar 31, 2012
29,175
I'm involved in cathodic potential measurements on subsea pipelines. At present, when doing shallow water surveys we need to make a hard wire connection between a multimeter and the pipeline. One lead of a multimeter is connected to an passive electrode. The other is connected to the pipeline test point on the beach, through a small enamelled copper wire, running out the back of a boat, which is usually about 10km long. I am curious to know whether it's theoretically possible to do away with the wire and transmit the signal wirelessly.

Thanks,

S
I don't think so.

#### measuregreater

Joined Oct 2, 2018
7
I don't think so.
Could you tell me why you think it wouldn't work?

#### Alec_t

Joined Sep 17, 2013
13,795
Because radio waves travel very poorly through water.

#### measuregreater

Joined Oct 2, 2018
7
Because radio waves travel very poorly through water.
Hi,

It would not be through water. It would be from a boat to shore.

S

#### ericgibbs

Joined Jan 29, 2010
18,055
hi m,
Is it like this image.?
E

#### BobaMosfet

Joined Jul 1, 2009
2,082
If you are not transmitting through water, but just through air- this is what standard radio communications does. No need to reinvent the wheel. You just need an AM or FM signal at a given base frequency for your carrier that you can transmit and receive on at a high-enough wattage to make the distance.

#### ericgibbs

Joined Jan 29, 2010
18,055
hi,
The problem is that you are using the enamelled copper wire as part of a circuit for measuring a low analog voltage, its a closed 'current' loop.
Break that loop and you have no current path.
E

#### measuregreater

Joined Oct 2, 2018
7
hi,
The problem is that you are using the enamelled copper wire as part of a circuit for measuring a low analog voltage, its a closed 'current' loop.
Break that loop and you have no current path.
E
Your diagram is correct except that the connection on the beach is physically connected to the pipe, not a cathode.

Yes, I'm starting to realise that once you break the physical connection, there is no current flow and there would be no way to simulate that.

#### joeyd999

Joined Jun 6, 2011
4,974
I'm involved in cathodic potential measurements on subsea pipelines.
Small world! My BSEE senior project, many hundreds of years ago, was remote cathodic potential measurements on overland pipelines.

Good luck.

#### measuregreater

Joined Oct 2, 2018
7
Thanks for your help everyone.

#### ebp

Joined Feb 8, 2018
2,332
When you say "survey" - are you working your way along the path of the pipeline, making measurements from near shore to 10 km out? I'm assuming from the voltage mentioned the protection current is off during the survey. Copper-copper sulfate half-cell electrode?