Robin Sel
Posts: 5
Joined: Fri Feb 01, 2019 2:06 pm

Electric pulse scanner

Mon Feb 04, 2019 7:50 am

Hello,

I'm working on a project and has some trouble. I'm trying to scan when you push a button to higher a lift bridge. It works with a button like in the images below. Is there something to put between the button and the wires to capture when the button is pressed?

Image
Image
Image

I need to keep it simple with the wires and installation.
Does domeone has an idea hwo to do this.

Thanks

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davidcoton
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Location: Cambridge, UK

Re: Electric pulse scanner

Mon Feb 04, 2019 10:36 am

We need a lot more information about the wiring you want to monitor.
In particular, what voltage is used? What current will flow? And what is the button connected to?

I don't know if this project is mains voltage, or whether you are familiar with working with mains.
But please be aware that mistakes with mains can kill you or others, can burn property, and can destroy a Pi faster than you can say "Pi".
You must abide by your local wiring codes of practice. If you are not an electrician, you should consult one.
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pcmanbob
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Location: Mansfield UK

Re: Electric pulse scanner

Mon Feb 04, 2019 10:36 am

Hi.

Before anyone can help you we would need to know a lot more about the working voltages on the circuit you want to monitor.

Seeing as this is some sort of bridge control there may be legal ramifications if you make changes to bridge controls without proper authority.

and lastly you need to be fully qualified with relevant electrical qualifications before attempting this as mains voltages may be present and
120 or 240 V AC can and will kill you and start fires.
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Robin Sel
Posts: 5
Joined: Fri Feb 01, 2019 2:06 pm

Re: Electric pulse scanner

Wed Feb 06, 2019 3:24 pm

Do you have an idea to send a signal to the raspberry pi without messing with the cables?

pcmanbob
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Location: Mansfield UK

Re: Electric pulse scanner

Wed Feb 06, 2019 3:36 pm

You may be able to do it with a Digital Hall-Effect Sensor which will detect DC or AC current, but you would need to match the sensor to the voltage/current present in the wiring.
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Ruben432
Posts: 5
Joined: Mon Jan 21, 2019 9:17 am

Re: Electric pulse scanner

Wed Mar 13, 2019 9:43 am

pcmanbob wrote:
Wed Feb 06, 2019 3:36 pm
You may be able to do it with a Digital Hall-Effect Sensor which will detect DC or AC current, but you would need to match the sensor to the voltage/current present in the wiring.
Do I understand correctly that a Digital Hall-Effect Sensor will detect AC or DC without having to cut wires of the buttons it is measuring from?
Is there a minimal voltage that needs to be on the button before a Hall-Effect Sensor is able to measure it?

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Burngate
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Location: Berkshire UK Tralfamadore
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Re: Electric pulse scanner

Wed Mar 13, 2019 11:39 am

A Hall-effect sensor merely senses magnetic fields, in this case produced by electric current.
What size current is required to produce an output will depend on the particular sensor, how close it is to the wire, whether there's any magnetic material involved, such as ferrite, whether the wire is wrapped in a coil, ...

Brandon92
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Location: Netherlands

Re: Electric pulse scanner

Wed Mar 13, 2019 12:30 pm

Another option:
By the looks of it is the switch that you are using is modular. So if you can find a type number of the switching parts, you could place an additional switch next to the current one. And that switch can be use to detect if the button is pressed.

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Mortimer
Posts: 924
Joined: Sun Jun 10, 2012 3:57 pm

Re: Electric pulse scanner

Wed Mar 13, 2019 12:48 pm

Yup, what Brandon said.

With a new contact block for the switch available for only a handful of £'s (or €'s or $'s) it's a no brainer really.
https://uk.rs-online.com/web/p/contact- ... s/3310473/



All that is left is whether or not you can legally modify the equipment, i.e. do local regulations require you to use a qualified electrician?
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