How far would you run the wire until you started to get uncomfortable?
HeneryH:
- Using twisted pair to wire to a button to detect a button press on a NO button. Pull up on detect wire then button grounds it.
How far would you run the wire until you started to get uncomfortable?
I'd get uncomfortable really quickly tbh. That being said, if you use two separate and isolated power sources (one at the button and one wherever the other end of the cable is) AND have electronics to convert the button single ended signal into a differential-high impedance signal, you can run wires nearly as long as you want.
Here's a schematic of what I'm talking about:
The reason why you want a differential signal is because it easily rejects noise and it's power efficient. Doing a normal single ended wiring job with a pullup will not work as well since the total resistance of the wires will become substantial as they increase in length.
I have nothing at the remote location except what I run to it from the central area. It is open yard with a gate at the far end.
The area I am referring to is a remote gate with a magnetic lock. I already have the 12vdc running to the mag-lock. I switch the 12vdc mag-lock power supply via one of these Qwiic Quad Relay - SPX-15032 - SparkFun Electronics .
I just need to add an 'exit' button so people can get out with a simple button press.
HeneryH:
- Outdoors
- Buried about 6 inches
- Re purposing cat6 network cable
- Using twisted pair to wire to a button to detect a button press on a NO button. Pull up on detect wire then button grounds it.
How far would you run the wire until you started to get uncomfortable?
I guess you don't even have the wire or you would have tested it. I have runs of 74 feet some on top of ground, some of it in steel pipe under driveway and some of it going up a wooden pole to a device. Total of about 75 feet.
Paul
Paul_KD7HB:
I guess you don't even have the wire or you would have tested it. I have runs of 74 feet some on top of ground, some of it in steel pipe under driveway and some of it going up a wooden pole to a device. Total of about 75 feet.Paul
Quite an assumption you made there... Yes, I have the wire and it is already installed. Previously is was used with a dedicated keypad system that has since broken. I am considering using a Pi/Arduino based system to replace the keypad system and thus my question here... I'd rather take advantage of any knowledge here rather than design, procure and install a system then test it. Even if I did test it and got positive results at the outset, it might be on the margins of safety for the equipment as environment varies.
HeneryH:
Quite an assumption you made there... Yes, I have the wire and it is already installed. Previously is was used with a dedicated keypad system that has since broken. I am considering using a Pi/Arduino based system to replace the keypad system and thus my question here... I'd rather take advantage of any knowledge here rather than design, procure and install a system then test it. Even if I did test it and got positive results at the outset, it might be on the margins of safety for the equipment as environment varies.
Yes, it was. I wondered why you had not just connected it up and tried it!
Do you have assurance the existing wire is still in good shape? Do you have gophers in your yard? They love to chew on wire insulation? Have you connected pairs at the far end and checked them with an ohmmeter?
Was the keypad system sending data back to the origin, or was the control right at the gate? If it worked with a remote controller, it will most likely work with a 5 volt Arduino system.
Paul
The keypad had keys that were mechanically sticking making proper PIN entry difficult.
The current electrical wires are sound.
My real question is this...
If you had perfect condition network cable buried under 6" of dirt, how long of a run are you comfortable running for an arduino NO switch using a pull-up digital pin being grounded by the button switch?
You keep saying 'test it' but I am really interested in this communities thoughts on the hidden risks/problems that might arise even if a preliminary simple test works.
There is no clear or simple answer to your question. Testing is the ONLY option, and with underground cabling, expect to test at regular intervals.
If water or moisture can ever get into the wiring, it is just a matter of time before the system fails. Other problems with long runs of cable are outside electrical interference from other current carrying wires or lightning (yes, even underground), cable capacitance limiting signal speed and causing malfunctions, gopher teeth, gardener's shovels, etc.
HeneryH:
The keypad had keys that were mechanically sticking making proper PIN entry difficult.The current electrical wires are sound.
My real question is this...
If you had perfect condition network cable buried under 6" of dirt, how long of a run are you comfortable running for an arduino NO switch using a pull-up digital pin being grounded by the button switch?
You keep saying 'test it' but I am really interested in this communities thoughts on the hidden risks/problems that might arise even if a preliminary simple test works.
As a famous person who ran for President said "what difference does it make, anyway?". If we said 1,000 feet was ok, or said 10 feet was bad, How does that apply to your situation? Are you going to hold the forum responsible for you wires?
Paul
Paul, you are ridiculous and clearly have a bug up your arse about this thread or me.
It would matter because if there was concern raised here about running wires, I would use a wireless solution. If the community generally thought it was fine, I would use the wires.
Isn't that the whole point of a forum? Ask questions and gather peer advise to then determine a final solution?
How long?
I work in telecoms, the cable from telephone exchanges to telephones run underground and overhead, they can be several kilometres long. Works just fine. Across your yard to your gate, a mere nothing!
The area I am referring to is a remote gate with a magnetic lock. I already have the 12vdc running to the mag-lock. I switch the 12vdc mag-lock power supply via one of these Qwiic Quad Relay - SPX-15032 - SparkFun Electronics .
I just need to add an 'exit' button so people can get out with a simple button press.
That said you need to protect the inputs to the Arduino against voltage spikes and noise. I would be concerned about spikes originating from the drive to the magnetic lock as well as external noise. It probably requires experimentation but maybe a 1k resistor in series with each wire at the Arduino end and a pair of reverse biased Schottky diodes at the input pin. One diode from 0v to the pin, the other from the pin to the Arduino supply (the actual supply to the chip after any regulator, not the input to the board).
You might also consider reducing any spikes from the magnetic lock with a reverse biased diode across the magnet coil, to absorb the back emf when it is released (there might be one already).
Thank you Perry