electricity intercepter?

[JonaChan]

hey, I was wondering if there's any type of electronic component that can cut off or re-connect an electric wired signal when directed. I'm planning on making a device that can cut off an Ethernet signal at a certain time, given a schedule or a timer. For example, at 8:00 pm the cable will be cut off and at 8:00 am the cable will be reconnected. I was thinking of doing it mechanically, with a rc car servo or something that would actually unplug or plug in the cable robotically, but am now having second thoughts, considering it might be easier with an aurdino or raspberry pi digitally. Any electronic components that can stop electricity from flowing through a cable?

thanks, community, i have a lot of faith in you and it hasn't been let down yet.

 

 

I'm a somewhat beginner with this type of electronics, but i know common and basic terms about transistors, amplifiers, capacitors, breadboards, etc, but have never actually done a real DIY project that involves stuff like this.

so take it easy on the smart-people talk, haha.

 

 

Also, if you have the time, I have a little side question about display cables. 

what if there was a little device that plugged in between a display cable and the display output that would act like nothing was there until given a wireless command to activate, which would then intercept the display signal and replace it with its own, technically "hacking" or hijacking the display until disabled, which would allow the output access to the monitor again. Maybe a heavily modified raspberry pi?

 

peace

[Hackentosher]

Sounds like you want a bajillion port relay and an arduino.

[JonaChan]

Just now, Hackentosher said:

Sounds like you want a bajillion port relay and an arduino.

about the display thing or my main question?

[Hackentosher]

1 minute ago, JonaChan said:

about the display thing or my main question?

You could do both with an arduino and a relay, but why the hell would you want to do that to someone's monitor?

[JonaChan]

Just now, Hackentosher said:

You could do both with an arduino and a relay, but why the hell would you want to do that to someone's monitor?

honestly, I really don't know. Just the thought of being able to hack any tv or monitor is really cool, would like that power in my hands haha.

any idea where to get a relay for Ethernet, or any guides? where do i start?

[Hackentosher]

Just now, JonaChan said:

honestly, I really don't know. Just the thought of being able to hack any tv or monitor is really cool, would like that power in my hands haha.

any idea where to get a relay for Ethernet, or any guides? where do i start?

For the ethernet thing, I'd get an 8 port relay (one port for each wire) and wire it so that each gate is controlled by one pin on the arduino (may need another relay to supply enough current to your big relay, relay-ception lol) then make an cat5 in and a cat 5 out. 

[JonaChan]

Just now, Hackentosher said:

For the ethernet thing, I'd get an 8 port relay (one port for each wire) and wire it so that each gate is controlled by one pin on the arduino (may need another relay to supply enough current to your big relay, relay-ception lol) then make an cat5 in and a cat 5 out. 

alright, i hate to ask more, so let me know if you just want a "best answer" or solved. anyway, does a relay just switch between inputs and outputs kinda like an airplane terminal? not quite sure what you mean. (my bad)

[dany_boy]

3 minutes ago, JonaChan said:

alright, i hate to ask more, so let me know if you just want a "best answer" or solved. anyway, does a relay just switch between inputs and outputs kinda like an airplane terminal? not quite sure what you mean. (my bad)

A relay is just a switch that you can control with electricity (either mechanically or electronically). Think of it as a switch that turns on/off with an electric current instead of your finger

[Hackentosher]

A relay is an electrically controlled switch. Basically the switch can be open if there is no current flowing through the input side of the relay, and closed if there is.

[JonaChan]

Just now, Hackentosher said:

A relay is an electrically controlled switch. Basically the switch can be open if there is no current flowing through the input side of the relay, and closed if there is.

 

1 minute ago, dany_boy said:

A relay is just a switch that you can control with electricity (either mechanically or electronically). Think of it as a switch that turns on/off with an electric current instead of your finger

sorry dany_boy, im gonna have to give it to hackentosher. thanks for the help guys it was really useful. 

peace

[Hackentosher]

1 minute ago, dany_boy said:

A relay is just a switch that you can control with electricity (either mechanically or electronically). Think of it as a switch that turns on/off with an electric current instead of your finger

ayyy, we said basically the same thing.

[JonaChan]

1 minute ago, Hackentosher said:

ayyy, we said basically the same thing.

you want me to give it to him? 

i picked you cause you were there the whole time

plus your explanation was a little more understandable

i guess i can count him best answer if ya want me to

[dany_boy]

1 minute ago, JonaChan said:

sorry dany_boy, im gonna have to give it to hackentosher. thanks for the help guys it was really useful. 

peace

Sorry for what? As long as you get the knowledge you needed then I'm good. Not here for points or stats.

Cheers!

[JonaChan]

Just now, dany_boy said:

Sorry for what? As long as you get the knowledge you needed then I'm good. Not here for points or stats.

Cheers!

hey, i can respect the fact that you do this for a passion instead of for points lol

cheers

[mariushm]

Yeah, the "use a bunch of mechanical relays" would work. There's 8 wires in the ethernet cable, so you'd need at least 4 mechanical relays, if you use the DPST /DPDT (double pole single/double throw kind) meaning each relay has 2x2 pins and can create connections between each set when it's energized.

Note though that unless you get latching relays (which keep the state once it's set), you'd constantly consume power keeping the relay turned on for a long period of time.

 

But really, it's almost (not almost, i'm sure it is) cheaper to just use the cheapest 5 port ethernet switch and plug the cable in the switch and then the cable going to various devices in another port of the switch. The switch would just receive packets from one cable and pass them to the other cable. Then when you want to break the connection, you just use a mosfet or transistor on the power cable going into the switch, to disconnect the switch. Switch turns off, the connection breaks and all the devices connected to the switch no longer have ethernet.

 

Such a simple cheap ethernet switch won't use much, maybe 5v at 100-300mA, let's say 3 watts. Could be even possible to power both the switch and the arduino board using the 5v adapter the ethernet switch comes with.

 

If you don't want the arduino to keep the circuit energized so that switch won't turn on, you can buy one latching relay, set the relay to disconnect the circuit and when you want the switch to get power you can just hit the relay again and make it connect the power to the switch.

 

Ex.

10$ for  5 port 100mbps switch : https://www.newegg.com/Product/Product.aspx?Item=N82E16833704026

12$ for 5 port 1gbps switch : https://www.newegg.com/Product/Product.aspx?Item=0XP-0020-00014

 

Going the relay route would cost you around 1$ per relay or about 1.5$ for each double relay so you're already about 5-8$ in cost. Circuit board, transistors to turn on or off relays, protection diodes for kickback from relays, prototyping board .. costs you more than 12$.

 

as for that question about tapping into video signal ... yes, it's very possible but you need microcontrollers or FPGAs running at very high frequencies and with enough memory to store one full frame, overlay what you want over the image, then send the edited image further.

It's much easier with older VGA since you have analogue to digital converters readily available to convert the images to digital and then you also have digital to analogue converters readily available to send the image to a monitor.

 

With HDMI and Displayport and DVI, these are digital connections where data is sent to the monitor as a very fast series of bits (billions per second) and sometimes this series of bits is encrypted using HDCP so you really need very fast processor in whatever you use to read this series of bits and convert it into the image and then overlay something over that then convert that back to a series of bits and encode those bits in the format monitors expect .. creating a digital signal is also quite a lot of work and usually again FPGA chips or specialized chips (like tiny video cards) are used... expensive and hard to program them to do what you want and often you can only get access to documentation if you agree to buy lots of them and if you sign NDAs (non-disclosure agreements)

 

[Tsuki]

they actually make programmable outlet timers.

you set a time, and it will automatically turn on or off at the set time.

 

we use them when we go on vacation for the lights so the house looks like somebody is actually home when we arent