Need to physically extend a USB cable.

[Guarino]

Hi all, I recently bought a security camera which comes with a non-detachable USB cable. This cable is too short for my needs, so I want to cut off the USB port, and solder some wires to extend the length, and connect the wires to a 5V power supply (like the ones used to power LED strips). Thing is: wires inside the cable that carry power will be easily recognisable if they are a different gauge than the ones deputed to carry data signal, but what if not? So my question is down to: can I use a multimeter to test what wires are deputed to carry power if they are all the same gauges? Remember the cable can't be connected to any power source, since one end is permanently attached to the camera, and the other end (with USB connector) is chopped off.

 

I have some soldering skills but have never touched a multimeter, so pls describe the process if possible.

 

I can't buy a USB cable extension because I need this cable to run into the same path of my house electric circuit and there is not enough space for USB connectors

[MrDrWho13]

Just go by the colours?

Id' be extra careful when stripping the wires since they'll likely be very thin strands.

[emosun]

the wires are colored so this shouldn't be an issue

also , buy like a 2 foot extension cable and chop the end off of that instead of the cameras cable. 

[mariushm]

The USB is designed to work with maximum 5 meters of cable, longer than that and there's too much loss on the wires and the wires are too thin and have too much resistance and therefore too much voltage drop on the wires for the usb controller and for the device to properly decode data packets.

 

If your distance is more than 3 meters, your best option is to buy an active extension cable which extends the cable to the maximum 5 meters, or to around 10-15 meters.

 

* 5 meters usb 3.0 : https://www.amazon.com/dp/B0179MXKU8/

* 10 meters usb 2.0 : https://www.amazon.com/BlueRigger-Female-Active-Extension-Repeater/dp/B005LJKEXS/

 

But again, these extension cables don't do anything special about the power delivery through the usb cable, so they'll be fine for data and for something small like a keyboard or mouse (less than 100mA) but they probably won't be good enough to deliver up to 500mA (for usb 2.0) or 950mA (usb 3.0) and keep the voltage within the aceptable limits (5v +/-5% or whatever the standard says)

 

Here's the math ... the best cables use probably AWG24 wires for power delivery, which means they have a resistance of 80 mOhm per meter, so with a 5m usb cable, you're looking at 10 meters between the power source and the device (because power has to go to device and back), so the overall resistance of the wire will be 80 x 10 = 800 mOhm or 0.80ohms.

You can calculate the voltage drop on the wires, using Ohm's law ... V = I x R  ( Voltage = Current x Resistance)

 

So for every 100mA (0.1A),  you'll have a voltage drop of V = 0.1 x 0.8 = 0.08 v minimum.

So, you have  4.92v @ 100mA , 4.8v @ 250mA , 4.6v @ 500mA , 4.2v @ 1A 

Look at your video camera power rating, if it's powered from the same usb cable. If it uses more than 250 mA and your cable will be longer than 5 meters, you will probably have to power it separately.

 

What I would do would be to:

 

buy one of the extension cables above

buy an equally long run of AWG18..AWG20 pair of insulated wires through which I'd deliver 12v to the camera

buy a small  usb car charger, the kind that powers from cigarette lighter, and open it up to take out the small dc-dc converter which produces 5v from 10v ..16v (dirty power from car battery and alternator)

buy a small metal (or plastic) project box, just enough to hold the thick connector of an active extension cable like the ones above , the tiny pcb pulled out from the car charger

(optionally) buy a meter or some small length of steel or plastic sleeving, just enough to hide the fact there's  2 cables coming out of the small project box and going into the wall

cables from camera go into the box , usb data wires go to a usb connector and into the extension cable, power cables go into the dc-dc converter to get 5v from the power cables which  bring 12v  - can't mess around with the voltage on the extension cable because it has amplifier chips on it and those run at 5v or 3.3v so they'd probably explode with 12v

Use a 12v wallwart adapter to send 12v to the dc-dc converter in the project box ... with 5-10 meters of cable you'd have maybe 10v or more which will be fine for the dc-dc converter to produce 5v for the camera

 

You could make the cables from the camera super small, just 5-10cm and basically the small box would look like the ferrite beads/nodules on display cables, or you can use some double sides adhesive tape to glue the box to the wall behind the camera like a wall socket (and run the cables in hole behind the box) 

 

* extension cable (amazon)

* 5v power supply from 12v  example 5v at 1A for 3$  ,  example 5v at 1.5A for 4.3$ ,  long list of supplies which can do 5v @ 1A or more : LINK

* cable 7$ for 7.5 meters of AWG22 pair of cables (for 12v to box) : LINK  or   10$ for 15m

* 12v wallwart  : LINK

* boxes  LINK

 

 

 

[Guarino]

1 hour ago, mariushm said:

The USB is designed to work with maximum 5 meters of cable, longer than that and there's too much loss on the wires and the wires are too thin and have too much resistance and therefore too much voltage drop on the wires for the usb controller and for the device to properly decode data packets.

 

If your distance is more than 3 meters, your best option is to buy an active extension cable which extends the cable to the maximum 5 meters, or to around 10-15 meters.

My only concern is power, since data will be managed through Wi-Fi. I have a bunch of AWG 10 and AWG 15 cables laying around, so I can run that from the power supply to the hole on the wall near the camera, and cut the camera cable of a length which is just right to reach the hole, so I should be able to use a longer wire, preserving much of the voltage, right?

 

Anyway I don't really know how much power the camera takes, the power brick has an output of 5V 1A, so I think the camera should be 0.5A or less. I don't have a USB tester to check the operating power consumption.

 

Assuming 0.5A running AWG15 at 10m distance (20m wires), I should just lose 0.1V, which should be well within spec, and the last 1m with AWG24, I should be a little over 4.8, again within spec, at the camera. This, if I did my math right.

[Unimportant]

1 hour ago, Guarino said:

My only concern is power, since data will be managed through Wi-Fi. I have a bunch of AWG 10 and AWG 15 cables laying around, so I can run that from the power supply to the hole on the wall near the camera, and cut the camera cable of a length which is just right to reach the hole, so I should be able to use a longer wire, preserving much of the voltage, right?

 

Anyway I don't really know how much power the camera takes, the power brick has an output of 5V 1A, so I think the camera should be 0.5A or less. I don't have a USB tester to check the operating power consumption.

 

Assuming 0.5A running AWG15 at 10m distance (20m wires), I should just lose 0.1V, which should be well within spec, and the last 1m with AWG24, I should be a little over 4.8, again within spec, at the camera. This, if I did my math right.

Another option is to just extend the mains power with a regular extension cord and have the power brick close to the camera. Electrically this makes the most sense.

[Guarino]

19 hours ago, Unimportant said:

Another option is to just extend the mains power with a regular extension cord and have the power brick close to the camera. Electrically this makes the most sense.

of course i'm not that stupid. This is an outdoor camera, and i can't install a bulky waterproof outdoor outlet cause i don't want to ruin my house aesthetics. My goal is to just "show" a wire, which will be painted the same colour of the house' outdoor wall, and leave all the electrical components safe from water and hidden in the house walls.

[Unimportant]

41 minutes ago, Guarino said:

of course i'm not that stupid. This is an outdoor camera, and i can't install a bulky waterproof outdoor outlet cause i don't want to ruin my house aesthetics. My goal is to just "show" a wire, which will be painted the same colour of the house' outdoor wall, and leave all the electrical components safe from water and hidden in the house walls.

I don't see why that makes any difference. I doubt your walls are several meters thick (?)

Mount the camera outside, feed the wire inside trough a hole in the wall, as you'd need to do in any case, but then inside, extend the mains power toward the camera site rather then extending the camera wire to the closest mains site.

 

You don't need to use thick bulky wire, current will be tiny at the mains voltage level. You can extend it hundreds of meters with hardly any loss in this case.  That's exactly the point. Only make sure the wire is rated for 240V/120V, depending on what the mains voltage is where you live.

 

That's what a professional electrician would do in such a case anyway.

[straight_stewie]

On 1/27/2018 at 6:39 AM, Guarino said:

I have some soldering skills but have never touched a multimeter, so pls describe the process if possible.

multimeters are shockingly simple. For this project you care more about resistance mode than anything else. Take the two leads, touch the wire at the end of each cable (that is presumably connected). If it reads infinity or error, they aren't connected. If it has a low reading, they are connected. If it has a valid reading, but is a little high, look at your soldering job.

Oh, and make sure that the cable isn't connected to power while you're doing this. If you don't, you will get faulty readings, or even damage the multimeter.

 

Quote

 and i can't install a bulky waterproof outdoor outlet cause i don't want to ruin my house aesthetics. My goal is to just "show" a wire, which will be painted the same colour of the house' outdoor wall, and leave all the electrical components safe from water and hidden in the house walls.

Step one is install the outlet, step two is install a bush. Azalea's work well in my area, check with your local extension office or gardening club for what works well in your area. 

Having an outlet outside is both less obtrusive and more useful. You want curb appeal? Great, but when they are viewing the house as potential buyers, they'll see an extension cord running down the wall and be spooked. Trust me, it's 20 times more ugly to have a wire running up your wall then it is to have a well placed outlet that's view is hidden from the street.