voltage drop 12VDC 1.5 Amps on CAT 5

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can one of the gentlemen among you advise me on this please.

 

If i have a 50 meter CAT 5 / ( RJ45 ) cable run to a camera (400 mA) and want to also run an IR array (1000 mA)

 

Is that too much current to put through the 50 meters of CAT5 cable and run both camera and IR ?

 

Is it likely to cause any interference in video signal ?

 

 

i have BNC/RJ45 baluns to use marked 100 // 75 Ohm

 

 

second question , if i need to run RJ59 coax for the first 4 meters and last 2 meters to the cable , will that cause much deterioration of signal ?

 

I would take CAT5 all the way but a junction box for the balun will attract attention to the discreet camera if i do that.

 

 

thanks people.

[Soundy 1]

If i have a 50 meter CAT 5 / ( RJ45 ) cable run to a camera (400 mA) and want to also run an IR array (1000 mA)

 

Is that too much current to put through the 50 meters of CAT5 cable and run both camera and IR ?

According to this calculator, using all three extra pairs, you should see about 1.4V loss; if the power supply voltage is adjustable up to 13.5V, you should be fine.

 

 

Is it likely to cause any interference in video signal ?

No.

 

second question , if i need to run RJ59 coax for the first 4 meters and last 2 meters to the cable , will that cause much deterioration of signal ?

No.

[survtech 0]

If the IR-LEDs operate all of the time, 13.4V setting at the supply and 3 pairs for power (+ 1 pair for video) will be fine. However, if the IR is switched on/off by a sensor, the camera's voltage will vary quite a bit. Assuming the total draw with IR on is 1,400mA and with IR off is 400mA:

 

IR OFF (50m/400mA) = 1.6V loss (1 pair), 0.8V loss (2 pair), 0.4V loss (3 pair)

IR ON (50m/1400mA) = 5.8V loss (1 pair), 2.9V loss (2 pair), 1.4V loss (3 pair)

 

Even running 3 pairs, you will have a difference of 1 volt (8.3%) at the camera between IR ON and IR OFF. If you set the supply voltage at 13.4 volts with IR on (to get 12.0V at the camera), the camera will see at least 13 volts with IR off. On some cameras, that could cause:

 

 

You might try setting the voltage with 3 pairs and switched IR so that it is about 0.5V volt less with LEDs on (12.9V at the supply). That would make the voltage at the camera vary between 11.5V and 12.5V. Well-tolerated by almost every camera.

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thankyou to both for above replies

 

first class

 

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I have decided to go with 24 VAC up the CAT 5 and then put a reducer down to 12 VDC at the end and run Fig 8 cable for the last 2 metres

 

which is the better wiring method to use the 3 pairs for power out of the two options in the attached sketch so i reduce any signal distortion ?

 

thankyou folks.

 

[Soundy 1]

That diagram is incorrect for T568A. T568A is the same layout as T568B, except the orange and green pairs are reveresed:

 

 

That aside, there should be no worry about interference regardless of which pairs you use for video and power.

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That diagram is incorrect for T568A. T568A is the same layout as T568B, except the orange and green pairs are reveresed:

 

 

That aside, there should be no worry about interference regardless of which pairs you use for video and power.

 

 

what i meant was , out of the 3 pairs available for power , do i connect in parallel one wire out of each pair so for example i connect orange brown and green wires together as one 24 VAC connection , and the Orange/white , brown/white and green/white wires tied together as the other , as i have drawn in the bottom sketch of the two above ?

 

my baluns have pin 7 and 8 connected to the power terminals on the outside of the balun , but i am using 3 pairs for power to reduce voltage drop so i have to put jumpers to use all 3 pairs for power.

 

you probably have an easier way to do that ?

 

 

thankyou

[Soundy 1]

One type of video+power baluns I'm using put the video on wires 1+2 (which with T568B means orange), then one side of power on 3/4/5 (green/white wire, and blue pair) and the other side on 6/7/8 (green wire, and brown pair). I know other people who do the stripes for one side and solids for the other, if they're wiring manually.

 

One pair for video... the others, it really shouldn't matter how you do it.

[jack in oz 0]

I have decided to go with 24 VAC up the CAT 5 and then put a reducer down to 12 VDC at the end and run Fig 8 cable for the last 2 metres

 

Hi there,

How are you going to do the voltage conversion? Is that 24VAC for the camera and 12VDC for the LEDs? Sounds like a good solution.

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I have decided to go with 24 VAC up the CAT 5 and then put a reducer down to 12 VDC at the end and run Fig 8 cable for the last 2 metres

 

Hi there,

How are you going to do the voltage conversion? Is that 24VAC for the camera and 12VDC for the LEDs? Sounds like a good solution.

 

the camera ( 300 mA ) and IR panel ( 900 mA ) are both 12 VDC

 

i didnt want to put voltage spikes into the camera every time the IR panel switched off and on , thats why i have run 24 VAC up the CAT 5 and put the 12 volt PS close to the camera , i might even put a capacitor across the DC supply to the camera as well to smooth out the supply.

 

i could have got a camera with built in IR LED but i find that IR attracts flying insects , which attracts spiders to build spider webs in front of the camera

 

by putting a separate IR panel a couple of meters to one side away from the camera it avoids the insect issue and gives better facial recognition due to the side lighting

 

It also gives better night vision when its raining , decreases frequency of motion activation by rain drops or insects and the HDD is not full of pretty pictures of sparkly raindrops

 

on the topic of the capacitor across the power supply , anyone got an opinion on what value electrolytic cap to put across that ?

 

16 volt or so ? , 0.01 uF ?

 

[jack in oz 0]

on the topic of the capacitor across the power supply , anyone got an opinion on what value electrolytic cap to put across that ?

 

16 volt or so ? , 0.01 uF ?

 

 

I'd say it depends on the type of PS you are using. If it's a switchmode PS I wouldn't be adding any capacitance to the output. If it's includes a linear regulator like an LM338 it should already have a capacitor at the output. In fact, any properly designed PS should not need "tweaking".

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thanks Jack.