Power cords to props

[ron5526]

In an effort to speed up assembly (on site) of my controller to my props (5 controlled) I was thinking of using one of those 3.5mm audio cables (mono) with a plug at each end.  The kind you can pick up at one of the electronic supply houses for about a $1.50.  This would allow me to plug and play.  My concern is on how much juice they can handle.  My current best guess on my draw is 12vdc @100mA for a 12ft run. What this will basically be doing is connecting my Prop-1 to a relay located in each pop-up.  I may need to bump up the mA depending on my relay selection.  Any thoughts.  Oh...I have no clue as to AWG of those type cords.

[JonnyMac]

Audio cables like that don't have to carry much current so they are typically very small gauge -- I wouldn't use them to carry power.  And remember, you have to account for the power of the controller plus its maximum possible load.  The Prop-1 load is small, only about 30 mA, it's what you attach to it (solenoids, relays, etc.) that will start to add up.

Since you're constructing anyway, why not buy some 2.1 barrel connectors and zip wire from a supplier and build cables that you know will work?  Soldering a connector is not a big challenge and in the end you won't be troubleshooting brownout problems caused by insufficient power cables.

[ron5526]

I think making my own is the answer.  Found a cool link in helping with wire size/run/load:

http://www.video-insight.com/Support/Tools/Wire-Length-Calculator.aspx

-Ron

[JonnyMac]

It's too bad that doesn't give you a specific answer -- what is a "considerable drop in voltage"? 

[menehune]

Seems to be a calculator geared towards CCTV and security cameras.

You could try this calculator:
http://www.currentsolutions.com/knowledge/vdrop.htm

I wouldn't go over 5% voltage drop myself. 3% or less is ideal.

[ron5526]

Nice site.  Please forgive my ignorance but what does "in both directions" mean?  Would that mean on a 10' cord 20' would be entered?    source>>>>load>>>>>source

[JonnyMac]

I took it to mean there and back, so a 10' piece of zip wire would be 20' long.

[menehune]

I believe that is correct since each length of conductor adds resistance to the circuit.

[CoffinBound]

Mind if I ask what is zip wire?

[JonnyMac]

Zip wire is often called lamp wire; it has two conductors that can be separated.  You can get lamp wire at any well-stocked hardware store.

[barry]

I use 1/8" audio cables for power to my strobing LEDs.  These consist of boxes of 30LEDs each hooked up to a strobing controller.  I chain these together using the audio cables with no trouble at all until I hit the 8-10 mark (48-60 feet) where I start seeing reduced performance.

Barry