Large Model Association Forum

hi all

i need clarification on a minor issue

i need to make up long servo extension lead 1m 2m and 3m leads

questions

what is the maximum length you can make up without degradation of power and signal on a 4.8 volt, 6v, and 12v with 6v Ubec, systems?

which is the best gauge 26awg, 22awg, or larger, for making a loom up?

do you need to add power signal booster over a certain length?

where is the best place get twisted servo wire from in 10m, 20m or 30m rolls at a reasonable cost?

constructive advice very welcome

thanks all

Richard, Google "The Components Shop", they sell heavy duty servo wire off the roll in Futaba and JR colours and at very reasonable prices. It comes twisted and is very supple, not like some of the harder, brittle feeling wire that you see. I'm putting it in the Sea Fury. Jonesey.

Hi Rich, +1 with what David has advised about "The Components Shop". At 4.8V I would not want to be making up servo extension leads anything longer than 1 metre out of the "normal" servo cable but I do know that it is done. I always prefer to use the heavy duty cables irrespective of the length as it is alleviating a "common" issue of power supplied to a servo. On 6v & above it is not such a problem as you again should ordinarily use a heavy duty cable.
I'm sure one of the very large model flyers will be along soon to advise what they use on their "larger" models!
Cary

thanks David and Cary i will look at the components shop, but i was looking to buy in bulk 50m rolls

richard armstrong wrote:thanks David and Cary i will look at the components shop, but i was looking to buy in bulk 50m rolls

Rich, send a message to Dave Johnson & ask him what cable he uses? He's pretty good at responding!
Cary

Hi Richard, I guess the kind of models my son makes will give some idea of cable to use.ie, almost full size.( see 86% Pitts Python on youtube). I do the electrics on the models and tend to make my own cables up from twin 42 strand speaker cable which will handle 10 or more amps adequately and is extra flexible, twisted with the signal wire which can be a lighter gauge. I twist the cables together in lengths of about 5 mtrs using an electric drill and 'blobbing' the wound cable with cyno every 5 or 6 inches to hold it together. This cable handles up to four very heavy duty servos simultaneously on 6 volts (fed from a bus bar, not through the receiver of course) at distances in excess of 3 mtrs. This may seem a bit extreem but the heavy duty modellers cable would produce too much of a voltage drop with the loading and lengths involved. You may not need to go so heavy duty but if you do I would suggest this method. ps. I use standard heavy duty three pin connectors, the type in white plastic bodies with pins and sockets which you solder the wires to and push into position in the holder, CPC sell them and the speaker cable. Use the steel tin plated pins/sockets, not gold plated because the gold can't handle high currents.

Dave Hayfield wrote:Hi Richard, I guess the kind of models my son makes will give some idea of cable to use.ie, almost full size.( see 86% Pitts Python on youtube). I do the electrics on the models and tend to make my own cables up from twin 42 strand speaker cable which will handle 10 or more amps adequately and is extra flexible, twisted with the signal wire which can be a lighter gauge. I twist the cables together in lengths of about 5 mtrs using an electric drill and 'blobbing' the wound cable with cyno every 5 or 6 inches to hold it together. This cable handles up to four very heavy duty servos simultaneously on 6 volts (fed from a bus bar, not through the receiver of course) at distances in excess of 3 mtrs. This may seem a bit extreem but the heavy duty modellers cable would produce too much of a voltage drop with the loading and lengths involved. You may not need to go so heavy duty but if you do I would suggest this method. ps. I use standard heavy duty three pin connectors, the type in white plastic bodies with pins and sockets which you solder the wires to and push into position in the holder, CPC sell them and the speaker cable. Use the steel tin plated pins/sockets, not gold plated because the gold can't handle high currents.

Thanks dave but i don;t intend to go that big but ideal set up super giant sized models over 1/2 size, the max size i intend to go is 1/3 scale,

later this year i will be taking possession of a 1/3 scale Cessna kit,

i was thing buying 20awg red white and black cable and twist my own?

Cary Bailey wrote:

richard armstrong wrote:thanks David and Cary i will look at the components shop, but i was looking to buy in bulk 50m rolls

Rich, send a message to Dave Johnson & ask him what cable he uses? He's pretty good at responding!
Cary

i will have a chat to him at rougham

Richard---I did same as you have done and took advice off here and bought a 50m roll of heavy duty wire of the net---I will check where it came from for when I see you next week----

Use a calculator like this one

http://www.calculator.net/voltage-drop-calculator.html

For example, 10ft of 22awg (heavy duty extension lead) at 6V drawing 2A will drop 0.65V, leaving 5.35V which will still work.

The signal is a considerably lower current, so over the same length will drop not a lot.

Rob Buckley wrote:Use a calculator like this one

http://www.calculator.net/voltage-drop-calculator.html

For example, 10ft of 22awg (heavy duty extension lead) at 6V drawing 2A will drop 0.65V, leaving 5.35V which will still work.

The signal is a considerably lower current, so over the same length will drop not a lot.

thanks rob that was helpful

Dave great let me know see u all at rougham!