I am very green when it comes to this subject and wondered if anyone could help.
Thought of using the cable for a small project who's spec is shown below and wondered if it is suitable.
I'm using either a 24v or 12v power supply and the current draw will be 500Ma max.
The cable is ideal for use in alarm installations or where low voltages are used.
Resistance 98.07Ohms/Km
PVC wall Thickness 0.50mm
Current Rating : 1 Amp
Max Voltage : 50V rms
CSA 0.22mm
Wire construction 7/0.18mm
Outer Diameter 3.5mm
The length of cable would be about 8 meters
The voyage requirements would be in the form of 4 LEDs with a forward
Voltage requirement of 3.2v per led connected as 4 strings of 4 LEDs
You know the resistance of the cable is 0.78x2 = 1.56 Ohms. (The wire goes there and back so it's 16 meters). You know the current requirement (500mA). Using Ohms law you can work out the voltage drop along the wire.
Your power supply needs to supply 12.8V for the LEDs (4x3.2) plus whatever the voltage drop along the wire is.
If you use a constant-current LED driver (which seems the right thing to do here) then it will happily take up any extra
voltage due to ohmic losses. Just make sure it can handle 5 LEDs in series (an extra one should allow for any cable losses).
LED forward voltage varies with temperature and trying to power them with a constant voltage can lead to thermal
runaway - so constant current or a current-limiting series resistor are needed.
If your cable had rather more resistance it might have been able to function as the current-limit resistor!