Checking voltage on LED power supply ?

Gdetrailer wrote:

JoeH wrote:
All great info and much appreciated. I have a Harbor Freight free analog meter out in the storage trailer. I'll see what that does just for fun .
I was also reading that hooking the 5050 LED strip lights to AC would work but reduce their life span. Recommendation was to get a 12v AC to 12v DC rectifier/converter.

Generally, running LEDs on AC is not a problem.

LEDs only "conduct" in the forward direction.

5050s require 3.0V per diode in the forward direction and are capable of handling up to 5V per diode reverse voltage.

SEE HERE FOR 5050 SPECS

Typically multiple LEDs are connected in "series" (pos of one connected to negative of the next one) same idea as a flashlight that takes multiple batteries.

Many "strip" light assemblies for 12V will connect 3-6 LEDs in series to run off of 12V depending on the diode forward voltage..

Which is why when you buy flexible and cutable strips they have a place marked for cutting.. cutting anywhere else and you break the series circuit..

Good example is pix below.


Click For Full-Size Image.

The issue I have with that setup there is no "current regulation". Slight variations in voltage can cause the LED current to swing past max values with only .1V change..

Better LED assemblies will use a current limiting resistor which will give a longer life.

Best LED assemblies will use a current regulator power supply which will give you max life and tolerate larger voltage swings.

If it makes you feel better, just s simple "12V" DC power supply is all you need.. Of course that power supply would bypass your current landscape transformer that may have timer and or dusk to dawn sensor just for your new added LED lights..

But I suspect leaving your new LEDs attached to the landscape supply will not do much harm if any to the LEDs life..