Quote:
Originally Posted by TeddyDiver
Not just voltage but regulated current.
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LED’s require a
current supply instead of a voltage supply. This is accomplished by calculating the value of a series resistor. This resistor then limits the current to the correct value but only at a specific voltage.
In other words: the requirement for a specific current supply is converted into a requirement for a specific voltage supply by this series resistor.
A LED strip is actually a flexible circuit board. It often has LED’s connected in series of three or six and can have resistors but also active components like transistors or even complex chips for addressing individual LED’s etc.
I have LED light bulbs that specify something like 9-30V
power supply. Those have a
regulator. This is the type that can interfere with
radio reception.
LED lights used for
navigation lights, even when specified for 12V only, still have a
regulator because it is expected to have very long circuit
wiring with voltage losses while
regulations require a minimum brightness. Hopefully these have internal shielding and filtering to suppress EM
noise to prevent
interference.
I have also seen LED’s in the familiar (Carling) toggle switches like almost every
boat has for
bilge pumps that state 12/24V. These have a resistor that is good for 30V but also a high efficiency LED so that output is still enough with 12V.
So you just don’t know what you get. On LED strips you can use a magnifier or microscope to examine components. If you have individual LED’s that fail on a LED strip then it is the LED itself that has failed. If it is a section of three LED’s or more, it’s probably another component. Either case is a sign of bad quality.