I recently purchased five LED strips online (these specifically: http://www.ebay.com/itm/331059064977) to hang up along the outline of my room. Each strip is 5m (16.4 ft.) long, requires 12 V DC to power, and dissipates 0.08 W/LED.
Each strip dissipates 48 W, meaning that at the recommended 12 V DC, there would be a current of 4 A.
I planned on soldering the five of them together in series so that I could have one long chain of LEDs that will only require one power source. However, I am slightly confused regarding what adapter I should purchase that will power the chain.
Each strip seems to come with two cables attached to both sides (power and ground); I'm a little confused regarding this, because I know that LEDs should be forward biased, so why would both sides require power and ground?
Also, because I will have five strips, should I be passing 60 V DC through the entire thing if it's recommended to only pass 12 V DC for each strip? I just want to make sure that I don't blow anything up accidentally by exceeding the maximum rated amperage (I probably wouldn't want to go over 4 A if possible).
Best Answer
If you hook them up end to end, you need just 12V, but at 5 times the current.
The strips actually have a circuit something like this (imagine the vertical resistor-led combinations between 12V and GND are repeated, going off for 5m):
simulate this circuit – Schematic created using CircuitLab
It may actually have multiple LEDs per vertical section (to avoid needing a high power resistor), but the principle is the same.
So, hooking them end-to-end is actually hooking them up in parallel. This arrangement is also how you can cut these strips without breaking them: You're just removing parallel LEDs from the chain.
So, just get a supply that supplies 12V at 20A.
Alternately, if you don't want to hook them up end to end and instead want to hook them up in "parallel", you are actually hooking them up in series and would require a 60V, 4A power supply.