What are "blobs at ends of strings?

[brucet9 10]

I have strings of LED lights from Creative Displays.  There is a cylindrical "blob" just after the male plug and another just before the female plug on the 50-light strings.   70-light and 100-light strings have the same front and back "blobs" and one in the middle as well.  

I know that LED strings have a resister somewhere in the circuit to keep from overloading the LEDs, but that would require only one such "blob" for 50-light strings and maybe two for the two halves of longer strings.  Since there are two wires entering at the plug side of the end "blobs" and three wires from the other side, it occurs to me that they may also be junction boxes.  Maybe the center one is just a junction box for connecting the last LED for each of the two halves of the string to the neutral wire?

Can anyone "enlighten" me as to what these mystery cylinders have inside them?

[MrMatt 26]

Pretty sure they are rectifiers, leds don't work on AC Power directly the rectifiers restrict the voltage to only flow one way through the LEDs instead of alternating that switches directions at 60 Hz

[hotrod1965 44]

correct. Rectifiers to take your lights from 60hz to 120hz, which makes them brighter and flicker twice as fast you can't notice the flicker as much.

[qberg 158]

18 hours ago, MrMatt said:

leds don't work on AC Power

You are half correct   LEDs only work on half the AC wave if they are not "full wave" or "non flicker".  The blobs are resistors for half-wave leds (cheap walmart LEDs) or a couple diodes to make a rectifier ( full wave or non flicker LEDs) which changes the AC to a DC current.  Check out the planet christmas magazines as a couple of them dissect them and show how they work.

In your pics it looks like 3 wires between the blobs so i am going to say they are rectifiers. A resistor would be on a single wire in series with the LEDs and wired just like a strand of incans.