Joule Thief

[crowclaw]

  I was very interested, as I did not think to look on the back for it.

I can see at least five other semi conductor devices on your circuit board, look at the small three legged ones.
Some of the latest solar powered garden stick lights also have even less! using encapsulated devices which appear as circular black epoxy blobs! Can provide various control functions from flashing effects  to multi colour modes.   

[WilbyInebriated]

using encapsulated devices which appear as circular black epoxy blobs!

that's what i was talking about. thanks for the better description! they are usually about the diameter of a dime and maybe a little taller than a dime. i see those a lot now on garden lights, etc.

for what it's worth, here is what one looks like...

[NickZ]

  That got me thinking so I took a picture of my motion lights pcb that use the solar panel I had shown earlier, and lights 5 leds. That circuit uses 5 AA batteries. Here is what that pcb looks  like, there is nothing on the back of this one, no blobs, or components.
Is that a 555 circuit that these are using??? I looked at it, but it does not say anything like 555 or similar.  It is mounted on a removeable type of socket.  If so, maybe it can be used elsewhere...

[WilbyInebriated]

  That got me thinking so I took a picture of my motion lights pcb that use the solar panel I had shown earlier, and lights 5 leds. That circuit uses 5 AA batteries. Here is what that pcb looks  like, there is nothing on the back of this one, no blobs, or components.
Is that a 555 circuit that these are using??? I looked at it, but it does not say anything like 555 or similar.  It is mounted on a removeable type of socket.  If so, maybe it can be used elsewhere...

my magic 8 ball says 'probability is good'... looking at the visible traces and the positions on the resistors i would say yes, it's a 555.
is it chinese? they like to copy IC's and leave them blank.

[NickZ]

  Even with a magnifier I can't read the print on it well enough to copy it, but it is not written in Chinese, nor does it say 555 anywhere.  I like the use of the socket that it plugs into,  it's easy to use on some other circuit, as I have several of these, and don't need them all.
  Sometimes it's just easier to use these types of ready made boards, instead of taking hours, or days to make or design the same or something similar oneself.
Even Dr. Stiffler had mentioned that China made a "knock off"  of one of his SEC circuits.