Step 1 : What do you mean


I'm in Australia but this may also apply elsewhere. Many sets of flashing fairy lights come with a little control box that has a push-button on it. You can select one of 8 different settings like: Combination, Twinkle, Slow-glow, Hard-on etc. The problem is they don't remember the setting from one night to the next so you have to push the button again every night to select the setting you like. If you have lots of sets of lights it becomes a real nuisance.

This how-to tells you how to modify the controllers so they remember the setting from one night to the next. It basically involves cutting open the case and installing a large value capacitor to keep up power to the controller chip (often marked LS-11).

Step 2 : Safety

Most sets of flashing fairy lights like that in Australia are powered from a 35v or 24v transformer. There are no safety concerns with those ones.

Some sets (eg. some rope lights) run direct from 240v. In the USA I presume most sets run direct from 110v. BE VERY CAREFUL with those ones!!! There is high voltage at ALL POINTS within the controller, including in the "low voltage" (5v) area. It is not 5v with respect to ground but is 5v with respect to 240v or 110v. eg. one side of the IC is 240v and the other side is 235v. SO BE CAREFUL!

- Unplug from power point before opening case.
- Close and re-seal the case before testing.

Step 3 : What do I need

- Hacksaw
- Soldering iron and solder
- Duct tape
- Small piece of connecting wire
- 1000uf, 10v capacitor or 1F, 5V memory backup capacitor
- 5.6K 1/4W resistor (for 1F cap)
- 1N4004 diode (maybe)

Step 4 : Terminology

In relation to the controller case:
"Front" - the big side with the button
"Back" - the big side without the button
"Bottom" - the short side where the wires enter
"Top" - the short side where the wires don't enter
"Sides" - the long sides between the front and back

Step 5 : Opening the case


The case is normally glued together so it has to be cut open with a hacksaw.
- DISCONNECT FROM POWER SOURCE!!!
- Secure the case gently in a vice
- Cut all around the case (sides, top and bottom), 5mm (3/16") from the front. (See white line on photo). Be careful not to cut too deep.
- Cut across the back parallel to the top and bottom, at the bottom of the square with the writing on it. ie. about a third of the way up from the bottom. (See next photo)
- Remove the front (see photo further down)
- Continue the cut on the back so it goes around and across the sides as well.
- Remove the top half of the back. You now have three pieces, the front with button, the bottom rear third with wires and circuit board attached, and the top two thirds of the back. Use a screw driver to gently pry apart the pieces if the saw did not cut right through the case.