Femisapien Wrist LED Hack: Turn Them Any Color You Like

I found Femisapien's red wrist lights didn't quite suit her, so I decided to replace the LEDs with something a little more fashionable.  I decided on pink LEDs, as they are still quite unique, as well as being feminine. This tutorial will take you though the process of replacing the LEDs, including something on LED selection and purchase tips. As a standard disclaimer, I'll say you modify your robot at your own risk of course, and you should not attempt anything you do not think you can handle. I think most will find replacing Femisapien’s wrist LEDs a relatively easy job though, provided you have a soldering iron. Hopefully this step-by-step helps others thinking of making the LED swap. This mod is also relatively simple, and if you ever don't like the result then you should be able to swap them back easily enough.

Step 1: Purchase LED's for Femisapien's Wrists

First you need to get your LEDs. You don't have to go with pink either, you can get many different colors incredibly cheaply on eBay. What you want is high brightness 3mm LEDs. There are some things to note with LEDs, including that not all LEDs are created equal, especially pink ones, as I've found!
LED's fresh from Hong Kong, via eBay.

WowWee Femisapien LED Wrist Light Mod & Hack
LEDs fresh from the packet. Ultra-bright LEDs almost always have a clear lens, but these ones here will light up pink. These ones also came with resistors, but you won't need them, so don't worry if yours don't.

Femisapien's ready for her operation, showing us the seven screws in her wrist and arm. Three different screw sizes are used, so be careful not to mix them up.

Step 2: Disassemble Femisapien's Wrist

First, undo all four screws on the arm, and all three screws on her wrist. Note that there are three separate screw sizes. The screws used in the wrist are slightly bigger than the larger screws used in her arm. Once you have all the screws out, gently spread her wrist apart. I found it helped to slightly squash the shell sideways, squeezing on the seams to pop the two halves apart. This should spread them enough for you to get a fingernail in to complete the job. You then want to take each half out of the arm separately. You need to do it this way because there is a rod that extends down into her wrist from her arm. The end of this rod has a plastic wheel on it that is trapped in the wrist until you spread the halves.


Step 3: Expose the LED

Once inside, you’ll immediately see what you are after. A small (3mm) clear LED is inserted into the ear-bud shaped wrist light. It should fall loose as soon as you have the wrist apart. Remove the ear-bud light-pipe/lens thing first, so you can see the LED. There is black heatshrink insulation on the two leads coming from the LED. I found you can gently slide these down, exposing the leads and solder joints. Move the heatshrink tubing as far along as possible, as any heat you apply with your soldering iron will only cause them to become tighter. The insulation on the two wires connected to the LED are joined, and so I just separated them a bit more, to give me room to move the heatshrink down.
A detailed image of the inside of Femisapien's wrist.

WowWee Femisapien LED Wrist Light Mod & Hack
Femisapien's wrist opened up. The LED and light-pipe/lens has been moved out to more clearly see it. You may also note A) the LED, B) the heatshrink, C) the light-pipe and lens, D) the location the lens came from, E) the clutch plate, F) Femisapien's wrists interlock with her arms, so they must be split to be removed.

The light-pipe/lens removed to show the LED underneath, and the heatshrink slid down on one side, exposing the soldered lead. I know, my soldering isn't perfect, but you'll notice how I used only just enough solder to join them well, so the heatshrink could be slid back up.

Step 4: Replace the LED

Now just heat up each solder joint with your soldering iron and remove the LED. Take your replacement LED and cut the leads coming from it (which will be quite long) the same length as the LED you removed. It is best to then tin the leads. This means you should just heat them up quickly with the soldering iron and stick a little fresh solder on them where you want to attach the wires. The little bit of solder you add will make it easier to stick them to the wires.

Now, just stick them to the wires again. Don’t keep the heat any longer than necessary on the LEDs. Heat kills semiconductors, and it’ll travel along the wires and melt the insulation, and tighten the heatshrink too. The LED must also be connected in the correct orientation. The black stripe on the wires indicates the negative lead. Typically, the negative side of an LED is the lead with the flattened rim section of encapsulation (the LED lens and body) next to it, which is the side with the reflector inside the LED, and the shorter lead (before you trimmed them). The LEDs in my Femisapien were more unusual, in that the reflector side was the positive lead.


Step 5: Reassembly

Remember you want to slide the heatshrink tubing back up, so you want to join them as neatly as they originally were. Don’t put a big glob of solder on there, use only just enough solder to make the joint. Once you have the LED neatly soldered back on, just slide the heatshrink back up to insulate the leads again. Now its best to switch her on briefly, to check your LED lights and looks a good as you hoped. Do the same on the other side and you’re done! Well almost, you just have to screw her back together. Note that a small square of plastic with a spring on it tends to fall out when you first open the wrist up. That is the clutch, which prevents rough treatment from breaking poor little Femisapien’s wrists. There is a small square box where the clutch spring sits. See location E in the wrist image above.
Femisapien proud off her pink wrist lights!

WowWee Femisapien LED Wrist Light Mod & Hack
Femisapien proud of her pink wrist lights!

Here she is strutting her stuff, showing off her new lights.

Now you have a custom Femisapien! The LEDs you get will tend to be appreciably brighter than the ones you replaced too. They won’t take any more power though, in fact they will almost certainly take even less then the original ones. LEDs you buy separately just tend to be more efficient, and more focused in their light output, than the LEDs used in manufacturing.

I hope others get inspired to modify their Femisapien. She is a surprisingly engaging robot, from her fluid movement and walking, to her graceful shape!


Chris 22's picture

Very nice! Good work!

jstec's picture

Chris 22 said: Very nice! Good work!

Good work

bastelmeister's picture

Very nice idea,
but maybey its possible to replace the original leds with colorshifting leds !!!
i ame not shure if this will work on the Femisapien but i know the do exist.

i am gonna check it out soon.

bastelmeister's picture

Well, i found 5mm (RGB)FASTcolorshifting leds.
5mm is not easy to instal but the efect is absolutly illuminating!

I tryed 3mm fast colorshifting leds but, they dont seem to bring that much light.
And also the 3mm slow version but there not shifting fast enough so the effect doest show a all.

I will try to post a video of this mod.

bastelmeister's picture

 Well, here it is: fast colorshifting leds on my femi

Note: its not easy to fit 5mm leds into the tube/lens of the wrist but the effect is most  satisfying!!!



Elliotrobots's picture


bastelmeister's picture