Introduction: Insulated Audio Cable for Cochlear Nucleus CP800

This thing is intended to provide safe connection of audio output from phone or tablet to Cochlear Implant Processor Nucleus CP800.

You may buy factory-made cable-adapter at price of roughly $120, or you may create it by yourself at cost of about $12 (and get it as long as you need).

If you're not wearing cochlear implant, and reading this just because of curiosity, feel free to google on cochlear implants. Chances, you will be surprised.

First of all, you're doing it at your own risk, using hand-made adapter for such expensive equipment as cochlear implant processor.

So, be careful and get this project seriously. Also, it's better if you had some engineering experience.

Step 1: Instruments You Will Need

1) Glue gun

2) Side-cutter

3) Solderer

4) File

5) Drill + bit (choose bit diameter as thick as your audio cable)

6) Hack-saw

7) Knife

8) Multimeter

Step 2: BOM (bill of Materials)

1) INSULATED audio transformer with 1:1 ratio. BOURNS SM-LP-5001. Datasheet attached.

2) Child lipstick

3) Good audio cable with audio 3.5mm one male connector and one female connector.

Step 3: Disassemble the Lipstick and Cut It With Hacksaw

First, disassemble the lipstick in half and save both parts.

Then try to figure out how much space you need for audio transformer in the case of your lipstick.

Actually, you may use whole body of lipstick case, however, if you wish to have some more compact design - cut the cup on length of about 17mm.

Then fine it's edge with a file a little.

When finished with cap, pop out part of the bottom part of lipstick case, using knife. Well, you may have a lipstick of another design. Mine was not monolith on the bottom, so you may try too.

Make sure that there is enough place for audio transformer.

Step 4: Drill Holes in the Plastic Cups

This step is pretty simple.

Pick a bit with diameter near as thick as your audio cable and make one hole in each cap.

Step 5: Cut Audio Cable in Half

Cut audio cable in half and strip it's ends.

Then put each cable through the holes as shown on the picture.

Step 6: Solder Cable's Wires to the Transformer

Here is schematic of the BOURNS insulated SM-LP-5001 series transformer.

Note: We are going to connect only one audio channel, but you may create stereo-adapter, just use two transformers and all three wires in the cable in that case.

First, check your transformer against shortcut between windings. Apply multimeter connectors between transformer's pins 1 and 6 (see picture). There is should NOT be a shortcut.


You may use some another audio INSULATED transformer. Anyway, you need to make sure it has really good insulation between windings. For example, SM-LP-5001 may withstand up to 2000V. Ratio 1:1 is also essential.

So, we will use two wires from the cable - one from the Ground contact, and another one from left or right channel.

Check it using multimeter.

Solder one cable's Ground and left-channel wire to the transformer's pins 1 and 3. And from another cable - to pins 4 and 6.

Again, use multimeter in Ohmmeter mode to check that there is no connection between one cable and another.

Step 7: Assemble the Body

Put transformer into one cap and secure it using hot glue - little by little.

Then, secure another cable and put second cap on. Secure it with hot glue too.

Step 8: Test for (NO) Short Sircuit Between Input and Output

Again, use multimeter in Ohmmeter mode to check that there is no connection between one cable and another.

I believe, that those of you, who will build this project, have some engineering experience, so there is no need to excessive pictures.

Feel free to contact me anyway.

Step 9: