Build a Ski Helmet Walkie-talkie ("ACS")

If you've been in a ski/snowboard shop lately you might have seen the K2 "ACS" system for their helmets, which integrates a headphone on one ear for stereo listening, and a headphone on the other ear with a boom mic for talking to your buddies over your walkie-talkies. You press on your earflap to talk and release to listen.

This looked like great fun and better than the usual hollering across the slopes and digging out our walkie-talkies when we lost each other. It also looked like too much money for 2 earflaps and a headset, when I had the materials at home to build it in half an hour.

Here, I make a busted Xbox headset and my ordinary K2 helmet into a K2 ACS helmet!

Step 1: Modify Headset to Fit Under Your Earflap

With the broken Xbox headset, this was easy as it was already broken off of the part that holds it on your head. I just cut off the broken part and filed it smooth.

Remember, you want this to be comfortable. You are wearing it all day to ride!

Step 2: Reverse Earpiece and Microphone Connections, Add Talk Switch Connection

Most walkie-talkies use the opposite "polarity" on their connector to other headsets. So converting any phone/xbox/cell headset to walkie-talkies, usually requires popping it open and swapping the mic and headset wires.

Test it first! You may not have to swap the wires if you have weird walkie-talkies or a funky headset.

Use an ohmmeter to find the mic, earphone, and common wires. Leave the common wire alone.

Pics show before and after. Note the white and red wires have been swapped.

OOPS, I FORGOT A PIC!
The simple swap is enough for voice-activated use, but on the mountain, the wind noise is too strong, and you need to use push-to-talk.

The pic I forgot to show... was of me adding the wires for the push-to-talk switch.

You want to put a hole in the headset (there's already one there on the xbox headset) and feed in 2 wires for the switch. Remember to tie a knot for strain relief, or they could rip right out and destroy all your work.

Now, don't connect the microphone to the pad where you were going to swap it to. Instead, connect it to one of the wires going out of the headset. Connect the other wire to the pad. You have put the switch wires in series with the microphone.

Step 3: Two-cent Poor Man's Switch.

I know I'll get booos for this one. But I used the 2-penny switch for a reason, and not just because it only costs 2 cents.

It's hard to find a switch as thin and with as little action as the 2-penny switch, which is perfect to slip between the headset and the earflap. It has a very large area which responds to a very small force, meaning you can slap at your earflap with your glove and it will come on. It also means there are no external parts to get snow in or look ugly.

If you find a thin switch that you can activate with gloves on then by all means, use that instead. Or mount another switch on the outside if you find a nice looking one.

Anyways, image 1 shows preheating the penny. It's damn hard to solder to a penny, so use a big iron and try to balance the penny somewhere it won't conduct all the heat away. Once solder starts to stick to the penny, you can solder the wire to it. Do this twice, once for each side.

Now it should look like image 2. Let it cool, and then build a thin spacer on half of one of the pennies with tape. Can you see the tape in the pic? Build it thick enough that it will not touch unless you were to press on it.

Then wrap the whole thing up in tape like image 3. Note the gap between the pennies. Test it well with your walkie-talkie. Most important - it must not get stuck on! It should require a light press, but not too light.

Step 4: Putting It All Together

Cut a small hole in your earflap and push the microphone through so it will go in front of your face. It should be a very tight fit.

Position the switch with tape or something and give it some tests with your walkie-talkie. It should switch to transmit easily and reliably when pushing your earflap with a glove on, but not come on when you tilt your head. You may have to adjust your penny switch spacer, too.

When you find a good spot, fix it there with your favorite adhesive. Don't use one too strong, in case you find that nice switch you were thinking of to replace the pennies.