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Hacking a T388 Walkie Talkie

I'm doing it! Finally working on the walkie talkie mobile. I took one apart, and it's such a simple mechanism!

The model is a T388, and it looks like these are just mass manufactured and rebranded for different companies. I found a manual for them (link here).

The walkie talkie has these gold medallion pads that interface with what I thought were rubber buttons. I thought they were capacitive, but they didn't activate on human touch. How could these dinky little rubber buttons be activating the walkie talkie?

A bit of googling later, and I learned that they are carbon tactile keys!!! (link here)

I confirmed this by pressing one of my music wires (made of carbon steel) against the pads, and alas, they activated!

From my research, I learned that what I thought were rubber buttons actually have carbon impregnated silicone pads that are fused to the button body. Fascinating!

So now I have to figure out how to activate the talk function without using a mechanical button...

There are some pads on the back, including 'talk' and 'ground' and I tried to activate the talk by sending power to it: 3.3V, then 5V, and then 6V, and it didn't work.

Upon closer look at the pads, I realized that the carbon pads are actually connecting two electrical traces. The pads are 2 interwoven traces, and the carbon pads are bigger than the spacing, so the circuit is closed when the carbon pad meets the electrical pad. When I poke either trace with the carbon rods, the action doesn't activate. When I touch both traces with a carbon rod, it activates.

So! My plan is to make an embodied switch, such that to activate the talk button, a person has to stand on top of a soap box. I can extend the logic of the separated traces into the top face of the soap box where people will stand. Brilliant! And easy!

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