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See ‘N Say Audio Files – Convert Speaker Output to Microphone Input

 ·  ☕ 2 min read  ·  ✍️ Kevin Neubauer

See ‘N Say Toy

I picked up a cheap See ‘N Say toy at a thrift store a while back. I decided I would so something fun with it, which will hopefully make it into its own post after finishing it. At first I wondered about doing something with the audio clips that were stored on the toy. Of course, after opening it up there’s a big blob of black epoxy over the microcontroller. This makes reverse engineering it to dump the stored audio bits too much of a challenge.

See ‘N Say Circuit Board

Rather than give up, I decided I would put together a solution that’s good enough. I used a simple voltage divider with a potentiometer on one side to make adjustments to the audio output signal. I hooked the output of the speakers up to one end of the voltage divider and on the other end is a TRRS 3.5mm headphone jack breakout. The + from the speaker output is hooked up to the microphone ring on the jack and the – is hooked up to the ground.

For people wanting to follow along at home, there is no schematic for all situations. Each toy could have a different level of amplification or voltage output. Likewise each microphone input could have different expectations for voltage input level. I ended up using a 512K potentiometer and a 10K resistor. It’s very important to measure the voltage output to the speakers to determine how much resistance is needed to drop the voltage to a level suitable for a microphone input. You could end up damaging sensitive microphone electronics if you fed too high of a voltage into it.

I adjusted the potentiometer to adjust the signal to well below 1 volt peak to peak (1 volt is line level input) and measured it with my oscilloscope prior to plugging it into a computer. Once all hooked up, I started audio recordings on the computer and played the individual sounds from the toy by pressing each button. It’s a bit of a hack solution but was good enough to get quality audio out of the toy.

See ‘N Say Circuit Board

I’m putting these audio files up here in the hopes that someone will find them fun and do something with them.

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Kevin Neubauer
Kevin Neubauer
Security Engineer (Hacker)