Walkie Talkie

Talk the Walk: Building Your Own Walkie Talkie

Lin Gan, Cheng-Kai Chen

Overview:

This project uses RF circuit to build a walkie talkie that is protable and afforadable.

Description:

Our RF walkie talkie circuit can be divided into five parts: The Audio input , Audio output, RF input , RF output and Mixer. The circuit works as both receiver and transmitter, you can switch the state by pressing the DPDT button. The walkie-talkie is in receiver mode by default. Users will press the button to switch to transmitter mode and release the button to go back to receiver mode. Additonally, the antenna is used to receive the audio signal.

Features:

Short distance communication
A low voltage audio amplifier LM386 has been utilized in both audio input and output to amplify the signals.
Mixer IC SA612AN that mix a input signal with 8Mhz signal to achieve demodulation
Crystal oscillator that works with mixer
RF Antenna
OpAmp NE5537 that has a higher bandwidth frequency response
Low voltage and portable with 9V / 500mAh Battery

Schematic

BOM

Layout

Front PCB layout

Bottom PCB layout

3D model of PCB

Progress: PCB without components

PCBs arrived from JLCPCB

Update: Since the components is delayed, we have do the soldering. Once it arrvied, we will solder those compenents on and test the fucntionality of our project

Future Improvement

We should try probing the tesing point to check if there are siginificant distortion in our signal.
Further research and learning for how to layout RF circuit should be done
We want to have a 3D printing case for our walkie talkie. We might ask for help from our ME friends!

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