Step 1: Get Your Parts
You will need [digikey part numbers in brackets]:
(1) Easy Button
(1) ISD1610 Voice recorder [ISD1610BSY-ND]
(1) Electret microphone [P9925-ND]
(1) Pushbutton [EG1826-ND]
(1) 1k Resistor [1.00KdXBK-ND]
(1) 80.6k Resistor [80.6KXBK-ND]
(3) 4.75k Resistor [4.75KXBK-ND]
(5) 0.1uF Ceramic capacitor [BC1101CT-ND]
(5) 4.7uF Caramic capacitor [445-2854-ND]
You will also need these supplies:
Wire (I used 24 AWG stranded and 30 AWG solid)
Glue (I used 5 minute epoxy)
And these tools:
Step 2: Disassemble
Remove the two screws holding the circuit board down, remove the circuit board and the spring steel below it.
Finally, remove the last four screws and the bracket they hold down so we can see the speaker and bottom plate.
This might sound complicated, but just take everything apart.
Step 3: Rework the Pushbutton
In the picture below, remove the items circled in red: the power wires, an electrolytic capacitor, and a resistor.
Next, make small, complete cuts through the traces where shown circled in green.
Finally, attach wires to the pushbutton at the test points where the yellow arrows show. Feed the wires down through one of the holes next to the button.
Step 4: Adding the Microphone
Looking at the bottom you will see two metal rods that are glued on either side of the speaker. Pry one of them out so we can put our hardware there. You will also have to hack out the vertical brace that the rod was glued to.
Next, drill two holes, as shown in the picture below. One should be just smaller than the microphone and one should be just bigger than the switch's actuator. Carefully glue the microphone and switch in place as shown. This is also a good time to add some pieces of wire to them.
Put the big plastic bracket back in place over the speaker and fasten it down with the four screws removed earlier.
Step 5: Building the Circuit
Following the schematic, add all the parts, I like to start with the big wires first, in this case the power and ground and the two speaker wires. Then add all the capacitors, then connect power and ground to each Vcc and Vss with short pieces of wire, then add the resistors. Finally, connect the microphone and two switches.
Step 6: Assemble
To record a message, hold down the pushbutton on the bottom and speak into the microphone. It is reasonably sensitive and has automatic gain control so you don't have to yell into it. Now press the big button on top to play back your message. It is similar in volume to the original, but a lot more fun.