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Build Instructions, Page 4 / 6



Step 7: Piezo Speaker

Insert speaker SP1 into the marked holes on the board. This part can also go in either way. Carefully bend the legs a little and flip the board over. Solder the connections and trim the legs.

Bend leads and solder partLocation of piezo

It’s time to check our work before proceeding onto the next step. Check the resistance between the power and ground using the same test points as before. The resistance should still be in the megaohm range. If it isn’t, there is likely a short between some solder joints. Check your work and try again.

Step 8: Adding the microcontroller

The microcontroller only goes in one way. There is a notch on one of the ends. This matches the notch on the white diagram on the board. Insert the microcontroller carefully. If the legs are too spread apart, they can be fixed using a simple technique: You can slightly but uniformly bend the legs by pressing the chip against the table as shown in the photo below.

Carefully bend the leads of the pinLocation of microcontroller

Insert the microcontroller all the way. Check the resistance: If it’s still high, add the batteries. You should hear a beep, indicating that the microcontroller is working! Take the batteries out. If you don’t hear a beep, remove the batteries and double check your work.

Step 9: More resistors

Place the 1k resistors, labeled with brown-black-red, into the resistor areas labeled R6, R7, R8. Use the white circle to guide their placement into the board. Solder each resistor and trim all the legs.

Solder all the leadsLocation of R6, R7, R8

Step 10: Potentiometer

Next, put the potentiometer into the board, above the label RV1. The potentiometer looks like a little blue cube with a yellow dial on the top, and controls the contrast of the display. Solder and trim the legs.

Solder all the leadsLocation of potentiometer