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Build Instructions, Page 4 / 5

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Step 8: Power Switch

Insert the power switch on the bottom corner next to the pushbuttons. The power switch is not polarized and can be installed either way. Solder down all five pads. You shouldn’t have to trim the leads. You might have to solder one pad first, then hold the switch flush against the PCB while re-melting that soldered pad. Be careful not to burn yourself with the hot switch case!

Installed Power SwitchLocation for power switch


Step 9: Piezo Buzzer

Place the piezo (SP1) into the board. You’ll notice it has two little pegs underneath that keep the case off the board. Use your finger to keep those pegs pressed firmly and squarely on the board. You can bend the leads to keep it in place, but you should still hold your finger on the top of the piezo while soldering it (or re-melting a soldered lead). Solder it, and clip the legs flush against the solder ball.

Soldering the piezoInstalled piezo


Step 10: Review

At this point, you should review your work. Are there any parts left over? Inspect your solder joints. Is there solder connecting any neighboring pads? There shouldn’t be! Are any component leads hanging too long? If there is any wire past the solder joint, trim it off with the diagonal pliers. If you have a multimeter (you should!), you can measure the resistance between the two pads for the battery holder. It should say there’s no connection, or have an extremely high resistance. If it says there’s a low resistance or a short, review your soldering again and look for the short. In the picture below, the multimeter is measuring resistance, and the value “0.L” means that the measured resistance is out of range, and is too large to measure. This means there is an open circuit (very large resistance) between the two battery pins, just what we want.

Check For ShortsTrim any long leads underneath the PCB