sparkfun Weevil Eye Owner's manual

The Weevil Eye kit is an introductory electronics kit designed to help the novice electronics
enthusiast learn about things like soldering and resistance. The Weevil Eye is designed
to look like a little beetle whose eyes glow in accordance with the ambient light
level – the less light detected, the brighter the friendly weevil’s eyes will glow. There is
no programming involved and all soldering is beginner friendly, so this kit is perfect for
the embedded electronics novice.
Kit includes:
• Weevil Eye PCB
• Red Diffused 5mm LEDs (qty 2)
• 47k Ohm Resistor
• 220 Ohm Resistors (qty 2)
• Transistor (2N3904)
• Miniature Photocell
• Coin Cell Battery Holder
• 20mm Coin Cell Battery
Kit Information & Instructions
Weevil Eye
WARNING:
Please wear safety goggles. This kit requires soldering and clipping leads.

Don’t: Use the very tip of the iron.
Do: Use the side of the tip of the iron, “The Sweet Spot.”
Do: Touch the iron to the component leg and metal ring at the
same time.
Do: While continuing to hold the iron in contact with the leg and
metal ring, feed solder into the joint.
Do: Use a sponge to clean your iron whenever black oxidization
builds up on the tip.
Don’t: Glob the solder straight onto the iron and try to apply the
solder with the iron.
SOLDERING TIPS SOLDERING TIPS
Solder flows around the leg and fills the hole - forming a
volcano-shaped mound of solder.
Error:
Solder balls up on the leg, not connecting the leg to the metal ring.
Solution: Add flux, then touch up with iron.
Error: Bad Connection (i.e. it doesn't look like a volcano)
Solution: Flux then add solder.
Error: Bad Connection...and ugly...oh so ugly.
Solution: Flux then add solder.
Error: Too much solder connecting adjacent legs (aka a solder jumper).
Solution: Wick off excess solder.
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1
Locate the 47k Resistor. It will be color-coded with stripes — yellow,
purple, then orange.
2
Bend the legs downward.
Locate the 47k Resistor
position on the board.
47K 220 220
QUICKSTART - YOUR FIRST COMPONENT [ STEPS 1 T0 12 ]
3
4
Insert the resistor into the PCB.
5
Push the resistor in so it is nearly flush with the board.
6
Slightly bend the legs outward to hold it in place.
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8
Feed solder into the joint.
7
Flip the board over. Hold the soldering iron’s “sweet spot” so it
touches both the leg and the metal ring. Hold for two seconds.
11
Solder the next leg into place.
12
Clip off the excess.
10
Your solder joints should look like this - a tiny volcano.
9
Pull solder away first.
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Steps highlighted with a yellow warning triangle represent a
polarized component. Pay special attention to the component’s
markings indicating how to place it on the board.
Now that you’ve successfully soldered in the
resistor, use the same method to place and solder
the rest of the components.
Photocell: This part fits in the slot marked at the bottom of the
board. Orientation for this device doesn’t matter.
Transistor (2N3904): It’s the only three-pin device and it’s black.
Notice the silkscreen (white print on the board) resembles a half
circle. Make sure to place the transistor in the holes with regard
to the silkscreen. The round side on the board should match the
round side of the transistor.
220 Ohm Resistor: Match the resistors to the correct positions
on the board, then solder.
Photocell
15
Transistor
14
220 Ohm Resistor x 2
13
CONTINUE WITH THE TOP OF THE BOARD [ STEPS 13 T0 16 ]
47K 220 220
TOP OF BOARD

47K 220 220
TOP OF BOARD
LEDs x 2
16
Remember highlighted components are polarized.
CONTINUE ON THE TOP OF THE BOARD
LEDs: Insert the LEDs into the front of the board. Each LED
has a short leg and a long leg. The short leg goes into the hole
labeled “ .” Also make sure it sits flush with the PCB. Then
solder into place.
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Battery Clip
17
Remember highlighted components are polarized.
NOW WORK ON THE BOTTOM OF THE BOARD
Battery Clip: Turn the board over and align the battery clip with
the white footprint on the Weevil Eye’s back. Make sure the legs
stick through the board and that the part is laying flat. Solder the
battery clip’s legs into place from the top of the board.
BOTTOM OF BOARD

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Once the Weevil Eye is soldered, we can test the board’s functionality.
• Put the 20mm coin cell battery into the battery holder, positive
side up.
• If it’s dark, you should see the LEDs light up. If not, cover the sensor
with your finger to test.
• If your Weevil’s eyes aren’t lighting up, don’t worry! Start with some
simple troubleshooting. Check your solder joints to make sure your
components have a good connection to your board – solder should
flow into the board and not ball up around the component’s pins. Also
check to make sure your transistor and LEDs are correctly oriented!
QUICK TEST INSTRUCTIONS

© SparkFun Electronics, Inc.All Rights Reserved. The SparkFun Weevil Eye Kit features, specifications, system requirements,
and availability are subject to change without notice. All other trademarks contained herein are the property of their
respective owners.
Soldering
The tip of the iron is normally 700 °F, hot enough to melt metal. It is normal for
the handle of the soldering iron to heat up a bit. Hold it like a pencil and move
your hand further away from the tip if the heat is uncomfortable. The solder
smokes because the rosin inside the solder is burning off - it’s not harmful.
LEDs
Light-emitting diodes (LEDs) are like light bulbs, but much smaller and a lot
more efficient.
Photocell
A photocell changes resistance depending on the amount of light it is
exposed to. These little sensors make great ambient light triggers.
Learning More