Selfie Ring Light Tutorial #7: Electronics

Step 2: Prep your Wires

In the wiring diagram, you can see the Red, Black and White (blue) wires.
The lengths of each section are indicated in cm. (The diagram is NOT to scale)

In this step we’ll cut, strip and join the wires together to match the circuit diagram.
This is surprisingly tricky to get right!

New Tool: Wire Strippers

These are great for: cutting wires and stripping the insulation off them.

  • The cutting part is close to the pivot.
  • There is a stripping part for each wire size.
    For our wires the 0.65 part is about right.
  • Clamp the wire in the stripping part of the jaws, and pull the wire to strip them.

New Tool: Side Cutters

These just cut, but are tougher than the wire strippers.
For the next step you can use either.

2.1: Cut wires

  1. Cut the red & black wires coming from battery box to 7 cm long.
  2. Cut a red wire 5 cm long.
  3. Cut a black wire 5 cm long.
  4. Cut a black wire 8 cm long.
  5. Cut a white wire 5 cm long.
  6. Cut a white wire 8 cm long.

Q: Does it matter if they’re a bit longer or shorter?
A: Do measure them, but don’t worry if the wires aren’t exactly the length above.

Q: Why those lengths?
A: To ensure the components and wires fit into the Selfie Ring Light enclosure.

2.2: Strip wire ends

With the 0.65 part of the Wire Strippers, grab one of the wires about 0.5 cm from one end.
Pull the wire, and the insulation should be stripped off the wire.
Maybe practice on a spare piece of wire first.

Repeat for both ends of each wire.
You should end up with a collection like this:

Uh Oh: Do your wires look like this?

  1. Too long! Use the Side Cutters to shorten the bare wires.
  2. Too short! Use the Wire Strippers a little further up to strip more insulation.
  3. Frayed! With your fingers pull the wire strands back into shape, twisting them a little to neaten them.

2.3: Twist Red and Black Wires Together

  1. Put the red battery box wire next to the 5 cm red wire, and twist the wire ends together.
  2. Put the black battery box wire next to the 5 cm black wire, and twist the wire ends together.
  3. Put the 8 cm black wire next to the other end of the 5 cm black wire, and twist the wire ends together.
  4. (Leave the white wires alone for now)

Each twisted wire joint should look something like this:

Important: The twisted-together wire ends need to fit through the small holes in the Digispark.
Make sure they fit before you continue to 2.4.

When all twisted together, your red and black wire sets  should look like this:

Just like in the wiring diagram.

2.4: Tinning Wires

Stranded wire (like we are using) will fray at the ends.
Tinning (melting a little bit of solder into the wire end) prevents this, and also secures the wire junctions.

Here are some well-tinned wire ends:

There is barely any excess solder on them, it “soaked” right into the wire strands.

If there is too much solder on the wires, they will not fit into the Digispark holes.
Uh Oh, here are some badly tinned wire ends:

  1. Blob of solder on the end! The rest of the wire is okay; use the side cutters to snip the blob off.
  2. Frayed Strands! The wire should have been tidied before tinning. Snip this bit off, then strip and re-tin it.
  3. Way too much solder! Try again with less solder. Snip this bit off, then strip and re-tin it.

For each of the ‘ends’ of the wires – the black ones, the red ones and the white ones;

  1. Put the wire (or wires) into the jaws of the helping hand.
    (For the red or black wire joints, put both wires into one of the jaws)
  2. Place the tip of the hot soldering iron onto the wire end for a few seconds, then
  3. Feed a little bit of solder onto the wire and iron, just enough to fill in the space between the strands and make it look silvery.
  4. Stop. No seriously, stop now, that’s enough solder.

Confirm that the tinned wires still fit through the Digispark holes:

(At least one end of each white wire, and the closest joint to the battery of the red and black wires)

Excellent, now to attach them to something useful….

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