OPTIONAL CHALLENGE 08 · BASIC ELECTRONICS
Mechanical arrangement can reverse a signal rule without changing the output circuit. This model signals opening rather than closing.
Make controls and play
Your new skill: Mechanical arrangement can reverse a signal rule without changing the output circuit. This model signals opening rather than closing.
Revisit the skill you will reuse: Previous main-path mission
Match the names to your parts before you build. New parts appear when you first need them. You can point, say the name or show a grown-up.
A battery supplies energy that can make a light glow or a motor turn. A holder keeps its connections in place.
Look for: Find the + and - marks and the matching holder or snap connector.
Before using it: Use only the supply named in this mission. Never join + straight to -; disconnect before rewiring.
Your turn: With power disconnected, trace the path from + through the parts and back to -.
A wire makes an electrical connection between two points. A clip lead grips a terminal.
Look for: Jumpers have small plug ends; clip leads have metal jaws. Colour helps us track a connection.
Before using it: Colour does not change a wire's job. Check both ends and keep bare metal away from other terminals.
Your turn: Follow one wire from start to finish and name what it joins.
This reusable building board joins some holes with hidden metal strips, so we can connect parts without soldering.
Look for: Find the centre gap, row numbers and power rails. The gap separates the two halves.
Before using it: Five holes in one numbered strip usually join; the strip across the gap does not. Some power rails have a break. Match your board diagram.
Your turn: Point to two holes on the same connected strip, then two that are separated by the gap.
A resistor limits current in a path. Beside our LED it helps protect the light from too much current. Its resistance is measured in ohms.
Look for: Look for a small body with two legs and coloured bands; match its labelled value to the mission.
Before using it: Use the labelled 2.2 kΩ, 2.7 kΩ or 520 kΩ value specified. A resistor can face either way. Never replace LED current limiting with wire.
Your turn: Point to the resistor in the LED path. Explain why replacing it with a plain wire is not our test.
An LED turns electrical energy into light and works in one direction. We use it to show what a circuit is doing.
Look for: An untrimmed ordinary LED often has a longer anode leg and a shorter cathode leg. A flat rim often marks the cathode.
Before using it: Confirm polarity with the part card if legs are trimmed. Use the mission's resistor in series; never connect an LED straight across the battery.
Your turn: With power off, identify the two legs and point to its protective resistor.
WHAT YOU'LL USE
Reuse kit parts between projects. Household materials are listed separately. Match every value, variant and rating before connecting power.
BEFORE YOU BUILD
Disconnect power before every change. Never join battery positive directly to negative. Keep the specified LED resistor in place. Keep metal out of mouths and away from mains sockets. Stop and ask an adult if any part becomes warm or smells unusual.
YOUR REWARD
PREDICT BEFORE YOU BEGIN
Predict the result before testing. You can say it, draw it or point. What evidence would change your prediction?
BEFORE YOU BUILD
Adult setup check: Adult mechanical check; no spring contact may expose a battery short. If this check cannot be confirmed on your actual parts, read and explore the concept only; do not power the build.
YOUR CHALLENGE
NEW POWER-UP
Mechanical arrangement can reverse a signal rule without changing the output circuit. This model signals opening rather than closing.
Practise first: 7. Reuse the familiar circuit before changing one feature.
Each coloured strip is one connected group. Different numbered rows stay separate. This explains the board; use the mission’s exact connection reference for component positions. Check rail breaks on your supplied board.
Three repeatable door-opening signals with a free-moving card tab. This is a learning model, not a security device.
Mechanical arrangement can reverse a signal rule without changing the output circuit. This model signals opening rather than closing.
Why does removing the card tab turn the light on? It lets the conductive contacts touch and completes the path.
CONNECTION MAP
BUILD PATH
STEP 1 OF 4
Make a gentle folded-paper spring with two foil contacts that rest together. Test touching and separated states before adding the door.
A video demonstration will appear here when it is ready. You can follow the written step now.
Make a gentle folded-paper spring with two foil contacts that rest together. Test touching and separated states before adding the door.
WHAT'S REALLY HAPPENING?
Mechanical arrangement can reverse a signal rule without changing the output circuit. This model signals opening rather than closing.
FAIR-TEST CHALLENGE
Change only the feature named in this project; keep the supply, parts and observation conditions the same. Repeat the comparison.
WHEN IT DOESN'T WORK YET
Likely cause: An open path, wrong node, polarity mismatch or a part variant that needs review.
Try this first: First prove the contacts work without the model door; then adjust only the tab position.
Likely cause: The setup needs adult inspection.
Try this first: Disconnect immediately. Do not retry until the fault is identified.
CLEAN, RESET AND STORE
Switch off and disconnect all power. Let moving parts stop. For capacitor projects, discharge through the 2.2 kΩ resistor for ten seconds with battery disconnected. Return loose parts to the box.