BUILD CARD · EASY
Hear the Motor
Recreate manual Project 30 by putting a motor and speaker in the same current path.
- Time
- 15 min
- Age
- 8+
- Pieces
- 6
- Board
- 10×7
- Build and check a 10×7 snap-grid circuit from a visual diagram.
- A speaker makes variations in motor current audible as the shaft runs.
02 / PARTS CHECK
Parts list
- 1×7-snap wireconnector
- 1×3-snap wireconnector
- 1×Motoroutput
- 1×Speakeroutput
- 1×Slide switchswitch
- 1×3V two-cell battery holderpower
03 / ASSEMBLY
How to build the circuit
- 1
Disconnect the battery and clear the base grid before placing any part.
- 2
Match the final diagram one grid position at a time, placing connecting wires and lower layers first.
- 3
Check the direction of every LED, diode, transistor, battery, and other terminal-sensitive part.
- 4
Press every shared snap firmly, check that no wire shorts the battery, then connect power last.
04 / FIELD NOTES
How it works
The motor current is not perfectly steady.
The speaker converts current variations into audible vibration.
The sound changes as motor speed changes.
Explore more motor circuit projects →
05 / TEST
Test and expected result
- What to do
- Close the switch and listen while the motor accelerates.
- What to expect
- The speaker reveals changing motor current as audible sound.
06 / SAFETY
Build smart
- Use only the 3V two-cell battery holder.
- Never connect the battery terminals directly together.
- Disconnect the battery before moving any component.
- Keep fingers and loose objects away from the motor shaft.
07 / TROUBLESHOOTING
If it does not work
- Press every overlapping snap down firmly.
- Check the battery direction and replace weak batteries.
- Compare every component position with the final diagram.
08 / FREQUENTLY ASKED QUESTIONS
Questions about this circuit
What is the main idea behind this circuit?
A speaker makes variations in motor current audible as the shaft runs.
What should I check first if it does not work?
Press every overlapping snap down firmly.
09 / RELATED BUILDS
Try a similar circuit
Continue with another build that shares the same components, ideas, or difficulty.
Lamp and Fan in Series
Recreate manual Project 27 with the lamp and motor sharing one current path.
Motor Sound with LED
A protected LED variation of manual Project 31 that makes motor-current changes visible.
Lamp and Fan in Parallel
Recreate manual Project 29 with separate lamp and motor branches across the battery.