Prepare
- Document essential functions, operating periods, resources and applicable component limits before work starts.
- Isolate energy sources, verify protective devices and identify work reserved for qualified trades.
D · Build a generator · 12–18 MIN
Understand how motion in a magnetic field produces voltage
In this lesson, you determine what “Understand how motion in a magnetic field produces voltage” must deliver in practice. You check the site conditions and the limits of the equipment, then record the result, the available reserve and a safe alternative.
Your learning progressSaved on this device.
Lesson guide
Procedure
Prepare, complete each step and verify the result.
Apply
- Complete “Step 1” and record each value together with its unit and operating condition.
- Before continuing, decide which warning signs require you to stop and which safe alternative remains available.
Verify
- Purpose, operating period and limits for understand how motion in a magnetic field produces voltage recorded
- Relevant input and output values measured with units
- Connection order and polarity checked against the data sheets
If the plan does not work
Adapt safely
- Reduce demand or test a smaller isolated system before increasing capacity.
- Use a documented safe fallback when a component, resource or measurement is uncertain.
Detect and correct errors
- A value without unit or operating condition must be measured again and recorded.
- On heat, smell, vibration, leakage or unstable readings: stop, isolate and identify the cause before restart.
Learning objectives
- Voltage is produced when the magnetic field and coil move relative to each other.
- Speed, magnet count and winding determine the voltage.
- When current flows, the generator becomes harder to turn and its voltage may fall.
What to check
Voltage is produced when the magnetic field and coil move relative to each other. Speed, magnet count and winding determine the voltage. When current flows, the generator becomes harder to turn and its voltage may fall.
REAL SYSTEM VIEW + TECHNICAL DETAIL 1/5
Parts and exploded drawing
Voltage is produced when the magnetic field and coil move relative to each other. Speed, magnet count and winding determine the voltage. When current flows, the generator becomes harder to turn and its voltage may fall.
REAL COMPONENT VIEW
The mechanical drive turns the rotor, whose magnetic field induces voltage in the copper windings.
| No. | Part | Function | Selection criterion |
|---|---|---|---|
| 1 | Base, brackets, bolts | supports and braces | rigid, flat, correctly bolted |
| 2 | Pillow blocks and shaft | guides the rotating axis | low-play and aligned |
| 3 | Crank/wheel and belt/chain drive | transmits and gears | matched speed range and load |
| 4 | Tensioner and coupling | sets tension/alignment | adjustable and guarded |
| 5 | Permanent-magnet motor | generates low voltage | rated speed, V and A documented |
| 6 | Guard and emergency isolator | prevents access and isolates | secure, tool-removable, reachable |
- 1Base / brackets / bolts
- 2Pillow blocks / shaft / coupling
- 3Crank or bicycle drive
- 4Pulleys / belt / tensioner
- 5Permanent-magnet motor / terminals
- 6Guard / emergency stop
Dependencies and limits
This project remains a 12/24-volt system galvanically isolated from the public grid. A crank or bicycle drives a permanent-magnet generator through guarded transmission, followed by rectification, a fuse, a suitable charge controller and only then a battery or approved DC load.
TECHNICAL DRAWING 2/5
Mechanical assembly: six states
Each panel shows the state after the step; orange marks the new part.
- Tool
- Drill, punch
- Target
- Hole pattern matches; base is flat
- Check
- Measure hole spacing
- Tool
- Spanners, torque wrench
- Target
- Bearings secure, still adjustable
- Check
- Compare diagonals
- Tool
- Straightedge, feeler gauge
- Target
- Shaft rotates freely and aligns
- Check
- Turn three revolutions by hand
- Tool
- Spanners, square
- Target
- Motor parallel; travel available
- Check
- Straightedge across pulley faces
- Tool
- Tension gauge/ruler
- Target
- Belt centred, not overtight
- Check
- Check maker value/deflection
- Tool
- Screwdriver, test probe
- Target
- no access; isolator reachable
- Check
- Test stopping and access
- 1Drill base
- 2Bolt pillow blocks
- 3Insert and align shaft
- 4Motor bracket in slots
- 5Fit and tension belt
- 6Install guard and emergency stop
Plan in the right order
Derive gearing from drive and generator radii or tooth counts. Measure open-circuit voltage without a battery first, verify polarity and increase speed gradually with the contact guard fitted.
TECHNICAL DRAWING 3/5
Crank generator: side view and ratio
n₂ = n₁ × D₁/D₂; arrows show opposing pulley rotation.
| Driver diameter | 300 mm | Motor pulley | 50 mm |
|---|---|---|---|
| Crank speed | 60 min⁻¹ | Motor speed | 60 × 300 / 50 = 360 min⁻¹ |
- 1safe grip
- 2crank arm
- 3large pulley D₁
- 4small pulley D₂
- 5belt + bearing
- 6motor + guard
Check and safeguard operation
Mechanical input is limited and friction, generator, rectifier and controller reduce output. Plan conservatively, positively secure every component and route strain-relieved cables away from moving parts.
TECHNICAL DRAWING 4/5
Isolated 12/24 V schematic
Positive through both fuses, negative as return. Never charge a battery directly and unregulated.
- 1PM generator
- 2optional rectifier
- 3source-side fuse F1
- 4two-pole isolator S1
- 5charge/DC-DC controller
- 6V/A metering
- 7battery-side fuse F2
- 8compatible battery / DC load; strain relief
WARNING: Isolated extra-low-voltage system only.
Worked calculation or decision
Doubling speed in a given generator approximately doubles open-circuit voltage; loaded power remains limited by heat and drive input.
TECHNICAL DRAWING 5/5
Prohibited grid coupling
The crossed-out view is not an instruction: the project ends here.
- 1Generator
- 2No 230 V
- 3No household wiring
- 4No grid feed
WARNING: STOP: no socket, house wiring or grid feed.
PROCEDURE
Carry out the lesson step by step
- 01 · Step 1
Voltage is produced when the magnetic field and coil move relative to each other.
- 02 · Step 2
Speed, magnet count and winding determine the voltage.
- 03 · Step 3
When current flows, the generator becomes harder to turn and its voltage may fall.
Materials and tools
- Documented permanent-magnet generator
- Rigid base, bearings and fully guarded belt or chain drive
- Rectifier, DC charge controller and battery-adjacent fuse
- Voltmeter, ammeter, emergency stop and eye protection
Safety and stop conditions
- Before intervention stop, disconnect the battery and wait for standstill. Keep hair, clothing and fingers away from shafts, spokes, belts and chains.
- Never energise house wiring, a socket or the public grid; never improvise a mains inverter. Charge batteries only through chemistry-specific control within temperature limits.
Typical mistakes
- Using a stated value for “Understand how motion in a magnetic field produces voltage” without checking its unit and the conditions under which it applies
- Buying or connecting components before confirming that they are compatible and adequately protected
- Assuming nominal capacity, peak output or one favourable measurement will be available continuously
- Continuing to operate despite unusual heat, smell, vibration, leakage, contamination or unstable readings
Final checklist
- Purpose, operating period and limits for understand how motion in a magnetic field produces voltage recorded
- Relevant input and output values measured with units
- Connection order and polarity checked against the data sheets
- Losses, temperature, seasonal effects and reserve included
- Safe shutdown and isolation tested before full load
- Result, unusual observations and next inspection recorded
DECISION CHECK
A measured value for “Understand how motion in a magnetic field produces voltage” differs from the plan and a warning sign appears. What should you do?
- Average it with the best earlier reading
- Stop the system, secure the affected section, find the cause and repeat the test under controlled conditions
- Increase the fuse rating or alarm threshold
Show answer
Correct answer: Stop the system, secure the affected section, find the cause and repeat the test under controlled conditions
Use this example for comparison: Doubling speed in a given generator approximately doubles open-circuit voltage; loaded power remains limited by heat and drive input. Do not resume operation until the cause of the warning and the relevant limit have been clarified.