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The problem
Wireless power transfer looks simple in theory — two coils, one magnetic field — but the physics hides in resonance and alignment, and most student builds stop at "the LED lit up" without explaining why it lit. A receiver coil that glows at 1 cm and goes dark at 6 cm is a better teacher than any equation, and this kit makes that lesson direct and measurable. Its distinguishing instrument is a 10-LED bar-graph indicator wired to the rectified receiver voltage, so every change in distance, angle or alignment registers instantly on a live coupling meter. Around it sits a complete resonant inductive link: a ZVS-style high-frequency driver board, hand-wound enamelled-copper transmitter and receiver coils tuned with capacitors to resonance, and an LED demo load. The build is documented as a measurement exercise — winding the coils, tuning to resonance, calibrating the indicator, then recording bar-graph level against distance and misalignment to plot the efficiency-vs-distance curve that anchors the report.
Regulated 12 V bench supply powering the driver board.
Follow the working sequence
How it works
- A 12 V DC supply powers the ZVS-style driver board, which switches the transmitter coil at its resonant frequency (approximately 100–200 kHz, design target).
- The coil's alternating magnetic field threads the receiver coil across the air gap, inducing an AC voltage by mutual induction.
- Series capacitors tune both coils near resonance, so the link peaks at the driver frequency — detuning collapses transfer, which the student verifies deliberately.
- On the receiver side, a bridge rectifier and filter convert the captured AC to DC for the LED load and the charging-demo output.
- A tap of the rectified receiver voltage feeds the LM3914-style bar-graph driver, lighting 0–10 LEDs in proportion to coupling strength.
- Sliding the receiver coil sideways or lifting it drops the lit bars in real time; the student records bar level at fixed positions to build the efficiency-vs-distance curve.
- During assembly, resonant capacitors are selected and the indicator's full-scale point is calibrated with the buyer's own multimeter, following the included procedure.
Tech stack:
- ZVS-style resonant driver board (MOSFET switching stage)
- Hand-wound enamelled copper coils (28 SWG, design values)
- LM3914-style 10-LED bar-graph indicator
- Bridge rectifier + filter (receiver DC stage)
- 12 V DC regulated bench supply
- Acrylic coil mounts + solderless breadboard assembly
- Multimeter · oscilloscope (tuning and calibration)
- Resonance math: LC tuning and coupling coefficient (report)
| Parameter | Value |
|---|---|
| Input supply | 12 V DC regulated (datasheet value) |
| Driver frequency | Approximately 100–200 kHz (design target, ZVS-style stage) |
| Transmitter coil | Approximately 60 turns, 28 SWG enamelled copper, 8 cm diameter (design value) |
| Receiver coil | Approximately 35 turns, 28 SWG enamelled copper, 6 cm diameter (design value) |
| Usable transfer distance | Up to approximately 8 cm (expected; output becomes negligible beyond) |
| End-to-end efficiency | Approximately 20–30% at close coupling (design target, falls rapidly with distance) |
| Alignment indicator | 10-LED bar graph, 0–10 scale driven by rectified receiver voltage |
| Demo load | LED lamp; 5 V charging-demo output, approximately 1 W maximum (design target) |
| EMI guidance | Keep at least 30 cm from sensitive receivers during demos (design guidance) |
| Coil mounts | Acrylic disc mounts on perforated base |
Project features
- [LED bar-graph alignment indicator] The project's distinguishing feature: a 10-LED bar graph (LM3914-style driver) fed by the rectified receiver voltage, showing coupling strength live on a 0–10 scale. Every alignment change registers instantly.
- [Resonant inductive coupling] Transmitter and receiver coils are hand-wound from enamelled copper wire and tuned with capacitors to the driver's resonant frequency, so transfer peaks sharply at resonance — exactly the viva's favorite question.
- [High-frequency driver stage] A ZVS-style MOSFET driver board switches the transmitter coil at approximately 100–200 kHz (design target), with onboard terminal blocks for stable bench operation.
- [LED demo load with charging-demo output] The receiver powers a bright LED lamp directly; a regulated 5 V charging-demo output (approximately 1 W maximum, design target) is included for low-power devices — honestly limited, see Limitations.
- [Coil winding and tuning guide] Step-by-step coil winding (turn counts, formers, insulation) plus the resonant-capacitor selection and indicator calibration procedure the buyer performs on their own build.
- [Measurement-oriented build] Test points for multimeter and oscilloscope probing, with a plotting template to record bar-graph level versus distance and misalignment — the efficiency-vs-distance curve becomes the report's centerpiece.
- [Complete viva kit] Report PDF, PPT presentation and Q&A document covering resonance, coupling coefficient, alignment sensitivity and efficiency measurement.
What is included
- Working prototype: transmitter coil, receiver coil, driver board, LED bar-graph indicator, LED demo load
- Coil winding and assembly documentation with circuit diagrams
- Resonance tuning and indicator calibration procedure (buyer-run)
- Efficiency-vs-distance measurement and plotting template
- Project report PDF (resonance theory, build, measurements)
- PPT presentation for final review
- Viva Q&A preparation document (resonance, coupling, alignment, efficiency)
Limitations & prerequisites
- Usable distance is measured in centimeters: up to approximately 8 cm (expected) before the output becomes negligible — this is a near-field coupling demonstration, not room-scale charging.
- Efficiency is a design-target curve, not a measured claim: approximately 20–30% at close coupling, dropping below 10% beyond approximately 5 cm (expected).
- Alignment is the entire point of the kit: a lateral shift of half a coil diameter roughly halves the indicated coupling (expected); the indicator exists to make this visible.
- The charging-demo output is approximately 1 W (design target) — enough for a demonstration, not for fast-charging a phone.
- The high-frequency driver radiates around 100–200 kHz; keep the running kit at least 30 cm from AM receivers and sensitive instruments during demos.
- Coil turn counts and resonant capacitors are design values tuned per build — the buyer follows the included tuning procedure rather than inheriting a guaranteed figure.
- Not mains-powered and not a consumer charger; no safety certification; lab/demo use under supervision only.
Frequently Asked Questions
How does the alignment indicator work?
A tap of the rectified receiver voltage drives an LM3914-style 10-LED bar graph: more coupled energy means more lit LEDs. It responds instantly, so sliding the coil off-center visibly drops the bars — the student uses it as a live coupling meter during alignment experiments.
How far can it actually transfer power?
Usefully to about 8 cm (expected) before the LED load goes dim. Efficiency collapses with distance because near-field coupling weakens sharply as the gap grows — the kit's measurement section plots this curve instead of hiding it. Beyond that, the indicator reads zero to two bars — which is itself the demonstration.
What efficiency should I expect?
A design target of 20–30% at close coupling, falling fast with distance. The report presents this honestly as a curve measured from the buyer's own build, not a printed spec — plotting it is part of the project work. Misalignment hurts just as much: half a coil diameter off-center roughly halves the reading (expected), and the indicator makes that visible in real time.
Can it charge a phone?
Not meaningfully: the 5 V charging-demo output is about 1 W (design target), good for a demonstration, not for fast charging. The project is about coupling physics and measurement, and the page states this upfront so expectations stay honest. Treat the output as a measurement point for the load, not as a power bank.
Is it safe to build and demo?
The kit runs from a 12 V DC bench supply with no mains exposure, so the shock hazard is minimal; the main caution is RF noise around 100–200 kHz near sensitive receivers. Demos run under faculty supervision like any lab build.
Is this project suitable for a final-year project?
Yes, for Electronics, E&TC and Electrical programs. It teaches resonance, mutual inductance, driver design and measurement discipline, and the live alignment indicator gives examiners something concrete to probe in the viva. The hand-wound coils and tuning procedure give the student genuine build work to defend.
Components & software requirements
- ZVS-style resonant driver board (MOSFET switching stage)
- Hand-wound enamelled copper coils (28 SWG, design values)
- LM3914-style 10-LED bar-graph indicator
- Bridge rectifier + filter (receiver DC stage)
- 12 V DC regulated bench supply
- Acrylic coil mounts + solderless breadboard assembly
- Multimeter · oscilloscope (tuning and calibration)
- Resonance math: LC tuning and coupling coefficient (report)
Delivery information
Built-to-order project. Delivery timeline is shared after order confirmation based on current queue.
Support terms
Complete documentation, setup guide, and viva preparation included. Support for setup and explanation provided.
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