1. Industry Average for a Custom Transformer Sample: 2–4 Weeks
That’s the honest number.
You send a specification to a transformer supplier. They review it, check material availability, slot it into production, make the sample, test it, and ship it. If the core or bobbin isn’t in stock, add another week for procurement.
Most engineers accept this as normal. They plan their project timeline around it.
But here’s the reality: the sample itself takes about 30 minutes of actual production time — winding, terminating, assembling, testing. The remaining 13+ days are waiting. Waiting for material, waiting for the production schedule to open up, waiting for QC to have bandwidth.
At Linkpower, we looked at this and asked: what if we removed the waiting?
2. Where the Waiting Comes From
Let’s break down a typical 3-week sample lead time:
| Step | Typical Time | Where the Time Goes |
| Spec review & confirmation | 1-2 days | Back-and-forth emails, unclear requirements |
| Material check & procurement | 3-7 days | Core out of stock, special wire gauge needs ordering |
| Production scheduling | 2-5 days | Sample gets queued behind production orders |
| Winding & assembly | 0.5-1 day | Manual setup, tooling changeover |
| Testing | 0.5-1 day | QC queue, test fixture setup |
| Packing & shipping | 0.5-1 day | Logistics coordination |
The actual value-add steps (winding through testing) account for less than 10% of the total lead time. The rest is friction.
Most suppliers can’t fix this because their production lines are optimized for volume, not flexibility. A sample disrupts the flow — it requires different materials, different tooling, and stops the operator’s rhythm.
That’s understandable. But it’s also fixable.
3. What We Did Differently
We set up a dedicated sample production line. It’s not the same line that runs our 10,000-piece production orders.
What’s different about it:
- Pre-stocked material library. The 20 most common core shapes (EE, EF, PQ, RM, EPC) and wire gauges (0.1–1.0mm) are kept on the shelf. No waiting for procurement.
- Dedicated sample operators. They don’t stop to handle production orders. Their only job is samples.
- Pre-configured winding programs. Our automatic winding machines store parameter files for common turn counts and wire gauges. A new spec doesn’t mean reprogramming from zero — we load a close match and adjust.
- Universal test jigs. Instead of custom fixtures for every part number, we use adjustable test adapters that cover 90% of our transformer portfolio. Hi-Pot, inductance, turns ratio, DC resistance — all test-ready within minutes of the sample coming off the line.
This doesn’t require expensive equipment. It requires designing the workflow around speed, not just unit cost.
4. The 24-Hour Timeline — Real Numbers
Here’s what a recent 24-hour sample looked like. Customer needed a custom PQ2620 transformer for a GaN-based power supply prototype.
| Time | Step | Notes |
| 09:00 | Spec received via email | Customer sent parametric spec (turns ratio, inductance, isolation voltage) |
| 09:15 | Engineering review | Feasibility check — core selection, wire gauge, bobbin availability |
| 09:30 | Material pulled | PQ2620 core, Grade 2 wire, pins from pre-stocked shelf |
| 09:45 | Winding program loaded | Adjusted from existing PQ2620 file — 3 parameter changes |
| 10:00 | First sample wound | Automated winding, 30 turns, 2 sections |
| 10:15 | Termination & assembly | Pins soldered, core assembled, tape applied |
| 10:30 | Testing | Inductance, DCR, turns ratio, Hi-Pot (all passed) |
| 11:00 | Second sample | Same process, for customer verification |
| 15:00 | Third sample with iteration | Customer asked for higher inductance — adjusted air gap, re-tested |
| Next day 09:00 | Packed & shipped | Three samples with test reports |
Total elapsed time from spec receipt to shipment: 24 hours. Actual production time per sample: ~45 minutes.
The customer received working samples, confirmed electrical performance, and placed a pilot production order the same week.
5. Fast Doesn’t Mean Sloppy
A common concern when we say “24-hour samples” is quality. Let’s address that directly.
Every sample goes through the same electrical tests as a production unit:
- Inductance (L) at specified frequency
- DC resistance (DCR)
- Turns ratio
- Hi-Pot (dielectric strength)
- Insulation resistance
The results are recorded on a sample test report that goes with the shipment. We don’t skip steps to save time.
What we do skip is the waiting. The testing equipment is already set up. The operator doesn’t need to search for the right fixture. The report template is pre-filled with the spec values — the operator only fills in the measured results.
The difference between a sample and a production unit is documentation depth (no full PPAP for samples) and statistical sampling (one-off vs. batch). The electrical performance is the same.
📌 For a breakdown of our full production quality system, see our Quality page.*
6. When 24 Hours Isn’t Possible (Be Honest)
Not every sample can ship in 24 hours. Here’s when it takes longer:
- Non-standard core shape. If the core needs to be custom-manufactured (not from stock), add 5-10 days.
- Exotic wire types. Litz wire, self-bonding wire, or extreme gauges may need sourcing.
- Complex multi-winding designs. Transformers with 6+ windings or multiple taps require more setup time.
- Full AEC-Q200 qualification samples. That’s not a 24-hour process — component-level stress testing takes weeks.
When a customer requests a sample, we give an honest timeline on the first reply. If it’s stock-compatible, we say 24 hours. If not, we say what’s realistic. Nobody benefits from a promise we can’t keep.
📌 For samples requiring automotive-grade qualification, see our IATF 16949 guide.*
7. FAQ — Quick Answers
Q: Does Linkpower charge for samples?
Depends on complexity and quantity. Standard samples (1-3 pcs of a common design) are typically free for qualified prospects. Custom or large-quantity samples may carry a nominal fee, refundable with production orders.
Q: What information do you need to start a sample?
A parametric spec sheet is ideal. Minimum: turns ratio (or primary/secondary inductance), operating frequency, isolation voltage, and physical dimensions (core type or max footprint). If you have a data sheet from a competitor part, send it — we can work from that.
Q: Do sample test reports include raw data?
Yes. Measured values for L, DCR, turns ratio, and Hi-Pot are included. We don’t just mark “pass/fail” — you get the actual numbers.
Q: Can you match the electrical performance of a competitor’s part?
Usually yes. We reverse-engineer competitor samples using inductance, turns ratio, and core material analysis. If the physical footprint matches, we can make an electrically equivalent part.
Q: How does sample quality compare to production quality?
The same electrical tests, the same acceptance criteria. The difference is in documentation and lot traceability — production units get full batch records and material lot traceability.
Q: What’s the typical sample-to-production timeline?
Sample: 24 hours to 1 week. Pilot run (100-500 pcs): 2-3 weeks. Full production: 4-6 weeks depending on volume and material lead times.
Q: Can you do samples for custom inductors, not just transformers?
Yes. The same 24-hour service applies to inductors (SMD shielded, through-hole, high-current) that use standard core materials.
8. Bottom Line
24-hour transformer samples aren’t a gimmick. They’re the result of a process designed to remove waiting, not to cut corners.
When you’re evaluating a transformer supplier, ask them how long a sample takes. If they say 3-4 weeks, ask why — it’s usually not because the winding takes that long. It’s because the system isn’t set up for speed.
If speed matters for your project, send us your spec. We’ll tell you honestly whether it’s a 24-hour job or something that needs more time.
📌 Not sure what to include in your spec? See our guide on How to Write a Custom Transformer Specification.*
