Transformer Calculator
Calculate secondary voltage, turns ratio, and secondary current for an ideal transformer.
How it works
- 1Enter the primary voltage (Vp) and the primary winding turns (Np).
- 2Enter the secondary turns (Ns) and the primary current (Ip).
- 3The calculator applies Vs = Vp × Ns/Np and Is = Ip × Np/Ns to show secondary voltage, ratio, and current.
Use cases
- Designing a power supply that needs a specific output voltage from the mains.
- Verifying a step-down or step-up transformer specification before use.
- Demonstrating the link between voltage, current, and winding turns.
Frequently asked questions
How is the secondary voltage calculated?
The ideal transformer relation is Vp/Vs = Np/Ns, so Vs = Vp × (Ns ÷ Np). A 240 V primary with a 1000:500 ratio gives 120 V.
Why does stepping voltage down raise the current?
An ideal transformer conserves power (P = V × I). Halving the voltage doubles the current, so Is = Ip × Np/Ns.
What does the isolation type mean?
When Np = Ns the ratio is 1 and the output matches the input voltage, while still giving galvanic isolation between the two circuits.
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