CALCULATORS / MAGNETICS AND INDUCTIVE DEVICES

Transformer turns and volt-seconds calculator

Ideal transformer RMS turns ratio and load current.

magnetics-transformer.napkin / editable

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenario	secondaryVoltageV	primaryCurrentA
	23	0.1
	28.75	0.125

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

secondary voltage budget23.00 V✓ passes

BASELINE INPUTS

primaryTurns200 secondaryTurns20 primaryVoltage230 VloadCurrent1 A

CALCULATED

secondaryVoltage23 V

primaryCurrent0.1 A

Edits change the baseline source.

THE SOURCE

Edits below update the same model.

# Transformer turns and volt-seconds
# Scope: Ideal transformer RMS turns ratio and load current.
# Status: illustrative worked example; engineering review pending.
# Inputs are example values. Checks are editable example requirements, not standards.

primaryTurns = 200
secondaryTurns = 20
primaryVoltage = 230 V
loadCurrent = 1 A

secondaryVoltage := primaryVoltage*secondaryTurns/primaryTurns [V]
primaryCurrent := loadCurrent*secondaryTurns/primaryTurns [A]

check secondary voltage budget: secondaryVoltage <= 25 V

scenario alternative: primaryTurns = 160

Calculated from your source · not saved

Baseline · Baseline

secondary voltage budget23.00 V ✓ passes

alternative · alternative

secondary voltage budget28.75 V × fails

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

secondary voltage: secondaryVoltage = primaryVoltage*secondaryTurns/primaryTurns [V]
primary current: primaryCurrent = loadCurrent*secondaryTurns/primaryTurns [A]

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

primary turns: 200
secondary turns: 20
primary voltage: 230 V
load current: 1 A

Calculated

secondary voltage: 23 V
primary current: 0.1 A

Assumptions and limits

Ideal transformer RMS turns ratio and load current.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Transformer turns and volt-seconds. Inputs: waveform; frequency; core area; flux limit. Outputs: minimum turns; flux swing; turns ratio. Model scope: Magnetic-circuit approximations with calibrated material data. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

Inputs: waveform, frequency, core area, flux limit
Outputs: minimum turns, flux swing, turns ratio
Modes: calculate, compare, sweep
Drawing: Magnetic circuit and flux plot

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS