The Flyback Transformer Design and Calculator, also known as the Flyback Switch Mode Regulator Calculator, is an online tool for electrical and power electronics designers. It allows you to calculate key parameters required for flyback converter design, including transformer turns ratio, primary inductance, charge and discharge periods, and other critical values. This calculator helps streamline the design and analysis of flyback transformer circuits for switch-mode power supplies.
Introduction
An electric coil (also known as an electromagnetic coil) is a fundamental electrical component consisting of conductive wire wrapped around a core. The core can be ferromagnetic (like iron or steel) to amplify the magnetic field, or it can be air/non-magnetic for specific applications.
How it Works: When electric current flows through the wire, it generates a magnetic field around the coil. This interaction allows coils to perform three main functions:
Coils are categorized based on their core material, winding shape, and function. Below are the most common types used in electronics and engineering.
To design a coil, you must calculate physical properties like wire length, resistance, and the number of turns.
Key Variables:
1. Cross-Sectional Area of Wire () (Where is the radius of the wire)
2. Radius of Middle of Coil () Used to calculate the average length of one turn.
3. Total Wire Length ()
4. Electrical Power () (Where is Voltage and is Current)
5. Ohm's Law (Voltage & Resistance)
The number of turns () is critical for determining the strength of the magnetic field.
Inductance () measures the coil's ability to store energy. For a simple air-core coil, the approximation is: .
Use this chart to determine the resistance and diameter of copper wire for your coil. Thicker wire (lower AWG) handles more current but takes up more space.
| AWG | Diameter (mm) | Resistance (/m) | AWG | Diameter (mm) | Resistance (/m) |
|---|---|---|---|---|---|
| 4/0 | 11.7 | 0.000161 | 22 | 0.644 | 0.0530 |
| 3/0 | 10.4 | 0.000203 | 23 | 0.573 | 0.0668 |
| 2/0 | 9.26 | 0.000256 | 24 | 0.511 | 0.0842 |
| 1/0 | 8.25 | 0.000323 | 25 | 0.455 | 0.106 |
| 1 | 7.35 | 0.000407 | 26 | 0.405 | 0.134 |
| 2 | 6.54 | 0.000513 | 27 | 0.361 |
| 0.169 |
| 3 | 5.83 | 0.000647 | 28 | 0.321 | 0.213 |
| 4 | 5.19 | 0.000815 | 29 | 0.286 | 0.268 |
| 5 | 4.62 | 0.00103 | 30 | 0.255 | 0.339 |
| 6 | 4.11 | 0.00130 | 31 | 0.227 | 0.427 |
| 7 | 3.66 | 0.00163 | 32 | 0.202 | 0.538 |
| 8 | 3.26 | 0.00206 | 33 | 0.180 | 0.679 |
| 9 | 2.91 | 0.00260 | 34 | 0.160 | 0.856 |
| 10 | 2.59 | 0.00328 | 35 | 0.143 | 1.08 |
| 11 | 2.30 | 0.00413 | 36 | 0.127 | 1.36 |
| 12 | 2.05 | 0.00521 | 37 | 0.113 | 1.72 |
| 13 | 1.83 | 0.00657 | 38 | 0.101 | 2.16 |
| 14 | 1.63 | 0.00829 | 39 | 0.0897 | 2.73 |
| 15 | 1.45 | 0.0104 | 40 | 0.0799 | 3.44 |
| 16 | 1.29 | 0.0132 | 41 | 0.0711 | 4.34 |
| 17 | 1.15 | 0.0166 | 42 | 0.0633 | 5.47 |
| 18 | 1.02 | 0.0210 | 43 | 0.0564 | 6.90 |
| 19 | 0.912 | 0.0264 | 44 | 0.0502 | 8.70 |
| 20 | 0.812 | 0.0333 | 45 | 0.0447 | 10.98 |
| 21 | 0.723 | 0.0420 |
Thinner wires increase resistance per meter (e.g., 0.0333 Ω/m for 0.812mm diameter). Thicker wires allow fewer turns per layer but reduce resistance. The calculator dynamically adjusts results based on input wire diameter
This optional input calculates voltage (V = I * R) and power (P = I * I * R) at the specified current. It helps designers evaluate thermal limits and ensure safe operation without overheating
Total length depends on the average coil diameter and number of turns. The formula uses: Length = π * (Bobbin Diameter + Wire Diameter) * Number of Turns, with adjustments for winding density
It focuses on air-core coils and single-layer windings. For cores like iron or ferrite, permeability and hysteresis losses require advanced tools beyond this calculator's scope
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