Free PCB is a free, open-source PCB editor for Microsoft Windows, released under the GNU General Public License. It was designed to be easy to learn and easy to use, yet capable of professional-quality work. It does not have a built-in auto router, but it can use the Free Route web-based auto router at www.freerouting.net. Some of its features are:
The layout for a small PCB is shown in the screenshot below.
| Preferred components | Select component values used in all designs and step size for ctr-n and ctr-m |
| Hot keys | Define hot keys for opening pages |
| Geometry | Handles: Circles, part of circles, triangles, squares, rectangles, trapezoid |
| Sound | Sound speed and perceived sound levels |
| Weather and air | %RH, dew point, air pressure and other weather related calculations |
| Periodic table | A periodic table with all elements, it has search functions and a few data for each element |
| Photo lens | Some lens calculations |
| Photo light | Some light calculations |
| Calculator | Can do all the usual stuff, including mathematics. |
| Tiny Calc | Can do the same as the entry line in Calculator, but is very small when pulled out. |
| Curve fit | Fits a curve to a collection of data points |
| Ohms law | Ohms law, impedance of capacitor and inductors, complex power |
| Ohms law 3 phase | Ohms law with complex power for 3 phase systems |
| dB | Decibel and neper, both power and voltage including volt/watt for a reference level |
| Charge curve | Capacitor/inductor charge/discharge with resistive, current and power loads (not all combinations supported) |
| Waveforms | Calculates RMS, mean, PEEK, DC, FFT for different waveforms. |
| Wires | Calculates resistance and power loss in wires, can also do conversion between USA and European units. |
| Cable calculations | Calculate frequence response of a cable |
| Fan cooling | Calculates how big a fan to get rid of some power. |
| Heat sink | Calculates junction temperature for specified power level and heat sink |
| Printed circuit board | Calculate micro strip, strip line, track resistance and current |
| Cable calculations | Simulate cables at low (audio) frequences |
| Capacitor design | Calculate capacitance of different geometries |
| Color codes | Convert between color codes and numeric values for many types of components. |
| Thermosensors | Calculates for PT100, NTC and all types of thermocouples |
| Air coil | Analyze or design an air core inductor |
| Leds | Color/wavelength of leds and design of circuits to drive leds from DC or AC. |
| Components type numbers | Tries to decode component codes |
| Power MOS | Turn on/off time and power loss estimation |
| MPU Timers | Calculates divide factors for up to five software timers |
| Integer math | Converts real numbers to fractions, calculates primes and other integer stuff |
| Serial communication | Timing and curves, use full when programming software uart's and IR rx/tx. |
| CRC and check sum | Calculate crc, check sum and modulus for data blocks, can also analyze a data block for what check sum/crc was used |
| Fo | Calculates Fo for RC, RL, RLC circuits |
| Series/parallel | Calculate/design series/parallel connection of resistors, capacitors and inductors |
| Charge time | Charge/discharge time for simple circuits (including 555). |
| Voltage divider | Design/analyze voltage dividers, can include component tolerance and load. |
| Two port | Conversion between different types of two ports. |
| 1. order filters | Analyze and design 32 different filter configurations |
| Attenuator network | Design different kind of attenuators |
| Power Supply | Analyze and design power supplies with 78xx and LM317 style regulators |
