About CircuitNote

CircuitNote is a free collection of electronics calculators, built by an electronic engineering student to replace the calculations that come up again and again in lab work and projects. It is meant for lab reports, student design projects and hobby builds such as Arduino work.

How the calculators work

• Everything runs in your browser. Nothing you type is stored or sent anywhere.
• Each result shows the formula used, so you can check how the number was reached.
• Unless stated otherwise, parts are assumed ideal. For a real design, check tolerances, temperature and ratings in the datasheet.
• Reference tables are generated with the same formulas as the calculators, so the tables and results always agree.

Standards and references

• Preferred resistor and capacitor values: IEC 60063 (E24 and E96 series)
• SMD resistor markings: the EIA-96 code
• PCB trace width: the current and temperature-rise relation in IPC-2221
• Wire sizes: the AWG definition, with copper resistivity of 1.724×10⁻⁸ Ω·m at 20 °C
• 555 timer: the astable equations from the NE555 datasheet

Report a problem or suggest a calculator

If a result looks wrong or you need a calculator that isn't here, write to sun031234@naver.com. Fixes come first, and the most requested calculators are added next.