Electronics Calculator
Read a resistor's color bands or SMD code and a capacitor's code, apply Ohm's law, size an LED's resistor or a voltage divider, add parts in series or parallel
Bands
Three digits (472), four (4702), with R for the decimal point (4R7, R010), or EIA-96: two digits and a letter (01C).
Any two values
Resistor
| Standard value | Current | Power in the resistor | Rating |
|---|
The nearest standard values above the exact one, so the current stays at or below the one asked. The rating leaves the resistor twice the power it takes. Forward voltages are typical: your LED’s datasheet gives its own.
Output voltage
Vout = Vin × R2 / (R1 + R2). A load across R2 sits in parallel with it and pulls the output down.
Find R1 and R2
| R1 | R2 | Output | Error | Current |
|---|
A larger total draws less current, but a load then pulls the output further down.
Separated by commas, spaces or lines.
Three digits in picofarads, the third the number of zeros (104 = 10 × 10⁴ pF), then the tolerance letter; a voltage code before (2A = 100 V). Or a value with a letter for the point: 4n7, 2u2.