diff --git a/pcb_calculator/eserie_help.md b/pcb_calculator/eserie_help.md index 884f91daeb..357c8367a6 100644 --- a/pcb_calculator/eserie_help.md +++ b/pcb_calculator/eserie_help.md @@ -1,31 +1,25 @@ E-series defined in IEC 60063 are a widely accepted system of preferred numbers for electronic components. Available values are approximately -equally spaced in a logarithmic scale. Although E-series are used for -Zener diodes, inductors and other components, this calculator is mainly -intended for resistors. +equally spaced in a logarithmic scale. E12: 1,0 1,2 1,5 1,8 2,2 2,7 3,3 3,9 4,7 5,6 6,8 8,2 E6: 1,0 - 1,5 - 2,2 - 3,3 - 4,7 - 6,8 - E3: 1,0 - - - 2,2 - - - 4,7 - - - E1: 1,0 - - - - - - - - - - - -If your design requires any resistor value which is not readily available, -this calculator will find a combination of standard E-series components to -create it. You can enter the required resistance from 0,0025 to 4000 kOhm. -Solutions using 3 or 4 resistors are given if a better match can be found. -The 4R checkbox option will take longer to process is considered for the E12 -series only. Optionally it is possible to exclude up to two additional -values from the solution for the reason of being not available. If a -E-series value is entered to the required input field, it is always excluded -from any solution as it is assumed that this value is unavailable. + +This calculator finds combinations of standard E-series components to +create arbitrary values. You can enter the required resistance from 0,0025 to 4000 kOhm. +Solutions using up to 3 components are given. + +If a closer solutions is needed, the 4R checkbox option will give solutions +using 4 components for the E12 series only. This option +may take longer to compute. + +It is also possible to specify up to two values to exclude from the solution if these +component values are not available Solutions are given in the following formats: R1 + R2 +...+ Rn resistors in series R1 | R2 |...| Rn resistors in parallel R1 + (R2|R3)... any combination of the above -__Example:__ Voltage dividers, commonly used for 1:10 range selection -require resistor ratio values 1:9. Unfortunately the "9" is a value, what -is not even in the E192 series available. Deviation of 1% and more is yet -unacceptable for 8 bit accuracy. For a required resistor value of 9 kOhm, -the calculator suggests the E6 values 2k2 + 6k8 in series as a possible -exact solution.