PCB Design Glossary


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E

E-series

Inductors, Resistors, Capacitors, etc... have standard values based largely on the equation

E Series Approximation

where m is an E-Series value m=3\times2^x\;x\in {1,2,3,4,5,6}={6,12,24,48,96,192} and n is a positive integer less than m.

Each order-of-magnitude is logarithmically broken into a set number of values.  For E24 series, those values are 1.0, 1.1, 1.2, 1.3, 1.5, 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.9, 3.2, 3.5, 3.8, 4.2, 4.6, 5.1, 5.6, 6.2, 6.8, 7.5, 8.3, 9.1

\sqrt[24]{10^0}=1.0 \sqrt[24]{10^1}\approx 1.1 \sqrt[24]{10^2}\approx 1.2 \sqrt[24]{10^3}\approx 1.3 \sqrt[24]{10^4}\approx 1.5 \sqrt[25]{10^5}\approx 1.6
\sqrt[25]{10^6}\approx 1.8 \sqrt[25]{10^7}\approx 2.0
1.0 Ω
1.1 Ω 1.2 Ω 1.3 Ω 1.5 Ω 1.6 Ω 1.8 Ω 2.0 Ω
10 Ω 11 Ω 12 Ω 13 Ω 15 Ω 16 Ω 18 Ω 20 Ω
100 Ω 110 Ω 120 Ω 130 Ω 150 Ω 160 Ω 180 Ω 200 Ω
1 kΩ 1.1 kΩ 1.2 kΩ 1.3 kΩ 1.5 kΩ 1.6 Ω 1.8 Ω 2 kΩ

\sqrt[24]{10^8}=2.2 \sqrt[24]{10^9}\approx 2.4 \sqrt[24]{10^10}\approx 2.6\\ \Rightarrow2.7 \sqrt[24]{10^11}\approx 2.9\\ \Rightarrow3.0 \sqrt[24]{10^12}\approx 3.2\\ \Rightarrow 3.3 \sqrt[25]{10^13}\approx 3.5\\ \Rightarrow3.6
\sqrt[25]{10^14}\approx 3.8\\ \Rightarrow3.9 \sqrt[25]{10^15}\approx 4.3
2.2 Ω 2.4 Ω 2.7 Ω 3.0 Ω 3.3 Ω 3.6 Ω 3.9 Ω 4.3 Ω
22 Ω 24 Ω 27 Ω 30 Ω 33 Ω 36 Ω 39 Ω 43 Ω
220 Ω 240 Ω 270 Ω 30 Ω 330 Ω 360 Ω 390 Ω 430 Ω
2.2 kΩ 2.4 kΩ 2.7 kΩ 3.0 kΩ 3.3 kΩ 3.6 kΩ 3.9 kΩ 4.3 kΩ

\sqrt[24]{10^16}=4.6\\ \Rightarrow 4.7 \sqrt[24]{10^17}\approx 5.1 \sqrt[24]{10^18}\approx 5.6 \sqrt[24]{10^19}\approx 6.2 \sqrt[24]{10^20}\approx 6.8 \sqrt[25]{10^21}\approx 7.5
\sqrt[25]{10^22}\approx 8.3\\ \Rightarrow 8.2 \sqrt[25]{10^23}\approx 9.1
4.7 Ω 5.1 Ω 5.6 Ω 6.2 Ω 6.8 Ω 7.5 Ω 8.2 Ω 9.1 Ω
47 Ω 51 Ω 56 Ω 62 Ω 68 Ω 75 Ω 82 Ω  91 Ω 
470 Ω 510 Ω 560 Ω 620 Ω 680 Ω 750 Ω 820 Ω 910 Ω
4.7 kΩ  5.1 kΩ 5.6 kΩ 6.2 kΩ 6.8 kΩ 7.5 kΩ 8.2 kΩ 9.1 kΩ

and the series would repeat for each multiple of 10 up into the MΩ range.

See https://en.wikipedia.org/wiki/E_series_of_preferred_numbers for more information


Eutectic

Pure substances undergo phase changes at specific temperatures.  Mixtures undergo phase changes over a range of temperatures.  At a specific ratio of substances, the solidus and liquids temperatures intersect at the Eutectic point.  At this point, the substance transitions directly from solid to liquid and back without entering an intermediate phase.

Phase Diagram

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