Useful calculations for electronics engineers - Page 1
Forum section: electronics / projects

author: lgbeno
author_rank: Frequent Contributor
timestamp: July 24, 2013, 11:58:06 am
content: I wanted to ask everyone what are some calculations that you do frequently in engineering? Some of my ideas:Convert frequency to time periodExample type in "1MHz," get out 1usCalculate a voltage divider with standard resistor valuesCreate a 1pole low pass filter & calculate the corner freq and attenuation at a specifis frequency (using standard component values)Hex to dec and dec to hex conversionCascadded noise figure of a rf front endCalculate battery life based on a amp hour capacity, current drain & duty cycle.Power dissipation and total efficenty for a power management designI don't do it often but have seen handy online calculators for rf impedance matching networksPcb calculations like mils to mm, trace impedance, max trace currentThermal calculations for temp rise with give pdiss and thetaJConver db of gain to linear scale and linear to dbDbm to mW

author: darrylp
author_rank: Regular Contributor
timestamp: July 24, 2013, 12:18:41 pm
content: Basically anything already in the android app Electrodroid.Not sure if iOS has a port of it.--Darryl

author: ptricks
author_rank: Frequent Contributor
timestamp: July 24, 2013, 12:33:31 pm
content: I do a lot of RF stuff so I am always calculating inductance and how many turns of wire I need on a torroid.http://coil32.narod.ru/index-en.html

author: fpliuzzi
author_rank: Regular Contributor
timestamp: July 24, 2013, 11:25:42 pm
content: Besides the already mentioned Electrodroid, another handy Android app is the ELEKTOR RF & Microwave Toolbox. The Google Play link includes a list of the 55 tools included in this app.https://play.google.com/store/apps/details?id=mwave.mwcalculator_pro&hl=enRegards,Frank

author: smashedProton
author_rank: Frequent Contributor
timestamp: July 25, 2013, 12:10:20 am
content: Speaking of RF, what are some good online resources for me to get some knowledge on it?

author: Psi
author_rank: Super Contributor
timestamp: July 25, 2013, 12:20:56 am
content: Needed when building transformerless mains power supplies.Xc (capacitive reactance) = 1 / (2 * pi * F * C)or, if you prefer, Xc = 1 / (Tau * F * C)

author: c4757p
author_rank: Super Contributor
timestamp: July 25, 2013, 01:05:17 am
content: Quote from: Psi on July 25, 2013, 12:20:56 am+1

author: Smokey
author_rank: Super Contributor
timestamp: July 25, 2013, 01:12:01 am
content: The internet is a wonderful thing. Here are some of my links....Convert frequency to time periodhttp://www.calctool.org/CALC/other/converters/freqCalculate a voltage divider with standard resistor valueshttp://www.raltron.com/cust/tools/voltage_divider.aspCreate a 1pole low pass filter & calculate the corner freq and attenuation at a specifis frequency (using standard component values)http://sim.okawa-denshi.jp/en/CRlowkeisan.htmHex to dec and dec to hex conversionGoogle "0x41A45B4 in decimal"Cascadded noise figure of a rf front endRF = black magic. I don't mess with black magic.Pcb calculations like mils to mm, trace impedance, max trace currentC4 Current Carrying Capacity Calculator From Black Stick

author: c4757p
author_rank: Super Contributor
timestamp: July 25, 2013, 01:17:30 am
content: Some of these are just so unnecessary. Frequency to time period??Quote from: Smokey on July 25, 2013, 01:12:01 amStandard resistor values? What am I missing? Seems to just be a dumb solver of Vout = Vin R2/(R2+R1)...The filter calculators are very nice.

author: ptricks
author_rank: Frequent Contributor
timestamp: July 25, 2013, 01:53:00 pm
content: Another torroid calculator for RF, might be easier than other one since it uses torroid colors.http://www.dl5swb.de/html/mini_ring_core_calculator.htm

author: KJDS
author_rank: Super Contributor
timestamp: July 25, 2013, 02:27:04 pm
content: There's a lot of RF stuff herehttp://www.rfcafe.com/references/electrical.htmI've got almost everything I ever need in spreadsheets, from almost any form of practical RF filter to complex broadband smith chart matching. Saves me having to work through the equations again.

author: free_electron
author_rank: Super Contributor
timestamp: July 25, 2013, 05:25:21 pm
content: 1+1 ?

author: KJDS
author_rank: Super Contributor
timestamp: July 25, 2013, 05:51:57 pm
content: Quote from: free_electron on July 25, 2013, 05:25:21 pmThat's a question to ask an accountant.

author: Neilm
author_rank: Super Contributor
timestamp: July 25, 2013, 06:43:29 pm
content: Quote from: KJDS on July 25, 2013, 05:51:57 pmOnly if you need the answer to be 3. (Or as an accountant I know would say "what do you want it to be?"

author: free_electron
author_rank: Super Contributor
timestamp: July 25, 2013, 06:59:34 pm
content: the answer could have been 1.999999999998 if it was run on the defective pentium ... i'd like a shortcut button that tests for this. call it an integrity check.

author: Conrad Hoffman
author_rank: Super Contributor
timestamp: August 03, 2013, 05:14:26 am
content: I have some oddball stuff on this sheet that you'd be hard pressed to find on the 'net anywhere.http://www.conradhoffman.com/handyform1.doc

author: westfw
author_rank: Super Contributor
timestamp: August 03, 2013, 06:49:59 am
content: I always found the "simple equations" that get taught to (for example) radio amateurs to be really annoying. "The half-wave dipole length (in feet) is given by 468/f, where f is the frequency in MHz." Grr. (This is the kind of stuff you're supposed to memorize to get your radio license, BTW.)Give me real equations with named constants that have Units, dammit.That said, T=RC, where T is the time constant in seconds, R is in megohms and C is in microfarads.This is really obvious, but matches up nicely with common real components for long duration timer circuits.

author: Bored@Work
author_rank: Super Contributor
timestamp: August 03, 2013, 07:12:24 am
content: Quote from: westfw on August 03, 2013, 06:49:59 amOh dear. T, R and C need not to be in any specific unit, only in properly defined units of resistance (for the R) and capacitance (for the C) as input. With that you get your T in any properly defined unit of time in which you like to have it. If you want, you can have it in tropical years, or whatever unit you can come up with.All you need to do it to get your math right. The same old thing discussed a thousand times here. Get your math right also applies to calculating the units, not just the values.

author: Psi
author_rank: Super Contributor
timestamp: August 04, 2013, 12:49:32 pm
content: Yeah i usehttp://sim.okawa-denshi.jp/en/CRlowkeisan.htmquite often.Very useful.

author: lgbeno
author_rank: Frequent Contributor
timestamp: August 04, 2013, 02:23:21 pm
content: Thanks for all if the suggestions guys!Any other things that you would like to calculate but haven't found a suitable resource yet?Sent from my iPhone using Tapatalk 2