# Electronics Formula Excel Cheat Sheet Project

#### FredM

Joined Dec 27, 2005
124
I needed to calculate the voltage on a capacitor after a given time, and also needed to calculate the time required to charge a capacitor to a given voltage.. maths being rusty (and losing my SC which had all the formulas programmed in ) I resorted to Excel.

The attached .xls (in .zip) may be of use to others.. it contains 2 simple routines..

1.) Given applied voltage, R, C, and time (t), it outputs the instantaneous voltage across the capacitor at t.

2.) Given applied voltage, R, C, and the voltage required across the capacitor, it outputs the time at which this voltage appears across the capacitor.

You will need the LN() function installed in Excel or (other spreadsheet)

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#### agentofdarkness

Joined Oct 9, 2007
42
If you have an RC circuit, you can solve the following differential equation:

EMF = Vr + Vc (Kirchoff's Voltage Rule)
Vr = IR = (dq/dt)*R
Vc = Q/C
EMF = (dq/dt)*R + (Q/C)

After solving the 1st order differential equation, you get
q = C(EMF)(1-e^(-t/(RC)))
i = dq/dt = (EMF/R)e^(-t/(RC))
This is for a DC circuit where the capacitor and resistor are in series.

#### Dave

Joined Nov 17, 2003
6,970
I needed to calculate the voltage on a capacitor after a given time, and also needed to calculate the time required to charge a capacitor to a given voltage.. maths being rusty (and losing my SC which had all the formulas programmed in ) I resorted to Excel.

The attached .xls (in .zip) may be of use to others.. it contains 2 simple routines..

1.) Given applied voltage, R, C, and time (t), it outputs the instantaneous voltage across the capacitor at t.

2.) Given applied voltage, R, C, and the voltage required across the capacitor, it outputs the time at which this voltage appears across the capacitor.

You will need the LN() function installed in Excel or (other spreadsheet)
This is a pretty good idea. I usually resort to the old pen and paper.

It might be an idea to run a small project that implements and graphs all of the major electronics formula and functions for people new to the subject. Perhaps this could be the spring board from which to build from.

I'd be interested in helping out.

Dave

#### FredM

Joined Dec 27, 2005
124
This is a pretty good idea. I usually resort to the old pen and paper.

It might be an idea to run a small project that implements and graphs all of the major electronics formula and functions for people new to the subject. Perhaps this could be the spring board from which to build from.

I'd be interested in helping out.

Dave
Hi Dave -

Non-linear stuff is where I have problems, which is why I resorted to Excel.. However, there is no reason why a single spreadsheet could not be produced which contains the major formulas - from ohms law up..

If a worksheet was done for each 'group', this could be quite an interactive project - and need not be limited to formulas.. Simple circuits (standard op-amp configurations, 555 timers etc) could be 'simulated' quite simply.

I attach an example, based on the computations of the last..
This is a spreadsheet to calculate frequency and M/S ratio of 555 timer acting as oscillator..

I cannot spend any more time on the above 'project' at the moment, but would be happy to participate in the new year.. I dont think much co-ordination is required though.. If peeps leave worksheets unprotected, and are free to use / modify what has been created, or create new sheets.. they could be pasted here and collated later.

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#### Distort10n

Joined Dec 25, 2006
429
Hello Dave,

This is a really good idea. Many engineers that I work with use Excel for everything. I have several Excel files myself showing how to calculate the input common mode range of single supply in-amp.

Maxim also has an application note called "Exact Circuit Analysis" which uses Excel to calculate the impedance of an RC circuit. It then uses it to calculate the phase shift in the open loop curve of an op-amp.

I think this would be a great project for things like Ohm's law, Power, Reactance, transistor curves, etc.

#### Dave

Joined Nov 17, 2003
6,970
Hi FredM and knightofsolamnus,

I'm glad we think this may be a good idea; to honest I'm surprised we haven't embarked on something like this before. I am willing to act as a coordinator, unless someone has the desire to take charge.

FredM's spreadsheet is a good starting point. knightofsolamnus, if you want to upload your spreadsheets, I can merge them with FredM's and a couple of working spreadsheets I have and we can get the ball rolling. I can then post up a first version covering the basics.

If FredM is happy for me to do so, I will change the thread name to something that better reflects the objectives of the project and I will stick it to the top of the Electronics Resources forum.

If anyone else wishes to get involved please post and get involved.

Dave

#### FredM

Joined Dec 27, 2005
124
If FredM is happy for me to do so, I will change the thread name to something that better reflects the objectives of the project and I will stick it to the top of the Electronics Resources forum.
Dave
I am more than happy with this..

#### Dave

Joined Nov 17, 2003
6,970
I am more than happy with this..
Done. I'll get grafting on some basics. If anyone has any formula that would be good for putting into this, please let me know.

I hope we can have a good working version in the new year.

Dave

#### Distort10n

Joined Dec 25, 2006
429
Here is an Ohm's Law calculator. I was going to use VB scripts in Excel (bought a book to learn how to do it) but just relied on simple Excel formulas for now.

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#### Dave

Joined Nov 17, 2003
6,970
Here is an Ohm's Law calculator. I was going to use VB scripts in Excel (bought a book to learn how to do it) but just relied on simple Excel formulas for now.
Hi knightofsolamnus,

Good starting point and it looks quite snazzy with the colours and chart in the middle.

I did consider the options of using VB macros, and even the idea of doing it in C++, however this is intended to be a simple calculator type application for general use. Why spend time implementing features that are readily available in Excel (I'm sure we will hit a stumbling block at some point when a bit of VB code will be needed).

I encourage anyone else who has Excel worksheets for calculating values in just about any electronics applications to submit it - it would be great to have a collective effort covering a wide range of formulas.

Dave

#### FredM

Joined Dec 27, 2005
124
Hi Dave, - What is required most for this 'collection' ? - I have some time now and am looking at doing some sheets, but do not wish to waste time on stuff which may have been submitted allready.. Has everything which has been submitted so far been posted here? I was looking at the "cheat sheet" on the 'general' forum, and thinking that this could easily be converted to Excel..
Regards,
Fred.

#### Dave

Joined Nov 17, 2003
6,970
Hi Dave, - What is required most for this 'collection' ? - I have some time now and am looking at doing some sheets, but do not wish to waste time on stuff which may have been submitted allready.. Has everything which has been submitted so far been posted here? I was looking at the "cheat sheet" on the 'general' forum, and thinking that this could easily be converted to Excel..
Regards,
Fred.
Hi Fred,

I am currently building on knightofsolamnus' great starting Excel sheet. At the moment I am adding capacitor and inductor equations to your part in the OP and I have added a Star-Delta calculator. I will also be adding a few more equations from Volume II. At this point I will send it back to knightofsolamnus who has agreed to format the spreadsheet to make it look good (just have a look at how good his Ohm's Law calculator looks).

If you want to look at m4yh3m's Cheat Sheet and convert some of the formulas to an Excel calculator then feel free to do so; the part on Ohm's Law and Power has been covered.

I will be forwarding some of the work I have done to knightofsolamnus this weekend and he can post up the formatted version later to allow us to verify the formulas are correct.

As this is an ongoing piece of work it will take several versions to get a suitable amount of formulas in there and iron out any mistakes and errors.

Dave

#### arrie

Joined Jun 27, 2008
6
Hi Dave,
just wondering,

#### m4yh3m

Joined Apr 28, 2004
186
when this project is completed, would it be an issue to tack it on under my cheat sheet attatchments? proper credits will be given, of course. unless the mods want to generate a new (and aptly named) thread which will contain all of files -- or generate something like files.allaboutcircuits.com with a more organized layout for non-schematic/data files like these "User submitted tools for assistance in the field of electronics". I like it.

Any ideas about the general layout of the formulas? I've had some experience with a nifty custom accounting spreadsheets that could come in handy for the organization/layout and variables setup. It was used for a restaurant, but the number storage in relation to the many calculations for cash in/cash out/tax/cost would help greatly for creating an "input 2 numbers, generate everything else" setup.

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#### Dave

Joined Nov 17, 2003
6,970
Hi all,

Firstly, I'd like to extend my apologies to this project, I picked up the can for this and then work needs kicked in which took my attention away. As a result, it fell on the back-burner and I haven't progressed it much from the half-baked structure I kicked it off with. I did speak with D1stortion about formatting some of my work as per his Ohm's Law calculator.

m4yh3m, if you are interested in taking part any role of nifty customisation then let me know via PM. Getting these calculators into a quasi-usable state might be useful, if only for the basic equations. I can crunch the formulas, and weed out the appropriate equations, but design and usability is not my forte.

If not, I may do this with the open source ethic - put up a few unformatted spreadsheet and see if someone picks it up and improves on it.

Btw, I like the files.allaboutcircuits.com idea, I'll float that one by Rob.

Dave

#### jackgopher

Joined Dec 7, 2008
1

___________
Formulas Excel

#### rick5

Joined Jul 17, 2008
12
This is quite a worthwhile thing to do I think.

A while ago I was looking at the various well known Mathematical s/w packages and thinking may be I should obtain one of them for circuit calcutions, in addition to using a SPICE package. Then I though, that would be overkill and not necessary.

I think the spreadsheet should have the standard pn junction diode equation in it, that would be handy.

#### Surg

Joined Jan 7, 2009
16
Still looking for it. Thanks to all who contributed..

#### Jeff Gillmet

Joined Mar 20, 2009
1
I have an Ohm's Law Excel I've put together, over the last few years, specifically formatted for my Palm. Some tabs are for calculations specific to my work (Air Traffic Control Maintenance). Enjoy

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