Pot tapering resistors spreadsheet with graph

[Phoenix]

Hi everyone.

Reading through some of the old posts here, I've seen the question asked many times about tapering resistors, as inspired by RG's wonderful resource The Secret Life of Pots. But it seems that people often struggle to put that information to practical use.
One error I've seen stated often is that a resistor placed across a linear pot terminals 1 and 3 will give it a log or anti-log response, when in fact it won't alter the taper at all, only the total resistance of the pot, as per the parallel resistor calculation. To alter the taper of a pot, resistors must be placed across terminals 1 and 2, 2 and 3, or both.

I thought it might help to have an interactive, visual representation of pot tapers, and their interaction with tapering resistors.

The graph will display a selectable "example" taper, for comparison with your results. It also displays the voltage division ratio and the changing total resistance.

All common values of pots are available from a drop down menu, and E24 values are available for the parallel/tapering resistors.

The minimum and maximum value of the resulting pot are also displayed.

All values are selected via drop-down menus to ensure consistent results, and cells are protected as much as possible, although can still be messed up if you're not careful.

The format is Open Office Calc, a free office suite available here.
No guarantees that it will work correctly if imported into another office suite.

I hope that it's error free, but I haven't tested all possible combinations, so please let me know if you find any bugs.

Here's a link to the file for download: Pot tapers.ods

I hope that some of you may find it useful.

[MaxPower]

That's cool. I'll give it a try.

Thanks.

[Phoenix]

I've just added another feature to the spreadsheet - you can now enter the source impedance of the driving stage to see the effect it has on the voltage divider curve. For high source impedances like common emitter gain stages, this can be significant, and drastically alter the curve for initially calculated results. Op amp stages by comparison will have relatively low output impedances and so will not significantly alter the response.

Here are some examples of that feature:



The original link should continue to work for the updated version, but here it is again anyway:
Pot tapers.ods

[Phoenix]

Just wondering if anyone had given this a try and what they thought of it? If they found it useful? Any bugs? Any suggestions? Any other feedback?

Thanks.

[GGBB]

I'm just seeing this now for the first time. Looks awesome. I've wanted something like this as i always end up manually entering values into a spreadsheet to graph them.

[jatalahd]

Haven't tried it but looks very useful! This also gave me a flashback from last year. I remember that our forum member Brisance had a web-app that did something similar:

http://www.diystompboxes.com/smfforum/index.php?topic=111585

But unfortunately the link provided in that thread is not working anymore. Good to have a new tool for taper modeling.

[GGBB]

Any chance for an actual Excel version? When I try to open this in Excel 2010, first I get a warning about unreadable content which it asks me do I want to recover, then after I click yes it says it cannot be opened because it has been protected with a password.

[Phoenix]

Any chance for an actual Excel version? When I try to open this in Excel 2010, first I get a warning about unreadable content which it asks me do I want to recover, then after I click yes it says it cannot be opened because it has been protected with a password.

I don't own a copy of Microsoft Office (haven't in years), so an actual Excel version isn't going to happen. However, I've started working on a Google Docs version so that people don't need to install software that they might not have. Hopefully that will make it easier for people to use.
Once I've got it finished I'll post a link.

Now for a quick rant:
That's bizarre that Excel can't import a different spreadsheet format because it's password protected - spreadsheet passwords do not encrypt the document or provide any real level of security, they merely prevent careless edits. It's simple enough to remove password restrictions on any format of spreadsheet using a simple text editor if you know what to look for.

[Jay]

I don't get a password message from Excel (2013 version), it just says the file is corrupt.

[Phoenix]

Ok, I think I've got it working in Google Sheets.
I've not used this method before, so I hope it works correctly. Please let me know if anyone has any trouble.
Theoretically, you should be able to save a copy to your own Google Docs, and you should be able to change the editable values, but other content should be protected.
I hope this works and is easier for people to access.

EDIT: Doesn't work, sorry, let me try again.
EDIT II: Got it working!

[GGBB]

I don't own a copy of Microsoft Office (haven't in years), so an actual Excel version isn't going to happen. However, I've started working on a Google Docs version so that people don't need to install software that they might not have. Hopefully that will make it easier for people to use.
Once I've got it finished I'll post a link.

Your copy of Open Office Calc doesn't let you save/export as Excel? Now that's bizarre.

Thanks for the Sheet version though - I downloaded that as Excel and it works fine. Looks nice so far.

[Phoenix]

Your copy of Open Office Calc doesn't let you save/export as Excel? Now that's bizarre.

I wouldn't have been surprised if it hadn't been compatible for whatever reason, just that throwing up its arms about a password seems like the least of its worries!
Because I don't have a copy of MS Office, I was reluctant to try exporting, as I had no way to test. Most probably would have ended up with something that didn't work with either Open Office or MS Office.

Thanks for the Sheet version though - I downloaded that as Excel and it works fine. Looks nice so far.

Glad it worked! Thanks for letting me know. Hope you find it useful.

[duck_arse]

I hadda quick look at it in openoffice the other day, no probs. a-popular-search-enginedocs, however, is a nightmare everytime for me. they don't like opera on linux.
[/some_arse_complaining]