Snubber Calculator

[valve5425]

After reading Jim Hagerman's paper, "Calculating Optimum Snubbers" and working my way through the formulae several times, I figured it would be easier to put it all on a spreadsheet rather than getting the calculator out every time! I haven't been able to find anything suitable on the web so I put this together.

I've checked it with his figures and it looks accurate but perhaps someone with a more mathematical brain than me could confirm the accuracy. Also, I did the spreadsheet originally in Libre Office .ods format so the conversion to .xlsx is OK but isn't protected and the layout is slightly off. Not a major problem but feel free to tinker with it and format it properly for Windows.

Attached are links to the spreadsheets, the original article plus an alternative method of calculating resonant frequency.

Hope you find these useful and any constructive feedback is welcome.

http://dl.dropbox.com/u/109520947/SnubberCalc.ods

http://dl.dropbox.com/u/109520947/SnubberCalc.xlsx

http://www.hagtech.com/pdf/snubber.pdf

http://www.syscompdesign.com/AppNote...ar-pickups.pdf


Above calculators now updated to include drop down lists to enable data to be entered in different units. Also, .xls file added below for older versions of Excel.

http://dl.dropbox.com/u/109520947/SnubberCalc.xls

[xstreme]

So at first sight appears to be sufficient...

[Pano]

Thanks very much for doing this! As xstreme says, it seems right at first glance. Will need to double check. Nice work on the spreadsheet and the formulas.

I was having fun modifying the XLS version to allow input directly in mH, pF and KHz, with the results in ohms, µF and pF for my own ease of use. All was going well until I tried to get the interwinding C to display in nF. Ooops, something went pair shaped. Will try again.

[valve5425]

Originally Posted by Pano

Thanks very much for doing this! As xstreme says, it seems right at first glance. Will need to double check. Nice work on the spreadsheet and the formulas.

I was having fun modifying the XLS version to allow input directly in mH, pF and KHz, with the results in ohms, µF and pF for my own ease of use. All was going well until I tried to get the interwinding C to display in nF. Ooops, something went pair shaped. Will try again.

Glad it's of use. You should be able to enter values in scientific notation so 25nf would be 25e-08 Farads, 25pf would be 25e-011 Farads, etc.

Use something like this;

Electronics 2000 | Capacitance Unit Converter

Might make things easier and you could also cut and paste the result from the spreadsheet into the capacitance calculator.

[valve5425]

Just had a thought!! If I get the time I'll look at trying to incorporate a converter into the spreadsheet. Even better would be to make it possible to enter any value, but that would take a bit more working out.

[Pano]

It's not hard to do. I had it working well until I tried to fix the last cell. I'll post what I have, when I fix my mistake.

[Bill_P]

I believe there is an error in the Rs power calculation. The secondary RMS voltage term should be squared in the formula.

[valve5425]

Originally Posted by Pano

It's not hard to do. I had it working well until I tried to fix the last cell. I'll post what I have, when I fix my mistake.

Nice one! It's a bit late in the day here to be doing complicated stuff.

[valve5425]

Originally Posted by Bill_P

I believe there is an error in the Rs power calculation. The secondary RMS voltage term should be squared in the formula.

Thanks for that. I'll check it out tomorrow.

[xstreme]

Originally Posted by valve5425

Glad it's of use. .

has nothing to do but it is interesting


eEngineer - Electrical Engineering, EMI/EMC, RFI