Handy Gadgets and Resistor Divider Calculations

RE: Handy Gadgets and Resistor Divider Calculations

Bruce Trump — Fri, 31 May 2013 13:13:17 GMT

Sounds useful, Percy. Note that the Excel sheet provided above has cells that calculate the nearest 1% (R96) resistor value. For example, cell M8 calculates the nearest standard 1% resistor for the value of cell F7. The formula in M8 can be easily copied and used for the types of calculations you've done. -- Bruce

RE: Handy Gadgets and Resistor Divider Calculations

Percy Williams — Fri, 31 May 2013 12:09:14 GMT

This is very simple:This is for a potential divider where only preferred values can be used. I did an Excel spreadsheet where cells in the first row were populated with preferred resistor values. Cells in the first column were likewise populated. The other cells had a formula in for calculating the division ratio from these resistors. It was then an easy matter to scan the table and find the combination that gave the best result required. I did a similar one for series combinations and for parallel combinations.

RE: Handy Gadgets and Resistor Divider Calculations

Eric Fletcher — Sun, 26 May 2013 15:06:54 GMT

55 years ago, when a junior engineering student I was using my slide rule inherited from my grand-father (an artillery officer !) to

compute R/2R , R/10R, Pi/Ratio of Pi, etc...networks ...........Sorry, it took me 20 years to get a TI handheld calculator to execute the

same computations,! By the way, I was so good, that I executed 60% of the computations by head ( and still to day !!! )

RE: Handy Gadgets and Resistor Divider Calculations

Bruce Trump — Sat, 18 May 2013 03:44:07 GMT

Bravo, Alan. You're a serious gadget man! -- Bruce

RE: Handy Gadgets and Resistor Divider Calculations

Alan Campbell — Sat, 18 May 2013 03:23:27 GMT

When it comes to Excel, I'm working my way through creating a series of spreadsheets. I'm getting my head around I & Q demodulation, along with DSP.

I've started with a series of sinewaves, assorted magnitudes, rounded as 14-bit integers. 4096 samples along with a FFT (and windowed FFT!) makes a big spreadsheet.

My second sheet takes the samples from the 1st, splits into I & Q, and has a very basic FIR. FFT results too!

Third spreadheet [in progress]: Hilbert transform!

Final spreadsheet: Sum and difference of I & transformed Q: hopefully showing upper vs lower sidebands of original mix of sinewaves...