Difference between revisions of "Electronics Formulas"
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1 over 2πRC | 1 over 2πRC | ||
| − | If you know your resistor (i.e. use a standard value, say 10k, 100k) you can reverse calculate the desired capacitance easily. Some of these values can be more or less memorized if you do this enough, given that a 2πR with R being a factor of 10 will always be 2π to some decimal point. That leaves the capacitance as the only variable. | + | If you know your resistor (i.e. use a standard value, say 10k, 100k) you can reverse calculate the desired capacitance easily. Some of these values can be more or less memorized if you do this enough, given that a 2πR with R being a factor of 10 will always be 2π to some decimal point. That leaves the capacitance as the only variable. Note this is for the 3db point, or about 70%, and you would might make this 2 * desired frequency per AoE, Student manual. |
[[File:Formula for high or low pass filter.png|||]] | [[File:Formula for high or low pass filter.png|||]] | ||
Revision as of 02:22, 16 February 2025
I'm going to try to keep some useful (but still practical) formulas for electronics here. The goal will not be to have a million formulas, but to have the formulas that are useful, and not so complex that you would rather use an online or spreadsheet calculator for them.
List
Todo: enable math extension.
High or Low Pass Filter
1 over 2πRC
If you know your resistor (i.e. use a standard value, say 10k, 100k) you can reverse calculate the desired capacitance easily. Some of these values can be more or less memorized if you do this enough, given that a 2πR with R being a factor of 10 will always be 2π to some decimal point. That leaves the capacitance as the only variable. Note this is for the 3db point, or about 70%, and you would might make this 2 * desired frequency per AoE, Student manual.
THD from an Oscilloscope FFT function
To recap, in this video he has a DUT that he is checking how it changes the input from a function gen, by outputting to the FFT mode of the scope, counting the dBc between the first fundamental and each following harmonic, and then doing some math to calculate the result. He also compares the result to test equipment that has a THD mode. If you have a scope w/FFT and a DUT that you need to check the THD of (and the noise is simple enough) this video may help. Note that this is usable for fairly large THD values (though a dedicated THD analyzer, or spectrum analyzer may do better, that is left open to discussion).
