If anyone needs a very useful voltage divider calculator, here’s one that searches through actual resistor values to find the best match for your Vin / Vout, then tells you what the min/max voltage will be based on the resistor tolerances. :-)
Voltage Divider Calculator
The Voltage divider tutorial is VERY helpful and straight forward. But as I plan to use one to divide 5 volts down to 3.3 as done in your example, I am concerned that my calculations do not include the resistance (impedance) of the device being connected across R2. In the case of the GPIO of a Raspberry Pi or in the accelerometer case, when I connect the input of this across R2, might if significantly change the effective resistance of R2 and thus the amount of voltage across it? How can I know the impedance of devices such as what I mentioned? Many thanks.
For most components that would most likely be listed in the data sheet. If it’s not then the worst case scenario is using a volt meter to measure the actual resistance.
Thanks for refreshing my knowledges.
Please write post about “Voltage doubling”.
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