associated with line voltage (60 Hz) would be filtered out but a signal of 25 Hz would be allowed to pass.
Also, in a digital circuit, a low pass filter is often used to filter an input from a switch.
Figure 6-5. Low pass Filter
A low pass filter may be constructed from one resistor (R) and one capacitor (C). The cut off frequency is determined according to the formula:
Fc = | 1 | R = | 1 |
2*Pi*R*C2*Pi*C*Fc
6.6 A/D RESOLUTION & ENGINEERING UNITS
Resolution is specified in bits, such as 8, 10 or 12 bits. The 12 bits are really a power of 2 indicating the number of divisions of full scale the converter can resolve. For example, a 12 bit converter can resolve (212) = 4096 divisions of full scale. If the input of the board were +/- 5 volts full scale, each of the 4095 steps would be equal to 0.00244 volts.
Reading from the A/D converter would be thus:
Converter # | Volts |
4095 | 4.9976 |
4094 | 4.9951 |
4093 | 4.9927 |
2048 | 0.0 |
1 | − 4.9976 |
0 | − 5.0 |
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