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barcode reader in asp.net codeproject Part II in Software
Part II QR Code 2d Barcode Reader In None Using Barcode Control SDK for Software Control to generate, create, read, scan barcode image in Software applications. Painting Denso QR Bar Code In None Using Barcode drawer for Software Control to generate, create QRCode image in Software applications. Electronics
Read QR Code In None Using Barcode decoder for Software Control to read, scan read, scan image in Software applications. QR Code Maker In Visual C# Using Barcode creation for VS .NET Control to generate, create QRCode image in .NET applications. It is relatively simple to construct a DAC by taking advantage of the summing ampli er illustrated in 12 Consider the circuit shown in Figure 1524, where each bit in the word to be converted is represented by means of a 5V source and a switch When the switch is closed, the bit takes a value of 1 (5 V); when the switch is open, the bit has value 0 Thus, the output of the DAC is proportional to the word bn 1 bn 2 b1 b0 You will recall that a property of the summing ampli er is that the sum of the currents at the inverting node is zero, yielding the relationship va = RF bi 5 Ri i = 0, 1, , n 1 (1524) Draw Quick Response Code In Visual Studio .NET Using Barcode creation for ASP.NET Control to generate, create QR Code JIS X 0510 image in ASP.NET applications. QR Code Maker In .NET Using Barcode generator for .NET framework Control to generate, create QRCode image in .NET applications. RF Vin Rn 1 bn 1 Rn 2 bn 2 + va
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Drawing Barcode In None Using Barcode generation for Software Control to generate, create barcode image in Software applications. Printing EAN 13 In None Using Barcode printer for Software Control to generate, create EAN13 image in Software applications. where Ri is the resistor associated with each bit and bi is the decimal value of the ith bit (ie, b0 = 20 , b1 = 21 , and so on) It is easy to verify that if we select Ri = R0 2i (1525) Create Code 128 Code Set A In None Using Barcode encoder for Software Control to generate, create Code 128C image in Software applications. Draw Code39 In None Using Barcode generator for Software Control to generate, create Code 39 Full ASCII image in Software applications. R0 b0
Identcode Creator In None Using Barcode printer for Software Control to generate, create Identcode image in Software applications. Matrix 2D Barcode Generation In Visual Studio .NET Using Barcode generator for .NET framework Control to generate, create 2D Barcode image in VS .NET applications. Figure 1524 nbit digitaltoanalog converter (DAC) Make EAN13 In Java Using Barcode maker for Java Control to generate, create EAN13 image in Java applications. Bar Code Recognizer In Java Using Barcode reader for Java Control to read, scan read, scan image in Java applications. we can obtain weighted gains for each bit so that va = RF n 1 (2 bn 1 + + 21 b1 + 20 b0 ) Vin R0 (1526) Barcode Scanner In VS .NET Using Barcode Control SDK for ASP.NET Control to generate, create, read, scan barcode image in ASP.NET applications. UPC Code Reader In VS .NET Using Barcode recognizer for Visual Studio .NET Control to read, scan read, scan image in Visual Studio .NET applications. and so that the analog output voltage is proportional to the decimal representation of the binary word As an illustration, consider the case of a fourbit word; a reasonable choice for R0 might be R0 = 10 k , yielding a resistor network consisting of 10, 5, 25, and 125k resistors, as shown in Figure 1525 The largest decimal value of a fourbit word is 24 1 = 15, and so it is reasonable to divide this range into steps of 1 volt (ie, v = 1 V) Thus, the fullscale value of va is 15 V: 0 va 15 V and we select RF according to the following expression: RF = v R0 1 104 = =2k Vin 5 UPCA Supplement 2 Generator In VS .NET Using Barcode drawer for Reporting Service Control to generate, create UCC  12 image in Reporting Service applications. Barcode Generator In None Using Barcode creation for Font Control to generate, create barcode image in Font applications. 2 k 125 k b3 25 k 5 k b1 10 k b0 va + b2
4bit DAC with 015 V range
The corresponding fourbit DAC is shown in Figure 1525 The DAC transfer characteristic is such that the analog output voltage, va , has a steplike appearance, because of the discrete nature of the binary signal The coarseness of the staircase can be adjusted by selecting the number of bits in the binary representation The practical design of a DAC is generally not carried out in terms of discrete components, because of problems such as the accuracy required of the resistor value Many of the problems associated with this approach can be solved by designing the complete DAC circuit in integrated circuit (IC) form The speci cations stated by the IC manufacturer include the resolution, that is, the minimum nonzero voltage; the fullscale accuracy; the output range; the output settling time; the power supply requirements; and the power dissipation The following examples illustrate the use of integrated circuit DACs Figure 1525 Fourbit DAC
15
Electronic Instrumentation and Measurements
EXAMPLE 156 DAC Resolution
Problem
Determine the smallest step size, or resolution, of an 8bit DAC
Solution
Known Quantities: Maximum analog voltage Find: Resolution v Schematics, Diagrams, Circuits, and Given Data: va, max = 12 V Analysis: Using equation 1523, we compute: v = va, max va, min 12 0 = 8 = 471 mV 28 1 2 1
Comments: Note that the resolution is dependent not only on the number of bits, but also on the analog voltage range (12 V in this case) EXAMPLE 157 Determining the Required Number of Bits in a DAC
Problem
Find an expression for the required number of bits in a DAC using the de nitions of range and resolution Solution
Known Quantities: Range and resolution of DAC Voltage level corresponding to logic 1 Find: Number of DAC bits required Schematics, Diagrams, Circuits, and Given Data: Range: the analog voltage range of the DAC = va, max va, min Resolution: the minimum step size v Vin = voltage level corresponding to logic 1 0 V = voltage level corresponding to logic 0

