Showing posts with label dac. Show all posts
Showing posts with label dac. Show all posts

Monday, November 25, 2013

Basically the DAC circuit

Basically the DAC circuit is made to meet the need for the level of influence in the development of digital electronic circuits electronics world.
Since the discovery of Silicon and Germanium semiconductor material then quickly there was a revolution in terms of simplicity and accuracy of an electronic circuit. Besides, with the implementation of digital circuits will support at all in terms of data storage and mobility. Lots of data can now be operated with a computer is a data converted from analog signals. For example a voice signal or analog form of video can be played and stored using a computer after analog signals are converted into digital data.

Basically the DAC circuit
Advantages possessed by the digital data than analog signal is a certainty the nature of the data or logic. Digital data only can be divided into two kinds of logic high "1" and logic low "0". Logic 1 represents 5 volts and low logic voltage 0 volts represents. Examples of the advantages of digital signals over analog signals is on television or digital radio receiver. By implementing a digital system signals emitted by television or radio stations will form the data 1 and 0, so at the time of the transmission or delivery of data signals that change or damaged by the interruption of transmission will hardly change the logic of the signals. But if the transmitted signal is the original signal in the form of an analog signal then if just a little damage due to interruption of transmission, the signal to be received is a signal that has been damaged serve targeted.

In the DAC circuit above uses two LM741 Op-Amp IC is often used as an amplifier. IC1 to function as a producer of analog signal is reversed, and turned back IC2 function signal from IC1. Basic circuit of the DAC is a common amplifier circuit, only used a variation of several resistors in order to obtain a regular reinforcement signal. Rules that must be understood from this DAC circuit is the value of resistors on the input op-amp. The value for the resistor at high bit (R4) should be 2x the amplifier resistor (R5), then for the next bit should be 2x the resistor value at a higher bit. So if the circuit uses 4-bit DAC is the unit bit (lowest bit) is the value of bits to be 8x-4. From the picture above the unit bit is represented by resistor 80 Kohm.

Sample Conditions:
- 0001 (1) = switch SW1 closed and others opened, the voltage output produced is (5K/80K) x 9 volt = 0.5625 volts
- 0010 (2) = SW2 is closed and another switch is opened, the output voltage is (5K/40K) x 9 volts = 1.125 volts
- 0011 (3) = SW1 and SW2 is closed and another switch is opened, the voltage output is (5K/Rparalel 80K and 40K) x 9 volt = (5K/26, 667K) X 9 volt = 1.6875 volts
- 1000 (8) = SW4 is closed and another switch is opened, the output voltage is (5K/10K) x 9 volts = 4.5 volts.

From the above calculation can be concluded that unlicensed with a voltage output proportional to the input conditions, eg for 1 decimal is 0.5625 volts then, decimal 2 = 2 x 0.5625 = 1125 volts, decimal 3 = 3 x 0.5625 = 1.6875 volts, and so on. This condition is due to the parallel relationship between the input resistors.
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Tuesday, October 22, 2013

DAC with MCS5 Microcontroller

DAC With MCS5 Microcontroller
The figure below shows the Configuration DAC With artificial MCS51 Microcontroller National Semiconductor, capacitors C1, C2 and form a series of 12 MHz XTAL oscillator, capacitor C3 and resistor R1 form a series reset.


Digital scale is given to the B1 to B7 (leg 5 to 12) in the IC DAC0800, the binary value of the digital scale was converted into an analog magnitude of the current at IOUT (ft 4 DAC0800) and IOUT * (feet 2 DAC0800), then by IC Operational Amplifier LM741 flow is converted into voltage. The resulting voltage expressed by the formula shown in Figure below, in addition to depending on a digital scale weight value is given, this voltage depends on the size of Vref (DAC0800 14 feet).

DAC With MCS5 Microcontroller
figure.1 DAC With MCS5 Microcontroller

C3 is mounted on leg 16 and ground is useful for stabilizing the voltage generated. DAC0800 and LM741 using voltage source +12 Volt and -12 Volt, is somewhat different from the voltage that is usually used for digital circuits, so that digital signals can be received well IC DAC0800, DAC0800 equipped foot VLC (pin 1) for various voltage levels menyesesuaikan types of digital ICs. In the DAC0800 data sheet are shown in various series to be installed on this leg for DAC0800 can be used for a variety of digital IC family. In the circuit of Figure above, the DAC0800 is connected to the microcontroller MCS51 family who work at TTL voltage levels, for this purpose VLC leg connected to ground.

Behind the legs of the IC DAC0800 B1 through B8 are not equipped to accommodate a latch that is fed a digital scale, changing the combination of digital signals on the legs is a direct result of output voltage change. Construction inputs such DAC0800, DAC0800 result can not be connected directly to a channel-data (data bus) microprocessor system, the relationship DAC0800 to the processor must pass through the parallel port.

In Figure 1, the DAC0800 is connected to the parallel port P1 from AT89Cx051. Connecting the DAC0800 to the other MCS51 family, for example AT89C51, can pass parelel ports P0, P1, P2 or P3, depending on the conditions established series. Instructions to remove the voltage in the circuit of Figure 1 is very simple, just use instruction MOV P1, A analog scale with the understanding that wish to be raised previously been stored in the accumulator A.
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