1) CPD is defined as the value of the IC’s internal equivalent capacitance which is calculated from the operating current consumption without load. (Refer to Test . Integrated Circuit. Transistor Transistor Logic (TTL). 4−Line−to−16−Line Decoder /Demultiplexer. 24−Lead DIP Type Package. Description: The NTE is a. datasheet, circuit, data sheet: NSC – 4-Line to Line Decoders/Demultiplexers,alldatasheet, datasheet, Datasheet search site for.
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Sign up using Email and Password. The input arrangement of the MT provides a differential input operational amplifier as well as a bias source VREF to bias the inputs at mid-rail.
The main theme of this project is to control the devices using telephone.
(PDF) 74154 Datasheet download
Here we use the transistors to energize the relay coil. Control the light of advertising board: It makes accurate switching, any false switching of device are not done. In 47154 time interval the output of the tri state buffer will be the signal at its input terminal. Each device is given a unique code. This check is performed by an external RC time constant driven by ESt. Before going into detail of the circuit, we will take a brief description about integrated circuits used in local control section.
For the proper working of this local control section except the local telephone set it needs a permanent back up which gives a 5V back up continuously. The DTMF mode is shortly called as tone dialing mode. By pressing any key in the keyboard corresponding DTMF signal is available in its output pin at pin no. These signals are digital signals which are symmetrical with the sinusoidal wave.
For example, if the target application requires 16 7-segment LED displays, but your microcontroller only has 4 lines to select which display lf active, this chip 74LS would provide a very effective method of essentially multiplying you selecting lines by a 4 dayasheet.
After a period of 5 seconds the output of the IC 6 goes low and puts the tri state buffer in the high impedance state. The dialed number of the device is displayed on seven segment display. Here common anode seven segment display is used. By this the device is switches ON.
Before changing the state of the device we can confirm the present status of the device. Check for availability of tone dialing mode in your telephone set. This intern switches on the relay. Now make a call to your telephone set using a remote telephone set or mobile phone. A seven segment display has seven LEDs connected in a sequence to give a regular shape and a LED to display the dot for decimal point.
Device Control Using Telephone:
You can control up to 10 devices. The actual implementation of the chosen ic has active low outputs.
The connecters are provided to all the relay switches so that the devices are connected easily. This circuit identifies the ringing signal sent from the telephone exchange. Now you will hear the feedback tone because the device is switched ON.
Repeat the step ii. It is active low output IC so when any output line is selected it is indicated by active low signal, rest of the output lines will remain active high.
Its decoder uses digital counting techniques to detect and decode all 16 DTMF tone pairs into a 4-bit code. The demultiplexing function is performed by using the 4 input lines to address the output line, passing data from one of the strobe inputs with the other strobe input low.
This gives a triggering pulse to monostable multivibrater which is build around the IC 6. This feedback tone is heard only when the device is switched ON.
This is a control unit through which you can control your appliances. This frequency comes in the audible range between 40Hz to Hz. The ring detector circuit is built around a monostable multivibrater constructed around timer IC While switching OFF the device this tone is 47154 heard. Make sure that the installation of the local control section is perfect; every thing is ready and local control section is ready to receive signal from remote section. This IC gets a backup from a 9V battery.
When this key is pressed the oc of the line decoder goes low.
The LED can be chosen at random by the status of the 4 line selector inputs. A parallel connection from the telephone line is taken and connected it to telephone interfacing circuit using a DPDT switch.