Schematic Diagram: display

Showing posts with label display. Show all posts

Saturday, November 8, 2014

Telephone Number Display Circuit Diagram

The given circuit, when connected in parallel to a telephone, dis- plays the number dialled from the telephone set using the DTMF mode. This circuit can also show the number dialled from the phone of the called party. This is particularly helpful for receiving any number over the phone lines. The DTMF signal—generated by the phone on dialling a number—is decoded by DTMF decoder CM8870P1 (IC1), which converts the received DTMF signal into its equivalent BCD number that corresponds to the dialled number. This binary number is stored sequentially in 10 latches each time a number is dialled from the phone. The first number is stored in IC5A (1/2 of CD4508) while the second number is stored in IC5B and so on.

The binary output from IC1 for digit ‘0’ as decoded by IC1 is 10102 (=1010), and this cannot be displayed by the seven-segment decoder, IC10. Therefore the binary output of IC1 is passed through a logic-circuit which converts an input of ‘10102’ into ‘00002’ without affecting the inputs ‘1’ through ‘9’. This is accomplished by gates N13 through N15 (IC11) and N1 (IC12). The storing of numbers in respective latches is done by IC2 (4017). The data valid output from pin 15 of IC1 is used to clock IC2. The ten outputs of IC2 are sequentially connected to the store and clear inputs of all the latches, except the last one, where the clear input is tied to ground. When an output pin of IC2 is high, the corresponding latch is cleared of previous data and kept ready for storing new data. Then, on clocking IC2, the same pin becomes low and the data present at the inputs of that latch at that instant gets stored and the next latch is cleared and kept ready.

The similar input and output pins of all latches are connected together to form two separate input and output buses. There is only one 7-segment decoder/driver IC10 for all the ten displays. This not only reduces size and cost but reduces power requirement too. The output from a latch is available only when its disable pins (3 and 15) are brought low. This is done by IC3, IC12 and IC13. IC3 is clocked by an astable multivibrator IC4 (555). IC3 also drives the displays by switching corresponding transistors. When a latch is enabled, its corresponding display is turned on and the content of that latch, after decoding by IC10, gets displayed in the corresponding display. For instance, contents of IC5A are displayed on display ‘DIS1,’ that of IC5B on ‘DIS2’ and so on. The system should be connected to the telephone lines via a DPDT switch (not shown) for manual switching, otherwise any circuit capable of sensing handset’s off-hook condition and thereby switching relays, etc. can be used for automatic switching.

The power-supply switch can also be replaced then. Though this circuit is capable of showing a maximum of ten digits, one can reduce the display digits as required. For doing this, connect the reset pin of IC2, say, for a 7-digit display, with S6 output at pin 5. The present circuit can be built on a veroboard and housed in a suitable box. The displays are common-cathode type. To make the system compact, small, 7-segment displays can be used but with some extra cost. Also, different colour displays can be used for the first three or four digits to separate the exchange code/STD code, etc.

Sunday, September 14, 2014

– Voltage On Bargraph Display

The LM3914 is a truly versatile component. Besides LEDs, only a few other components are needed to make the ‘bidirectional’ bargraph voltmeter shown here. The schema is similar to a conventional bar display, but it offers a possibility to change the direction in which the LEDs are switched on. This may be useful, for example, when positive and negative voltages are measured. For a positive input voltage, the LEDs are switched on in the usual manner, that is, from D3 to D12, while for negative voltages, the LEDs are switched on in the opposite direction, from D12 to D3. Obviously, the negative voltage must be ‘rectified’, i.e. inverted, before the measurement.

A suitable schema for this purpose is presented in the article ‘Absolute-value meter with polarity detector’ elsewhere in this website. A set of transistor switches (MOSFETs) controls the direction in which the LEDs light. When the control voltage is high (+6V, according to the schematics, but any voltage that is at least 3V higher than reference voltage will do), T1 and T4 are switched on, while the other two MOSFETs are off. In this way, the LM3194 is configured in the usual manner with the top end of the resistor network connected to the internal voltage reference and the low end connected to ground.

+/– Voltage On Bargraph Display Circuit Diagram

As the input voltage rises, the comparators inside the LM3914 will cause the indicator LEDs to be switched on one by one, starting with D3. When the control voltage is lower than about –3V, T2 and T3 are switched on while T1 and T4 are off. Consequently, the ends of the resistor network are connected the other way around: the top end goes to ground and the low end, to the reference voltage. The first LED to be switched on will then be D12; i.e., the LEDs that forms the bargraph display light in the opposite direction. Although not documented by the manufacturer of the LM3914, this option works well, but only in bar mode (in dot mode, internal logic disables any lower-numbered LEDs when a higher-numbered LED s on, which obviously conflicts with our purposes).

To achieve good symmetry, an adjustable resistor is added to the voltage divider in the LM3914. Using a DVM, adjust the preset until the voltage across P1+R4 equals 1/11th part of Urefout. Sensitivity is determined with the ratio of resistors R5 and P2. If, for example, the reference voltage is set to 2.2 V by means of P2, there will be a voltage drop of 200 mV per resistor in the ladder network (including R4-P1). So, the first LED will switch on when the input voltage exceeds 200 mV, the second, at 400 mV, and so on, and the whole display will be on at 2 V. The schema draws about 100 mA when all LEDs are switched on.

Monday, September 8, 2014

IR Infra Red Sensor with 7 Segment Display

Infrared light has a difference with ordinary light in general. We can see clearly when a light or light on an object.

As with the infrared light we can not see the manifestation of these rays. Frankly I can not answer when asked why the infrared rays are not visible in the eyes of us. So at night do not hope you can make light by using infrared light. One thing that is often heard from many people that infrared light can utilized for the functions of a camera that can see in dark conditions is often called an infrared camera.

Actually I have explained the working principles of electronic circuit section in this blog is about the basic working principle of a series of infrared sensors are simple. To design this sensor circuit you should not find trouble if you ever make another series of sensors. Its just that the sensor circuit consists of the transmitter and receiver, to learn the basic principles of this series of infrared you can see in the Basic Principles Series Infrared Transmitter and Receiver. In the circuit this time I try to utilize the output of this sensor circuit as a trigger circuit counter or counters.

Picture series of infrared sensors | infrared sensor circuit scheme

Component List:

1. Resistors: R1 (33K), R2 (1K), VR1 (Potensio 100K)
2. Capacitors: C1 (100nF)
3. Transistors: Q2 (BC547 should)
4. Photo transistor: Q1
5. IC: 40 106 (Schimitt trigger), 4026 (Decade counter)
6. 7-Segment

WORKING PRINCIPLE:

In the transmitter circuit arrangement so that our task is only an infrared LED lights up and no shortage or excess of power, therefore, use 680 ohm resistors. On The set of photo transistor receiver serves as a useful tool sensor sensed a change in the intensity of infrared light. When infrared light is not on the photo transistor, the photo transistor is like a switch is open so that the transistor is in cutoff position (open). Because the collector and emitter open it in accordance with the laws of the voltage divider, the collector emitter voltage equal to supply voltage (logic high). The output of these collectors would make a series of counter counting irregularly if we did not dampen the bounce output to the input couinter. To reduce the bounce and clarify the logic signal to be our input to counter circuit, we use Schmitt trigger ignition. Schmitt trigger ignition is very useful for those of you who relate to digital circuits, eg, using the damping bounce of mechanical switches on the input digital circuit.

The series of counters that I use here is to use IC 4026 (Decade Counter), one of the family ic CMOS. IC counter counts up if this will get the clock input changes from logic low to high. This IC can directly connect it to the seven segment because the output is designed for seven segment mmang. So you do not need to use as a modifier decoder IC binary value into a score of 7-segment.

To menmgatur you can rotate the sensor sensitivity potensio VR1 at a critical point, or if necessary you can replace R2 with a more appropriate value.

Saturday, August 30, 2014

Build a Lcd Display Power Supply Wiring diagram Schematic

This is the simple Lcd Display Power Supply Circuit Diagram. Laptop computers often use large-screen LCDs, which require a variable and a negative supply to ensure maximum contrast. This schema operates from the system`s positive battery supply and generates a digitally variable negative voltage to drive the display. This figure`s switching regulator creates a negative voltage from the battery supply. The microprocessor data bus drives a 4-bit DAC, which in turn varies the actual regulator output from - 6.5 to -11.5 V.

Lcd Display Power Supply Circuit Diagram

This arrangement allows a staircase of 16 possible voltages between these limits. The schema implements the DAC by using the rail-to-rail output-drive capability of a 74 HC-series CMOS gate. A resistor divider network formed by the 240-kfi resistor, connected to the -V filter capacitor and the resistors, is referenced to the 5-V supply control (the MAX635 regulator).

When the voltage at the VFb pin is greater than ground, the switching regulator turns on. The inductor dumps this energy into the -V filter capacitor. When the voltage at VFb is less than ground, the regulator skips a cycle. The MAX635 regulates the voltage at the junction of the resistor divider to 0 V. Thus, any resistor that the DAC connects to ground (logic 0) will not contribute any current to the ladder. Only the resistors that are at 5 V (logic 1) will be part of the voltage-divider equation.

The entire switching-regulator supply draws less than 150 . You can place the schema in an even lower power mode by interrupting the ground pin. The high-current path is from the battery input through the internal power PMOSFET to the external inductor. Disconnecting the ground connection simply disables the gate drive to the FET and turns off the internal oscillator.