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Digital Alarm Clock (IC-TMS-8560)

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Digital Alarm Clock (IC-TMS-8560)

  1. 1. St. Xavier’s College, Ahmedabad DIGITAL ALARM CLOCK USING IC TMS 8560 CHINTAN PATEL ROLL NO: 247 UNI NO: ______
  3. 3. 3 INTRODUCTION: The Tms-8560 is a digital alarm clock each chip includes all the logic required to bold server types of clocks and timers with a digital display mode. Hours, minutes, alarm display settings, alarm off setting is done via the standard set buttons when the chip is in the various display modes. A digital clock is a type of clock that displays the time digitally, i.e. in numerals or other symbols, as opposed to an analog clock, where the time is indicated by the positions of rotating hands. Digital clocks are often associated with electronic drives, but the "digital" description refers only to the display, not to the drive mechanism. (Both analog and digital clocks can be driven either mechanically or electronically, but "clockwork" mechanisms with digital displays are rare.) Digital clocks typically use the 50 or 60 hertz oscillation of AC power or a 3.2768 Mega hertz crystal oscillator as in a quartz clock to keep time. Most digital clocks display the hour of the day in 24 hour format, a more commonly used hour sequence option is 12 hour format (with some indication of AM or PM). Emulations of analog-style faces often use an LCD screen, and these are also sometimes described as "digital".
  4. 4. 4 To represent the time, most digital clocks use a seven-segment LED, VFD, or LCD display for each of four digits. They generally also include other elements to indicate whether the time is AM or PM, whether or not an alarm is set, and so on. Most people find difficulty in setting the time in some designs of digital clocks in electronic devices where the clock is not a critical function, they may not be set at all, displaying the default after powered on, 00:00 or 12:00. Digital clocks that run on mains electricity and have no battery must be reset every time the power is cut off or if they are moved. Even if power is cut off for a second, mostclocks will still have to be reset. This is a particular problem with alarm clocks that have no "battery" backup, because even a very brief power outage during the night usually results in the clock failing to trigger the alarm in the morning. To reduce the problem, many devices designed to operate on household electricity incorporate a battery backup to maintain the time during power outages and during times of disconnection from the power supply. More recently, some devices incorporate a method for automatically setting the time, such as using a broadcast radio time signal from an atomic clock, getting the time from an existing satellite television or computer connection, or by being set at the factory and then maintaining the time from then on with a quartz movement powered by an internal rechargeable battery.
  5. 5. 5 BLOCK DIAGRAMOF DIGITAL ALARM CLOCK: Because digital clocks can be very small and inexpensive devices that enhance the popularity of productdesigns, they are often incorporated into all kinds of devices such as cars, radios, televisions, microwave ovens, standard ovens, computers and cell phones.
  6. 6. 6 LIST OF COMPONENTSUSED IN THIS MODEL: IC1 – TMS 8560 IC2 – CD4541B IC BASE- 16 PIN CRYSTAL – 3.2768MHz DISPLAY- 7 SEGMENT DISPLAY R1,R2,R3,R4,R5 – 1KΩ, 1/4Watt per resistor R6 to R19 - 380Ω R20 – 1MΩ C1- 1000µF/25V C2,C3 – 10Pf Transistor (Q1,Q2,Q3,Q4)-BC547 Diode (D1,D5,D6,D7)- IN4007 Switch: Push to ON (4 pcs) 9v battery for back-up Adaptor : i/p = 90-270V with 50-60Hz frequency o/p = 12V dc with 1A max current 18W= max power dissipation LED: 3mm (2 pcs) Buzzer : 1pc
  7. 7. 7 SPECIFICATIONS: 1) The chips used in this model of digital alarm clock operate over a wide range and low stand by operating voltage facilities 2) 7 segment display. 3) Alarm on a 24 hour basis 4) Battery back-up. (in-case of power failure) 5) 50Hz/60Hz is usable as the reference frequency. 6) Single DC power supply 7) AM output (This is pictorial representation of this model)
  8. 8. 8 CIRCUIT DISCRIPTION: The following figure is the pictorial representation of the circuit diagram of alarm clock.
  9. 9. 9 This is the X-Ray scan of the pcb in the model:
  10. 10. 10 In the above mentioned circuit a BC547 transistor is a negative-positive- negative (NPN) transistor that is used for many purposes. Together with other electronic components, such as resistors, coils, and capacitors, it can be used as the active component for switches and amplifiers. Like all other NPN transistors, this type has an emitter terminal, a base or controlterminal, and a collector terminal. In a typical configuration, the current flowing from the base to the emitter controls the collector current. A short vertical line, which is the base, can indicate the transistor schematic for an NPN transistor, and the emitter, which is a diagonal line connecting to the base, is an arrowhead pointing away from the base. There are various types of transistors, and the BC547 is a bipolar junction transistor (BJT). There are also transistors that have one junction, such as the junction field-effect transistor, or no junctions at all, such as the metal oxide field- effect transistor (MOSFET). During the design and manufacture of transistors, the characteristics can be predefined and achieved. The negative (N)-type material inside an NPN transistor has an excess of electrons, while the positive (P)-type material has a lack of electrons, both due to a contamination process called doping. This diode IN-4007 is basically the rectifier diode used for the rectifier purposes. his is a simple, very common rectifier diode. Often used for reverse voltage protection, the 1N4007 is a staple for many power, DC to DC step up, and breadboard projects. 1N4007 is rated for up to 1A/1000V.
  11. 11. 11 In the circuit IC-TMS8560 pin diagram: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 28 27 26 25 24 23 22 21 20 19 18 17 16 15 10S HR AG & DE PM & 10S HR B 10S HR C & HR E HR B & G HR C & D HR A & F 10S MIN A & F 10S MIN B & G 10S MIN C & D 10S MIN E & MIN E MIN B & G MIN C & D MIN A & F COLON OUT 12/24 SELECT C R INPUT 50/60Hz SELECT 50/60Hz INPUT SNOOZE INPUT SLEEP INPUT HOUR SET MIN SET Vss (-) ALARM DIS ALARM OFF SLEEP OUT ALARM OUT Vdd (+)
  12. 12. 12 How it works? In this circuits, the heart of the circuits are IC1 (LM8560), Which has output the 3 way are: 1. The output for drive display Duplex Model numbers (pin 1-14) 2. The output provide alarm signal at pin 16. 3. The output to control electrical appliances with automatic timer. Two R1, C1 together with was integrating circuit to Provide input to the clock signal 50 Hz input lock pin (pin 25) of IC1. Two diode D1, D2 are the switch signal generators to the cathode of display number for working alternately and relation with the input of IC1. The alarm signal from pin 16 of IC1, will be entered to the potentiometer P1(Volume), to pin 3 of IC2 (LM386), that is alarm signal amplifiers to drive the loudspeaker. The P1 so is fine a alarm sound pressure as you want. And the sleep out signal from pin 17 that you can continue to use, to control another circuits.
  13. 13. 13 IC CD4541 PIN DIAGRAM: RC TIMER/COUNTER (CD4541): The RC Timer is used to implement the 5 minute swap of sounds between buttons. This chip, as set up here, emits a square wave with a 10-minute period. When the output changes level, the sounds are swapped. The CD4541BC programmable timer has a 16 stage binary counter, an integrated oscillator that uses an external capacitor and two resistors. The timer is also programmable by setting the digital inputs to divide the oscillator frequency by to 2^8, 2^10, 2^13, 2^16. The CD4541BC oscillator frequency can be set by an external RC network that's by the following formula freq = 1 / (2.3 * Rtc * Ctc) where Rs = ~ 2Rtc and Rs >= 10,000 ohms
  14. 14. 14 WORKING: First of all connect the circuit as shown above. When the circuit is turned on the display screen shows 12.00 and then we need to set the time with reference to a standard clock. The side green LED when ON states AM and vice-versa indicates PM. In order to set time the switches are provided (hour, minute, alarm switch, buzzer off switch). And there is port for battery back up also which needs to be is used only when there is power failure, in this display gets off but the counter in IC doesn’t stop. And in this case if we had set the alarm it also works. TROUBLESHOOTING: In digital alarm clock basically there is no need for calibration, and hence the chances of manual error doesn’t arise. Also, we need to keep in mind that all the components connected are of proper values so the clock works properly. So the major factors responsible for the malfunctioning of the digital alarm clock can be: 1. Problem in input suppy. 2. Transformer can be out of order or may be burned out due to high current or may be the input port may be faulty. 3. Problems with the control buttons as they are mechanical switches, due to frequent use of switches it may not work.
  15. 15. 15 4. Problem with the display screen (shorting of any pins or any kind of damage to the display IC). 5. If above mentioned all the factors are not responsible for the malfunctioning of the clock than now we must look out in to the active devices. Firstly we must checkout the IC’s in the circuit. 6. As there is no particular method to find out the fault in the IC, the only option is to replace it with another one. We first do this because we don’t need to deshoulder the IC as a stand is shouldered on the PCB and the IC is mounted on this stand. 7. The next step is to check out with the buzzer if the problem is only with sound. 8. If still the problem continues, now we must checkout with the transistors and the diodes. We can do so by connecting the multimeter between different terminals and by looking out for the proper voltage drops between the terminals for proper functioning. RESULTS: The time shown by this model is almost accurate with the time shown by the time shown by the standard clock. the uncertainity of the clock is almost less then 1% .