The digital clock of circuit, has as base one IC, the MM5314N, in which are contained all the circuits that need. The IC1 collaborates with six display of common anode, that are not critically as materials. You can select what dimension, you want it is enough you adapt pins their in the circuit. The display are drive by a system of polyplexis and are drive by thirteen transistors. For timing the circuit, is used the frequency of network 50HZ.
This solution is the simplest, that it is not best. For more constant frequency you can use a circuit that would be based on crystal, (it will be given shortly). For the clue of hour are used six display of 7 element common anode. The DS1-DS2, show the hours (decades-unit respectively), the DS3-DS4, show the minutes and DS5-DS6, the seconds. The common anode, for each display is drive by the collector of transistors Q8 until Q13. Individual led (a, b, c, d, e, f, g) the display, they are linked between them (parallel) and are drive by the transistors Q1.. Q7, creating thus a system multiplexing, to frequency 1KHZ, that is determined by the R3-C3. The power supply is a classic circuit, from T1 and GR1, C1. The remainder capacitors as the C2-C5 and the R5 make local unyoke of voltage and protect the IC1 from peaks of voltage. The diode D1, limit the top, of rectified vibrations in the pin 16. Resistances R18…24, limit the current that leak the led. With switch S1 in place 2, the clock measures the time and the display remains openly, with the S1 in place 1, the display they remain closed, the clock however continues working. This operation us allows to have the clock in spaces that we do not want exists the lighting of display. With the S2 in place 1, we have measurement in 12-hours base while in place 2, we have measurement in 24-hours base. With the S3 in place 1, we see the measurement in seconds, while in place 2, we only see the measurement in hours and minutes, while the seconds do not function. With switches S4, S5, S6, we make the regulation of hour when exists some interruption in the operation of clock, and becomes with the classic way that usually becomes in this type the clocks. The pin 11 [ 50/60 of HZ Select ] is the input with which we select the operation of MM5314 in main voltage frequency 60HZ or 50HZ. When we have main voltage 110Vac- 60HZ [USA system] then the pin 11 is connected in Vss @pin 2. If the main voltage is 220Vac – 50HZ [Europe system] the pin 11 is not connected nowhere, remain that is to say in air. Pin 16 [50/60 input], is the input, where is applied sample from the main voltage [50HZ or 60HZ]. With this sample function the counter circuits and become the measurement of time. Thus if you have 220Vac/50HZ, then the pin 11 remains void. If you have 110V/60HZ, then the pin 11 it’s connected in Vss @ pin 2.
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