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:: ( رحمه الله عليه ) ::
تاريخ التسجيل: Feb 2009
الدولة: لا تسأل الطغاه لماذا طغو بل اسأل العبيد لماذا انحنو
المشاركات: 3,126
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نشاط [ عريبى محمود ]
قوة السمعة:
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08-06-2011, 01:13 AM
المشاركة 9
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دائرة تاخير
السلام عليكم
Timer
Circuit diagram
This timer can be set to count a maximum of 60 hours. It also allows an interval to be set. When this interval is reached, a buzzer sounds. The larger part of the circuit is contained in an Intersil Type ICM7217 four-digit CMOS up/down counter and display. Circuit IC3 is the clock that generates a square wave with a period of 1 s. The clock signal is available at pin 3 (Q13). The clock signal may be divided by 60 in IC4 if it is required to time more than 1 hour.
When S6 is closed, the supply is switched on and IC4 is reset via R9 and C5. The position of S4 determines whether minutes or seconds are counted: maximum 59 h 59 min (pos 2) or 59 min 59 sec (pos 1). If, for instance, a total time of 35 min with an interval at 20 min is to he counted, S4 is set to position 1. Thumb wheel switches S7 to S10 are then set he a display reading of 20.00. Briefly pressing S3 stores this setting in the memory of IC1. Then S7 to S10 are set for a display reading of 35.00. During these settings, S1 should be open. Pressing S2 causes the ICM7217C to count down from 35.00. When display reading 18.00 is reached, the buzzer briefly sounds (energized via N3 and N4). The timer may then be stopped by closing S1. When S1 is opened again, the timer restarts the down count to 00.00. When that reading is reached, the buzzer sounds briefly again. Note that at any time during the count down the timer may be stopped by closing S1.
The timer is reset with S5; when that happens, the buzzer sounds briefly and the display reads 00.00. The set count down period of 35 min is, however, retained in the memory until a new period is programmed. The current drawn by the timer, including the displays, is about 100 mA. If a battery supply is used, it is possible to switch off the displays when the timer is counting by adding a switch (with single break contact) between points A and B. This switch enables the display to be read briefly. With the displays switched off, the current drawn is of the order of only 4 mA.
Do not set the thumb wheel switches to readings greater than 59.59, because the timer will then no longer count correctly.
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السلام عليكم ورحمة الله
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