Wednesday, February 2, 2011
3 Digit Digital Frequency Counter
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| Digital Frequency Counter Circuit |
This circuit is a digital frequency counter. It covers region 1HZ until 1MHZ. The IC1 schmitt trigger that it regulates the signal of entry and him changes in reasonable level suitable for the IC2-3-4. With the tenth pulse in the entry of IC2/1, is produced a pulse '' carry '' in the IC3/5. The same moment the IC2 causes the depiction in the display 1, The IC3 causes the display 2. When in the entry of IC3 it reaches and the tenth pulse, the display 2 and the display 3, (with total depiction 100, having the display in right order). The exit '' carry'' off IC4/5, can be used in order to it turns on the decimal point (comma) the display 1, in order to it shows a situation over the limits of measurement.
The timed begins with the one of half double timer (IC5A). Switch S1 select the interruption the time in 1sec or in 1ms. At the duration of this interruption, second half the (IC5B), it produces a interruption of depiction 2 or 3sec., at the duration which counter cut off by the entry and the displays remain OFF. In the end of depiction, a pulse RESET, begins the interruption of time/depiction.
The critical point is round the Q1-IC1, which should be placed as long as it becomes more near in the jack of entry, to reject of parasitic signals of high frequency. For the regulation, we can use a frequency counter good precision (if you do not have you are lented) and a generator of signal. We put switch S1, in place [HZ], we apply in the entry a low frequency and we regulate the trimmer TR2, so that we take the right clue, which should suit with source frequency counter We repeat also the regulation for the department of KHZ, with a higher frequency. The supply of circuit becomes with a battery +9V, if it is used as portable or from suitable power supply if it is incorporated in some unit that exists already.
List Component
The timed begins with the one of half double timer (IC5A). Switch S1 select the interruption the time in 1sec or in 1ms. At the duration of this interruption, second half the (IC5B), it produces a interruption of depiction 2 or 3sec., at the duration which counter cut off by the entry and the displays remain OFF. In the end of depiction, a pulse RESET, begins the interruption of time/depiction.
The critical point is round the Q1-IC1, which should be placed as long as it becomes more near in the jack of entry, to reject of parasitic signals of high frequency. For the regulation, we can use a frequency counter good precision (if you do not have you are lented) and a generator of signal. We put switch S1, in place [HZ], we apply in the entry a low frequency and we regulate the trimmer TR2, so that we take the right clue, which should suit with source frequency counter We repeat also the regulation for the department of KHZ, with a higher frequency. The supply of circuit becomes with a battery +9V, if it is used as portable or from suitable power supply if it is incorporated in some unit that exists already.
List Component
R1 : 8.2Mohm IC2-3-4 : 4026
R2-9 : 100Koh IC5 : 556
R3 : 470Kohm IC6 : 4007
R4 : 470 ohm IC7 : 7805
R5-6-7 : 10Kohm DS1-3 : Display 7segment Comm. Cath.
R8 : 3.3Mohm TR1 : 1M ohm trimmer
C1-2 : 1uF 63V Mylar TR2 : 1Kohm trimmer
C3 : 47uF 16V Q1 : 2N930
C4 : 100nF 63V S1 : ON-OFF mini switch
C5 : 2.2uF 16V S2 : 1X2 mini switch
C6 : 10uF 16V
C7 : 10nF 63V Mylar
C8-10 : 1nF 63V Mylar
C9 : 1uF 16V
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