how can i implement this circuit using BCD counter...... plz help me

[syedamehakfatima]

We are going to create a circuit using sensor that when you are passing to enter in the sensor the 7 segment will count increment and when you passing back the sensor will be decrement....

What kind of sensor and Components am i going to use???

Help me plz........

 

[mister_rf]

You may find a similar project here: :-D
https://www.edaboard.com/threads/245903/

 

[barry]

That's a pretty broad request. I think you probably want to use photo-electric sensors, and you will need at least two of them in order to determine whether you are coming or going. You can use a small microprocessor, or discrete up/down counters and decoders.

 

[mister_rf]

See the people counter circuit in action:
:-D

Minor changes to the previous schematics:

 

[syedamehakfatima]

thanx alot for your help..... how can i implement this circuit with only 1 digit of BCD.... plz rpl fast any body cuz i have to submitt my project proposal tomorrow.... plz

 

[Arch Zone]

erase that three components on the right side

 

[syedamehakfatima]

thanx alot...

 

[syedamehakfatima]

can u explain that what logic u use in CLR pin of 74LS192?? and why u ground all inputs of 74LS192.?

 

[betwixt]

The inputs on the 74LS192 are to pre-set a value to start counting from. Wired as they are, the number is set to start counting up from zero.
The CLR pin can be driven high to force a reset but you can just use the circuit in the lower yellow box. Note that to work properly, the supply voltage must rise fairly quickly. Just switching 5V on is fine but if you raise the voltage slowly the reset circuit may not work.

Brian.

 

[syedamehakfatima]

instead usind BCD counter ic i have to implement a counter my self using D-flipflop plz help me how to implement it... plz rpl fast plz

 

[betwixt]

Look at the data sheet for the 7490 (74LS90, 74C90 etc.) the internal logic is shown which is nothing more than flip-flops in series and some glue logic. Should give you a clue.

Brian.

 

[mister_rf]

One example of such up/down counter using D flip-flops here: (this need to be modified for a BCD counter)
**broken link removed**
read more here:
https://www.electronics-tutorials.ws/counter/count_1.html
https://www.electronics-tutorials.ws/counter/count_3.html
https://www.electronics-tutorials.ws/counter/count_4.html
https://www.allaboutcircuits.com/worksheets/counters.html

**broken link removed**

You may use LOGISIM to test the counter: (Logisim is a free logic simulator which permits circuits to be designed and simulated using a graphical user interface),
download LOGISIM here:
https://sourceforge.net/projects/circuit/

 

[D.A.(Tony)Stewart]

LS192 counter is >40yr old solution is fine but PIC software counter is better, but Opto solution will not work.

You need to define precise conditions that will be detected of person walking, vs hands vs cart, vs kids, vs parcels at various height and width of entrance. Also speed of moving person needs to be defined Min & Max.
The result will be a sequential trigger of both sensors of which is decoded to validate and stretch out the event as either an entry or exit, but is non-triggerable during that event to avoid multiple counts. Then the sensitivity of the "communication path" and error rate must be defined. ie. 0.1% error rate with lights flashing on and people carrying bags or briefcases. This is critical , before any implementation can be considered. Solution might be poor single sided human reflection or cross path mirror path interruption or cross path TX to RX path interruption. Beam width of TX and Beam width of Rx must be defined in "SPEC" before design of detector. So write a Spec with inputs, processing and outputs. with measureable stress conditions and tests to verify or validate detection error rate. False triggers (aka false positive) and Missing triggers ( aka true negatives) all this is part of your design spec. dont worry about exact solution yet

 

[mister_rf]

... but Opto solution will not work.

No need to read between the lines to discover that’s only a theoretical project… Anyway, even in practice this optical solution may work if we have a good sensor placement (see the video i have attached in post #4 ;-) ).

 

[D.A.(Tony)Stewart]

I suppose sensors that are passively blocked with motion in each direction, but then they use mechanical turn-styles for more reliable counting.

as you know, It is better to learn Rules of Design (early) with at least thinking about what makes a design good, rather than a theoretical unpractical solution. Its all about details of what is need to make it really work or fail. In 1st year Physics in 1970 we learnt how to calculate our lab test stats for validity. Now we ought to be able to articulate our design requirements numerically for validation testing. Comparing theory with results. details.. details...

---------- Post added at 21:29 ---------- Previous post was at 21:18 ----------

I suppose sensors that are passively blocked with motion in each direction, but then they use mechanical turn-styles for more reliable counting.

as you know, It is better to learn Rules of Design (early) with at least thinking about what makes a design good, rather than a theoretical unpractical solution. Its all about details of what is need to make it really work or fail. In 1st year Physics in 1970 we learnt how to calculate our lab test stats for validity. Now we ought to be able to articulate our design requirements numerically for validation testing. Comparing theory with results. details.. details...

more details:
Yes dual flip flop sequence detector works on direction sensing with peak & droop transistor detector on interuption of LED. But if you stretch this path beyond a 0.25m, it will start failing and get significantly worse @ 1m. I would expect <0.1% accuracy is needed if counting revenue is involved.

 

[mister_rf]

We can extend detection path up to the moon if needed and yes, this circuit still works… :-D
Basically in practice we need to follow some small details:
-access is designed to handle only one person at a time (in or out) or may be designed as separate IN gate, separate OUT gate (but need two pairs of photo-sensors for this setup )
and
-the moving object need to cover both photo-detectors for a short period of time . This impose the maximum distance between the two sensors in order to catch the same shadow.
In practice any supplementary details to be considered (using some IR LED’s, IR filters, laser diodes) , are related to the particular configuration chosen to be covered by the optical detectors. For a normal door any LED and any photo-transistors can do the trick.
;-)

 

[syedamehakfatima]

sir i am making 4 bit BCD counter using D-flip flops for this i need just equations when x=1 and when x=0.. plz tell me is this rite or wrong???.... plz............
my sequnce is tha (D3), (D2) ,(D1), (D0) and flipflop inputs are shown as D4,D3,D2,D1. And outputs are D,C,B,A.
x=0,
D4=A'D+ABC
D3=B'C+A'C+ABC'
D2=A'B+AB'C'
D1=A'

x=1,
D4=B'C'D'
D3=B'C+C'B
D2=B
D1=A'

plz rpl me fast i have to submitt it tomorrow plz

 

[D.A.(Tony)Stewart]

>@ Mister_rf ,
Allow me to explain my concern on the Opto Design.

Short path = no issue.
Long path = some concerns

Threshold of detection is dependant on;

• gain of photo-transistor (huge variance and aging effect)
• value of emitter resistor
• noise of stray light affecting shadow levels
• strength of stray reflections while creating a shadow with arm or book
• lack of hysteresis
• lack of entropy in source information ( modulated code bits vs DC level)
• conflict with wavelength of emitted light and stray fluorescent light flicker
• need stray daylight blocking filter
• may need to specify IR vs daylight LED wavelength to avoid error
• temperature affects on photo-T gain
• may need supply noise filtering and stray E field shield ( from ESD)
• (very sensitive opto RX with very high input impedance)
• 2 LED's unless Lasers, actually adds ambiguity of shadow threshold
• Actual blocking 1 LED defines the 50% threshold, which is unknown due to lack of gain control
• lack of event pulse stretching to define non-retriggerable count time.
• asymmetric rise fall times of shadows due to variable current source
• unknown S/N ratio for variance of parts, objects and speeds

TY for allowing me to explain.

... I know there is a solution with Opto.. just not the way it was done. ( I did one long ago for detecting items in the bottom a shopping cart [Bob]

Cheers,
Tony

hmm a software BCD counter...... let's see..
http://www.interfacebus.com/Glossary-of-Terms-bcd-decimal-decoder.html

 

[syedamehakfatima]

this is BCD converter but i need a BCD up and down couter...

 

[D.A.(Tony)Stewart]

Mr_rf gave schematic for count up/dn cct. with decimal LED.

I just showed you the logic on the conversion. But there are a bunch of ways to solve this problem. First define the problem in more detail so you understand what you want to do in functions without implementation. Then define how it responds, what power is avail. how it looks, how slow or fast it has to be.
THen consider what tools you know best.. uP? CMOS hardware, PLD? SSI Logic? and start with those. Or ask a better question.

Two ways.. Count pulse and Direction logic input
or Count Up separate from Count Down
which can occur at random ( 2 aisles) or must be exclusive ( 1 aisle) Pick one

There are standard Up down counters and no need for flip flips,unless you want to do it the hard way.

You can also do in PLD or uC.

The conversion table may be useful for that.