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7-Segment LED Counter (binary and base 10)

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Thread starter #1
Here is something that I was able to build, it basically takes the pulse from a 555 timer and goes through a 7490 divide by 10 into a 7448 and finally into a LN514rk Common Cathode LED-- if you are going to use a common anode LED just replace the 7448 with a 7447

Materials Needed

  • 5 V-Source
    Wires
    555-Integrated Circuit
    7490-Integrated Circuit
    7448-Integrated Circuit
    7-Segment Display (the one I used was LN514RK)

Simply connect it as it is in the diagram
http://www.quantumninja.com/hw/elec/circuitdone.jpg
 

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#2
THANKS MATE (COUNTER)

The names royd! (well nickname and DJ name actually).
I want to thank you for the 7 seg counter diagram, you say your a novice
but beleive me they named the word novice in electronics after ME!!!"
Im very willing and try hard to learn, i have a room full to the brim of parts
from the past two years of pure guess work.
Nothing ever really comes to light though, i wouldnt say im thick but it aint easy is it, i usually av a go mess it up, spend three days trying to figure what
went wrong, then get seriously frustrated and end up sticking the girl freind
in the fridge (joke).
I really want to get results though as ive plenty of good ideas mainly security
projects that could make money.
plenty of idea's, none or little build knowlage, always the way hey?
Any way your project doesnt look to bad so im going to have a crack at it,
best go church first pray a bit.
I will let you no how ive done, and please if you want to help me in any way with electronics ide be dambed gratefull.
E-mail me anytime
roydpro@yahoo.co.uk

thanks again
royd out...
 
#3
7 segment

hey i duno why u have used 200 ohms Resistance with Diode in 555 timer & same in 7490 ? Well would u like to answer me or can u explain da ciruit in more detial thanks waiting for reply

Azam Jiva
 
#4
How to drive 3 7-segment display

Situation:
I have 3 7-segment display and i want it to display numers form 0-999.

The Problem :
Using a 7447 i can display from 0-9,A,B,C,D,E,F in one of the 7-segment display.
But how can i connect the 3 7-segment display in order to display from 0-999
 

AllVol

New Member
#5
Hi jnkevin,

Refer to my attachment below. For each individual digit, you need a counter, driver and 7-segment LED. To count beyond one digit, simply connect pin 11 of each 7490 to pin 14 of the next 7490.

AllVol
 
Last edited:

AllVol

New Member
#7
Hi weilst

Welcome to the forum and thanks for your question. In the circuit you mention, the 555 timer is being used as what we call an astable multivibrator, meaning that it generates one pulse (or count) in a regular pattern. To manually produce a pulse would simply involve replacing the 555 timer with a switch connected to pin 14 of the 7490. Each time you close the switch, the counter advances by one.

However, a switch will open and close rapidly because of its mechanical nature, resulting in "switch bounce" which will cause false counts. There are a number of circuits you can use between the switch and pin 14 to eliminate switch bounce. Look up switch bounce on Google for circuits.

Good luck,

AllVol
 
#8
weilst said:
This is a reat circuit, how would i go about controling 2 7 segment leds that I could increase by pressing a button?
In order to control two 7 segment displays using a circuit similar to the one above, you'd need two binary counters and two display drivers. The second binary counter would need to be clocked by the overflow of the first using some simple logic gates.

Brian
 

AllVol

New Member
#9
Yep, that's right. I meant to add that, but was in a hurry and forgot. Thanks, Brian.

Edit: However, following a closer reading of your comment, you indicate seperate gates are necessary for the clocking of the second counter. Incorrect. The second counter will be clocked directly by the first. See reply #6. Only if one wishes to reset after some number less than 9 would one need to use a logic gate.

Allvol
 
Last edited:
#10
Tom

See...this is the type of circuit that the groups need more of. Simple, good, clear instructions...not 2 many parts.
Just look at the amount of interest this simple little circuit has stirred up.
keep up the good work
Kim:D
 
#13
diodes cathod connections

you have done very good job.but i confused at one point that where you have connected the diode's cathods in 7490 ic ckt.to ground or +5v.thanx
 
#16
Tom McCurdy said:
Here is something that I was able to build, it basically takes the pulse from a 555 timer and goes through a 7490 divide by 10 into a 7448 and finally into a LN514rk Common Cathode LED-- if you are going to use a common anode LED just replace the 7448 with a 7447

Materials Needed

  • 5 V-Source
    Wires
    555-Integrated Circuit
    7490-Integrated Circuit
    7448-Integrated Circuit
    7-Segment Display (the one I used was LN514RK)

Simply connect it as it is in the diagram
http://www.quantumninja.com/hw/elec/circuitdone.jpg
ei, can you send me a pcb design for this circuit,.using common anode,.,.
,.plz,.it would be a great help guys,...thank's.,.:)
e-mail;
eiluj_872001@yahoo.com
 
#17
Hello!

I'd need help/advice of what can be wrong in my pulse counter.
It is based on 7490+7447+common anode 7-segment displays.
There are 3 phases, i.e. it counts from 000 to 999.

Generally everything's ok, but the pin 11 of the 7490's raise too often,
about randomly. It should raise every 10th pulse, right?
With oscilloscope I could see quick peaks in the 7490's Qx outputs.
What can be wrong? I've checked many times the connections
with magnification.
 
#19
I don't see any bypass caps. You should have a capacitor (I like 0.1uF for 7400 series chips) from 5V to GND near every chip. 0V probably should be connected to gnd.

The detector should have some hysteresis; see if a 7414 works better in place of the 7404.
 
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