Hello to all, its my very first post and i just beggined in electronic.

I started one month ago when i looked at howstuffwork on electricity and got in love with it.

So i decided to make my first project a 1 to 100 counter .

The idea is simple(with a 5 volt dc supply):

555 timer---bcd binary counter--7 segment display decoder--7 segment display. (For units)

The 2nd display works the same way but get a 1/10 frequency then segment of units, so it count the ten's. ( i use a third 7490 to divide by ten)

I would need your advice, maybe i would need to put a capacitor somewhere but i dont know because i am a noob that just started and there may be some minor imperfection in the design(like no power supply to a chip)

I would need to know if the 7447 and 7490 chips still exist in the same format because the only datasheets that i founded where from 2000

Please answer me.

a noob

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hi,

With a quick look at your circuit you appear to have 3, 7490 counters and only 2, 7447.

Do you need to count to 100 or will 0 to 99 do.?

Also you can get those ic's.

EDIT:
To make the 7490 a decade counter, [ 0 to 9] the clock input is pin 14, then link 12 to pin 1.

The output clock for the next 7490 is from pin 11 of the first to pin 14 of the second 7490 [ on the second also link pins 12 and 1]

this will then count fro 00 thru 99 and start again at 00.

connect pins 2 and 3 for a 'reset to 0'

OK.?

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Breadboard Man

Your circuit is rather confused,
the first counter is OK from the 555 to count the 1s,
but the 10s counter does not need a divider as you have.

Take the D output from first counter pin 11 and connect into the clock of the second counter. (See my modified version of your circuit).

JimB

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Thanks to had replyed.

So now my circuit will be able to count to 0 to 99(i mean the modified version).

Do you think i can fit all that on a single breadboard?

 

There is something that i dont understand

if d get high when 1000

it should go high 2 time in 10 time sequence

1000 and 1001(8 and 9th inputs of clock)

can someone explain me?

 

The D output remains high during the 8 (1000) to 9 (1001) transition.

JimB

__________________
Experience is directly proportional to the value of the equipment ruined.