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6 Digit 7segment Drivers and Circuits

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Gr3mlin2008

New Member
Hi there
For as long as i can remember ive always wanted to make a well, count down time as you see in moves, like a bomb timer.

So i set out doing the research.
I've gone with a mm74c912 to drive the 6 Displays.
But appart from 555 timers, and premade kits, this would be the first project i have made that uses a IC. (I know, talk about bite-ing off more than i can chew) so what i wanted to know is, firstly, does anyone know of a different IC to use as i am useing commanly Anode(?) 7seg displays and i thnk this drive a com Cathode display... but on top of that, where do i go next? LOL does anyone have a circuit diagram?
I have to some how generate a BCD signal for this chip to read, i wouldnt have the foggest how to.. any help would be great!
Cheers! :)
 

blueroomelectronics

Well-Known Member
Something like this?
4798-Dragonfly3D.png

Yea LED displays are cool.
 

Krumlink

New Member
Thats exactly what I thought of bill :)

If I were you I would continue playing with 555 timers, and when you understand the laws behind it, I would then switch over into Digital Logic. When you understand that enough it is time to start the incredably WTF easy PIC adventure.
 

Gr3mlin2008

New Member
Thats Exactly what im looking for! :)
But i want it to count backwards, like a real bomb would!

thanks for the replies guys! :)
 

Mobile

New Member
Something similar to this that I thought would be cool would be reproducing a device similar to the bomb in counter strike. You could plant it with a button that you would have to hold for like five, it would detonate after a minutes, and could be disarmed by holding down another button for five seconds. Also it could have a loud sound released to know when it's "detonated" and a time readout for effect.

It would be a fun addition to airsoft etc.
Still I would have no idea on how to go about making it
 

Gr3mlin2008

New Member
I like your thinking! :)
Maybe i should spit what i have chew out for the time being, and have a play with something that has less digits.
I've been no-stop researching and have come up with some more so interesting stuff, so yeah! :) I'll keep you posted.
 

blueroomelectronics

Well-Known Member
Gr3mlin2008 said:
Thats Exactly what im looking for! :)
But i want it to count backwards, like a real bomb would!

thanks for the replies guys! :)

It's all done in software, you can program it to count up, down, whatever.
 

Gr3mlin2008

New Member
I did some reading on that kit, its so you can light the DP's and it can divide the digits, also useful for Degree's display! :)
haha, sorry, straight from the hourses mouth!

wow, im so have no fun building this project so far!
I brought a few different things to help and they didnt really help. lol
i think i will look at it after a good nites rest! :)
 

blueroomelectronics

Well-Known Member
Like Gr2mlin2008 said, it's for an HH:MM.SS type display or temperature. The nice thing about 10pin displays is the common runs down the center pin. You can flip them and they work fine. dp & G are reversed but easy to compensate in software. If you don't want a clock building it with the decimal places along the bottom is fine like a frequency counter.
 

Gr3mlin2008

New Member
Ok, so i've been playing all weekend on this, having to wait for the shop to be open and all! So far what i have made, to my absolute self pride worked!
i decided to start from the very beginning, a bit of proto board and 3hours of solidering and i have a finished product.
At the moment i have made a 4bit binary counter, it counts upwards displaying its counting on 4 LED's, the principle is so simple its amazing! and it didnt confuse me like it use to, i've got it to count backwards aswell, sort of.
Atm it seems to count 9-8-7-8-7-6-5-4-3-2-1-0
then sometime is 9-8-7-8-7-8-7-8-7-8-7-8...
anyhow that not an issue, as long as its counting im happy!
Next, add another IC here, and transistor here, buzzer here
 

Gr3mlin2008

New Member
updates

well, an update, i've made a 2digit counter, it works great! and at 00 it stops dead in it tracks and latches and output open! :p
i started working on my next one, and again i find myself held up at adding a third digit, what happen's is it loads the inputs, and then i start the timer. 300 299 298.. see my problem, its not right.
im thinkning of going to a PIC, i buying my PIC programmer tomorrow.
what i've desided is to go with 4output for BCD and 4 output of Digit selection. (like a multiplexer)
any help with programing would really rock!
i also had a thought of 4 input BCD input, like 1100 = 3, this would be on digit 1, then 0111 to go to next digit, then 1010 = 5, on digit 2, ... you get the picture! lol
let me know if anyone can help! cheers.
 

RODALCO

Well-Known Member
decoupling caps

Have you decoupled all yor IC's ?

Put a 100 nF disc capacitor across all your IC power supply terminals.

A relatively large powersurge is created during output changes which can cause false triggering of the counters.

My $0.02 worth, Regards, Raymond
 

Gr3mlin2008

New Member
Have you decoupled all yor IC's ?
Put a 100 nF disc capacitor across all your IC power supply terminals.
A relatively large powersurge is created during output changes which can cause false triggering of the counters.
My $0.02 worth, Regards, Raymond

Yeap., its not that thats the problem. its that the BCD up/down counters cant be told that if that reach '0' then the next count will be 5 not 9 or with some BCD counters 15. i've worked a way to make this work with counting up! but not down. :S
i've also had a search for a 0-5 BCD UP/DOWN counter, with no luck.
If anyone does find or know of anything that would help please let me know! my friends are hanging out for this project as we can use it in our Airsoft Skirmishes
 
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