timer to count pulse every 60 seconds

[ieda]

hi!!

i hv some problems with my project, about heart beat monitoring system..
here is my project's flow....

decade counter(7490) ---->binary to 7 seg decoder(7447A) --->7 seg display

my questions are,

1) how i'm going to make the counter to reset EVERY 60 seconds??? I plan to use 555 timer for my cct

2) how i'm going to make the alarm (buzzer) to activate when it over the limit..eg. i want to display the no. on 7 segmant below 100.... and if it display over 100, the alarm will activate...i want to know the connection..

can someone help me, maybe with the schematics and anything,,, PLEASE HELP ME...

ps: i. not using PIC coz i hv prob with the coding part

email:ieda_teruchan@yahoo.com

 

[Ubergeek63]

you would need another counter and a time base unless you thing an RC is accurate enough for you.

Dan

 

[Hayato]

Why did you wrote your email? Do you want us to send you the schematic?

 

[Ubergeek63]

hi!!

i hv some problems with my project, about heart beat monitoring system..
here is my project's flow....

decade counter(7490) ---->binary to 7 seg decoder(7447A) --->7 seg display

my questions are,

1) how i'm going to make the counter to reset EVERY 60 seconds??? I plan to use 555 timer for my cct

2) how i'm going to make the alarm (buzzer) to activate when it over the limit..eg. i want to display the no. on 7 segmant below 100.... and if it display over 100, the alarm will activate...i want to know the connection..

can someone help me, maybe with the schematics and anything,,, PLEASE HELP ME...

ps: i. not using PIC coz i hv prob with the coding part

email:ieda_teruchan@yahoo.com

On #2 it would be easier to use a universal counter, preload and count down.

 

[Hayato]

Use a %60 counter in parallel with a heart beat counter.

 

[ieda]

Why did you wrote your email? Do you want us to send you the schematic?

no...ah..dun know how to explain...

by the way...can u guys explain it in simple way...

about reset the counter every 60 seconds, someone told me to connect 555 timer output to EVERY pin 2 and 3 of 7490 counter. In my case i will use 3 decade counter to display till 3 digits.... and about the alarm, he/she told me tu use magnitude comparator (P>Q)...

what u guys think.???..i'm still working on it....try my best to understand it better....

sorry for my poor eng...

 

[Hayato]

You wont need a 555 timer in each pin 2.

7490 is not the best counter to combine. Use a 74160 instead, it'll be much more elegant. That's because, 7490 does not have an enable funcion. You'll wont be able to make it stop counting, unless you suspend its clock.

The only diselegant option in this case is to do a ripple counter, but you'll cascade the delays, but in this case, you'll use 2x7490.

The first one, will have the 1second clock, from 555.
You'll need a logic array, to output a high level, when the first counter comes to 1001 (dec 9), (a 4 input AND gate with 2 inverters would be nice).

The AND gate output will be the second 7490 clock. Then you'll need another logic array to reset the second counter when it comes to "6" (0110). Well, the datasheet does not state if the counter has a synchronous or asynchronous reset logic. If it is asynchronous, then "6" is fine.
If it's synchronous, you'll have to reset it when the first comes to "9" and second to "5", otherwise you'll have 1 second delays.

I believe it's asynchronous.

 

[3v0]

ieda,

ps: i. not using PIC coz i hv prob with the coding part

I see a challange for you here.

The longer you put off learning to program (well) the longer you will be handicaped.

3v0

 

[ieda]

ieda,



I see a challange for you here.

The longer you put off learning to program (well) the longer you will be handicaped.

3v0

hehe!!
actually i'm trying to do 2 methods... this one and the other one i use PIC..same projects with different methods....i also want to learn programming coz i know how important it is....thats why...just in case one of my project not working...at least i hv another one...

 

[3v0]

hehe!!
actually i'm trying to do 2 methods... this one and the other one i use PIC..same projects with different methods....i also want to learn programming coz i know how important it is....thats why...just in case one of my project not working...at least i hv another one...

Sounds like a plan. Just make sure you can finish at least one on time.