timer help!

[sword]

i'm designing a steady-hand toy for my GCSE electronics project with a built in timer

is/are there chip/s (perferably common) thats allow me to achieve a count down timer and to trigger on output when 00sec is reached

i've heard of the 4029 but don't know much about it

thanks for your help

 

[jrz126]

what about a 555 running at 1 Hz. it's output connected to the clock of the 4029. then have the 4029 set to count down, when it reaches 0 the carry input will be brought high (looking at the logic waveforms, it's only brought high for 1 clock cycle, so you'll have to tell it to shut down somehow.)

4 dpst dipswitches could be used to set the timer, they would be connected to the jam inputs and another pushbutton would be connected to the presetset enable pin. So whenever you push the button, it takes whatever the dipswitches are set to (high or low) and loads that into the counter.

This will give you a total of 16 seconds.

here's the datasheet that I refered to:
**broken link removed**

I cant wait until I'm assigned some real problems like this in my classes.

 

[sword]

i'm real sorry but coz i'm a newbie i've had trouble understanding most of what you said like with the DPST switches and how all that works.

if you don't mind, could you please show me how this would be set up, i would be real grateful

thanks

or if anyone else can help, time and effort much appreicated

 

[-=GST=- Nemisis (cs/cz)]

use a pic ffs, if ur doing gcse like me u should be fimiliar with pics and a program called pic logicator. use that with the time on the comparison block and then have it count however long then use the outputs to do or trigger whatever you need. this will shoud u can use outputs, inputs and pic logicator.

 

[sword]

i know i can use pics, but i need to understnad the full circuit first, and i am having trouble understanding how the 4029 is connected.

if you can, could you explain to me how that is connected

thanks

 

[-=GST=- Nemisis (cs/cz)]

isnt a 4029 a bcd counter/decoder chip? just search for 4029 electronics on agoogle u will probably get a datasheet.

 

[sword]

OK, thanks for help everyone but just need help clearing up a few things about the 4029,

what are the Jam inputs and what are the Q pins?

which pin would the input from the 555 come into?

can i cascade with this chip and if i can, how?

which pin leads to the 4511?

how do i trigger an output with this chip when the timer has reached 00

thanks

 

[sword]

can anyone help me?!

 

[sword]

ok, i solved some of those puzzles i was having before
i just need to know now how to trigger an output when the timer reaches 00.

 

[williB]

ok, i solved some of those puzzles i was having before
i just need to know now how to trigger an output when the timer reaches 00.

https://www.electro-tech-online.com/custompdfs/2004/10/CD4029BCPDF.pdf

use the carry out ..it goes low when the count reaches zero..
in binary mode anyway..

 

[sword]

thanks WillieB and everyone else