buloi123

Please give me an schematic diagram of count down timer...
A count down timer with a hour:minute:seconds...
And also I can set the what time will I start to count down.

Thank you in advance.!

vincentdomingo_ph

i need also a countdown timer where i can increment time by about 5 minutes when needed. help us pls..

Nigel Goodwin

These applications are far easier done with a micro-controller than loads of logic chips - it comes down to one chip, a display, and the buttons. You have to program the chip, but it simplifies things so much!.

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cool-agent

use a 555 timer with a time delay

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buloi123

There's no software involve. Just a pure hardware...
Also, you can input on what time would you like to set....
Is this possible?

Nigel Goodwin

It's possible, but very involved - is this for a school project?, it's not a practical project except for the learning experience it would provide.

__________________
PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

buloi123

It's for actual project. I have to control the waterpump motor. The user can set the time the motor will activate, for example 6hours . At that time span, the user can also set another time where the motor will turn on, example 2hours, and also he can set the time the motor will stop or rest, example, 1hour... Based on the example, during six hours time span, the motor will turn ON for two hours, and turn OFF for 1 hour, then turn ON for two hours again then turn OFF for 1hour again until the six hour timer will elapsed... :roll:

Optikon

For an actual project, wouldnt you want it to be lowest cost possible and quickest/easiest way to a solution? I would take Nigel's advice and use a micro for this. And the finished product can be all hardware. Just because it takes some software to program the micro, this code can be downloaded and stored in a flash memory so that the unit runs stand-alone.

With all the setting flexibility involved, you really should consider a micro controller / PIC / CPLD or something so that you can write high level code.

If you MUST do this with logic gates, I would suggest using a dip switch to set the times in a binary format, you'll need an hour counter probably derived from a second-counter

and you should use flip-flops to make a state machine that will allow you to perform all your hour on / hour OFF antics.

This way will take a lot of time and debugging to work right and would arguably be more expensive in the end with all costs considered.