Need help with an LED countdown

Thread Starter

Lost_Thought

Joined May 13, 2007
2
I am new to electronic device making and i was wondering if there is a simple way to modify this project to start with all 10 LEDs on and sequentially turn them off. I can think of several ways to do this mechanicly but i would prefer the more robust and elegant solution of an all electronic device. Any advice would be great!
 

hgmjr

Joined Jan 28, 2005
9,029
I think all you would need to do is turn the LEDs around and connect the resistors to the positive supply bus instead of ground.

hgmjr
 

recca02

Joined Apr 2, 2007
1,214
well from circuit it wasnt very much clear to me and i didnt read the wole page,
so is it the case that all lights glow at once and then one by one they turn off?
i believe this can be done with the help of a shift register,lets see what others say.
 

hgmjr

Joined Jan 28, 2005
9,029
If you are looking for the LEDs to sequence right to left rather than left to right all you would need to do is reverse the order of connection between the 4017 and the LED array.

hgmjr
 

recca02

Joined Apr 2, 2007
1,214
i think giving a data input of logic '1' constant to a 10 bit shift register
serial in parallel out and connecting led in such a way that they glow when o/p of respective register is low (perhaps like mr Hgmjr said).
this i believe shud work.
 
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