help needed with led chaser

Thread Starter

martin.2010

Joined Nov 20, 2011
4
I have sorted out the shorts and resolder the bad joints the 555 timer don't get hot anymore but the still all the LED come on and stay
thanks for your!
 

SgtWookie

Joined Jul 17, 2007
22,220
Please take another photo of the bottom of your board; if you can, a bit better focused than the last one (you may have to be a bit further away to get a good focus).

In the picture you posted of the bottom in the first reply that bertus edited, it looks like there could be a break in the ground trace for the 1uF capacitor. This would make the 555 timer oscillate as fast as it possibly could, and it would look as if all of the LEDs were on constantly.

In the photo that bertus edited, the lower arrow is pointing almost right at what I think is a break. It is one hole down and one hole to the right of the hole nearest to the arrowhead. Try soldering a jumper over that break. You could use a piece of one of the LED leads that were left over.
 

SgtWookie

Joined Jul 17, 2007
22,220
Bill,
I believe the 555 is clocking so fast than Martin can't see the flashing of the individual LEDs. I don't know of another way that all of the LEDs would be all at once - unless he installed them all backwards and the LED anodes were connected to +9V instead of how they are supposed to be connected.
 

Wendy

Joined Mar 24, 2008
22,181
Like Martin, I generally use sockets on chips just because of the opps factor. The 4017 can be a sensitive chippie.

Martin, I have quite a few of those kind of circuits under my belt, even have my own article here I occasionally mention.

LEDs, 555s, Flashers, and Light Chasers

Also, take a look at the rest of the board, you may have other shorts.
 

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thatoneguy

Joined Feb 19, 2009
6,359
Use your meter in continuity mode, and go from IC pin to the neighbor and "tone out" the board to make sure you don't have unintentional shorts before applying power.
 

SgtWookie

Joined Jul 17, 2007
22,220
Here, I've also marked up the board you first posted.

All of the stuff circled in pink needs looking at.
The stuff circled in pink AND red are likely causes of the LEDs appearing to be staying on steady right now.
 

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Wendy

Joined Mar 24, 2008
22,181
This is a practice issue. Over time if you do this very often it gets much better.

Congrats on one of your first projects, it really does get better.
 
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