How to plug a LED ?

[The Smith]

Oh...A luck I asked...

 

And on the circuit, black dots between lines represent intersections, and when there is no dot where lines cross, I guess they should not touch ?

[markiemrboo]

Oh...A luck I asked...

 

And on the circuit, black dots between lines represent intersections, and when there is no dot where lines cross, I guess they should not touch ?

 

That's right

[The Smith]

And I will put only 6 LEDs for the moment. Can I plug them on any Q0-Q9, or there is specific pins I should let unused ? And will they flash at regular intervals or or there will be "holes" in the flashing ?

[markiemrboo]

And I will put only 6 LEDs for the moment. Can I plug them on any Q0-Q9, or there is specific pins I should let unused ? And will they flash at regular intervals or or there will be "holes" in the flashing ?

 

It should count from Q0 to Q9 sequentially. There will be a gaps if you don't fill it with 10 LEDs. For testing I would just put them in starting from Q0.

[The Smith]

Hey,

 

The circuit construction is going very well. I decided to plug the LEDs on 5V, as you explained. But can they use the same Gnd as the 12V part with the ICs ?

 

Edit:And why are the pin not in order with the QXs ?

Edited March 16, 2008 by The Smith

[markiemrboo]

Hey,

 

The circuit construction is going very well. I decided to plug the LEDs on 5V, as you explained. But can they use the same Gnd as the 12V part with the ICs ?

 

Good to hear. It should be fine to use the same ground.

 

edit - The pins are up to the IC designer. I guess it was a design constraint / choice.

Edited March 16, 2008 by markiemrboo

[The Smith]

Hi,

 

bad news this time... I finished to build the circuit, but it doesn't work...

 

I tried to figure out why.

 

1st: There's only one pink LED that is always on, and it is not flashing. When playing with VRs, I got 3. Can it be that this VR idea doesn't work and I should use normal resistors instead ?

 

2nd: Are you sure both 5V and 12V parts can use the same ground ? Because if the ground is the negative(I think), the electrons in the wire are flowing from negative to positive, that is to say the inverse way of the current convention, which is the movement of the positive charges. So I'm not sure it's working, but if you say yes, you are probably right, I trust you...

 

Here's some pictures of my circuit: (Yes I know that I used 1/4 of the whole board and I could have used all the room, but this way I have room left for future circuits.)

[markiemrboo]

Hi,

 

bad news this time... I finished to build the circuit, but it doesn't work...

 

I tried to figure out why.

 

1st: There's only one pink LED that is always on, and it is not flashing. When playing with VRs, I got 3. Can it be that this VR idea doesn't work and I should use normal resistors instead ?

 

2nd: Are you sure both 5V and 12V parts can use the same ground ? Because if the ground is the negative(I think), the electrons in the wire are flowing from negative to positive, that is to say the inverse way of the current convention, which is the movement of the positive charges. So I'm not sure it's working, but if you say yes, you are probably right, I trust you...

 

Here's some pictures of my circuit: (Yes I know that I used 1/4 of the whole board and I could have used all the room, but this way I have room left for future circuits.)

 

Hi,

 

It sounds like the 555 isn't oscillating as it should, or perhaps at a much slower frequency. It is, unfortunately, hard to tell what's wrong from the pictures of your circuit. A potential source of error would be the VRs. Have you simply replaced the charge / discharge resistors, R1 and R2, with VRs, and connected the wiper (the middle pin) to either end (either of the two remaining outer pins)? What value did you use? 10k? If so, set them both to 10k and make sure they are wired properly.

 

And yes, the 5v and 12v can use the same ground. If you open your power supply, both the 5v and 12v rail will share the same ground anyway.

[The Smith]

I replaced charge discharge capacitors as you said on the first page of the thread:

 

You may want to include variable resistors to tweak the time. I don't recommend you simply replace R1 and R2 with variable resistors. You should leave R1 and R2 but reduce their value (~680R to 1k ish), then add a higher value (~100k) variable resistor in series with each resistor. So one VR between 12v and R2, and the other between pin 7 of the 555 and R1.

 

I used 1K resistors and 100K VRs...Uh-Oh... Is this the error ? Was it supposed to be 10K instead of 100K ?

 

Besides that, I re-check my connections for the Xth time and we'll see...

 

Edit: I knew the pictures wouldn't tell you nothing, I just send them to show you my work after learnig how to solder...And I used this freshly-learned skill to make my vdroop mod lol

Edited April 11, 2008 by The Smith

[markiemrboo]

I replaced charge discharge capacitors as you said on the first page of the thread:

 

 

 

I used 1K resistors and 100K VRs...Uh-Oh... Is this the error ? Was it supposed to be 10K instead of 100K ?

 

Besides that, I re-check my connections for the Xth time and we'll see...

 

Edit: I knew the pictures wouldn't tell you nothing, I just send them to show you my work after learnig how to solder...And I used this freshly-learned skill to make my vdroop mod lol

 

Ok cool. The value of the VR shouldn't matter too much, so don't worry about that. Could you confirm that they are connected like the following:

 

 

If you have a multimeter then it could be useful to check a few things. Set to voltage measurement, DC, and put the black probe to ground.

 

With the circuit powered.

 

Red probe to pin 4 of the 555, this should read 0v.

Red probe to pin 8 of the 555, this should read 12v.

Red probe to pin 1 of the 555, this should read 0v.

Red probe to pin 15 of the 4017, this should read 0v.

Red probe to pin 13 of the 4017, this should read 12v.

Red probe to pin 16 of the 4017, this should read 12v.

Red probe to pin 8 of the 4017, this should read 0v.

Red probe at either pin 3 of the 555 or pin 14 of the 4017, set the VRs both to 100k. You should see the voltage reading spike up to 12v and then back down again over and over.

Red probe at pin 7 of the 555, VRs set both to 100k. You should see the voltage slowly climb and then suddenly fall to 0v over and over.

Red probe at pin 6 or 2 of the 555, VRs set both to 100k. The voltage should slowly climb and then slowly fall, but not necessarily to 0v. This should repeat over and over.

 

 

With the circuit off, set the multimeter to measure continuity, or if it doesn't have this feature, resistance.

 

Measure between pin 3 of the 555 and pin 14 of the 4017. It should beep or read close to 0, or both.

Measure between pin 2 of the 555 and pin 6 of the 555. It should beep or read close to 0, or both.

 

 

You could also try a 100nF cap (if you have one spare) between pin 5 of the 555 and ground.

[The Smith]

Ok...I found the problem. Thanks for the schematic.

 

I used this website to know how to plug the VRs http://www.kpsec.freeuk.com/components/vres.htm , and I used them as a rheostat, connecting only the wiper and one pin.

 

I now see that you mentioned it at the end of page 3 but I was so sure about my VRs connections that I simply didn't think that it was what you meant, and understood that the wiper and another pin should both be conencted to the circuit.

 

Now that I saw the small picture of it in the schematic, I know that I need to use it as a preset, as it is showed on the website. So I'll fix this problem and if I still have some, I'll check what you said with my multimeter(Yes, it has the continuity function).

 

I'll tell you if everything is ok, and I'll post pictures of my case very soon !

[markiemrboo]

Ok...I found the problem. Thanks for the schematic.

 

I used this website to know how to plug the VRs http://www.kpsec.freeuk.com/components/vres.htm , and I used them as a rheostat, connecting only the wiper and one pin.

 

I now see that you mentioned it at the end of page 3 but I was so sure about my VRs connections that I simply didn't think that it was what you meant, and understood that the wiper and another pin should both be conencted to the circuit.

 

Now that I saw the small picture of it in the schematic, I know that I need to use it as a preset, as it is showed on the website. So I'll fix this problem and if I still have some, I'll check what you said with my multimeter(Yes, it has the continuity function).

 

I'll tell you if everything is ok, and I'll post pictures of my case very soon !

 

So long as the wiper is connected to something it should be OK. If you connect the wiper to the "free" pin, if the wiper momentarily comes off of the track when adjusting it, it will still act as a fixed resistor (in this case of 100k), rather than momentarily going open circuit. It probably wouldn't matter too much in this circuit if it was just the wiper and either side connected.

 

Doing those quick checks might show something hopefully. Make sure the circuit doesn't have power when checking continuity.

 

Looking forward to some pictures when we get it working!