On Thu, 30 Nov 2006 17:43:41 -0500, "Wombat-Pipex-News"
wrote:


"John Fields" wrote in message
...

Just ran that program and printed out the diagram.
I tried to run the thing, but it didnt make any sence to me.
Just lots of coloured lines!!

---
The lines are what the voltages would look like where you point the
probe if you had a storage oscilloscope. The X axis is time; in
this case 10 seconds and the Y axis is voltage.

So, if you left-click the probe on the collector of Q1 you will see
when it turns on and when it turns off.

Similarly for the collectors of Q2 and Q3.

If you get too many traces on there and thing get confusing, just
double click the circuit node you're interested in and all the other
traces will go away.
---

from first looking at the alts you seem to have just added 3 caps and 3 more
pulldown resistors.

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Yes.
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Why does the gates look different.? Have you used a different chip.?

---
No, that's just LTSPICE's way of letting you have a component which
you can use with either a lot or a few inputs. The way they're
being used is as 2-input NORs, same as before.
---

Why did you add the 3 extra puldowns.?

---
Those are DC returns for the caps. That is, it allows them to
discharge when the latch toggles and get ready for next time.

Try it. That is, take them out (R13, 14, and 15) and you'll see
that as the LEDs turn on, one at a time, the others never turn off!
---

does that part just get double up on
the other 3.? pin 6 pin 12 pin 3 all already have puldowns resistors after
the diodes.

---
Yes
---

Am I right in thinking that all I have to do is cut the 3 tracks and add a
Cap. to cure the fault.?

---
No, you need to cut the tracks and solder in the caps across the
cuts, then you need to add R13, 14, and 15 from the side of the cap
not connected to the latch, to ground.
---

If so what type.?

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Not critical. 0.01 to 0.1µF ceramics should be fine.
---

Hopefully its a quick fix. :-)

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Should be, it's just make three cuts and add 3 parts.
---

Thanks for the help John.

---
You're welcome. Sorry about the error(s) :-(

BTW, just in case you were wondering, V1, V3, and V4 are voltage
sources being used as the switches cycling sequentially and
endlessly, and the reason D7 doesn't come on on power up is that V4
is shorting the power-on spike to ground. That wont happen in real
life.

Also, I've used diodes instead of LEDs, but the current limiting
resistors were chosen for about 20mA into an LED with a 1.2V drop.

YMMV, so you may want to recalculate those resistors for the LEDs
you're using:


Vcc - Vled
Rs = ------------
Iled



--
JF