JF

On 2008-10-28, John Fields wrote:

JF

Rev A.

JF

On 30 Oct 2008 09:10:02 GMT, Jasen Betts wrote:

On 2008-10-28, John Fields wrote:

JF

begin 644 20 led chaser.pdf

this'd work too right?

---
Looks like. Clever! :-)

JF

On 2008-10-30, Jasen Betts wrote:

"Jasen Betts" wrote in message
...
On 2008-10-30, Jasen Betts wrote:

begin 664 LED chaser.pdf

Now with more drive.
enjoy.

Hi Jasen. Well, I have built that circuit and what I've ended up with is a
rather elaborate LED flasher :-) That is, all 20 LEDs flash in sync at a
rate of about twice every second. Any ideas?

IanW


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On 2008-11-06, IanW wrote:

"Jasen Betts" wrote in message
...
On 2008-10-30, Jasen Betts wrote:

begin 664 LED chaser.pdf

Now with more drive.
enjoy.

Hi Jasen. Well, I have built that circuit and what I've ended up with is a
rather elaborate LED flasher :-) That is, all 20 LEDs flash in sync at a
rate of about twice every second. Any ideas?

the speed seems about right :-) not sure what's wrong though.

all 20 are on at the same time ?

or is it 10 on then the other 10 on?

you may want to slow it down so you can see what it's doing better
increase R1 or C1 (doubling one of them halves the rate etc)

it could be power-supply bourne noise, try puttin 100nF capacitors from
pin 16 to pin 8 of the 4017 and from pin 14 to pin 7 of the 4047


if that doesn't help (if they unplug) pull out the 4017 and put a jumper
from the socket for pin 16 to the socket for pin 11

that should make only 2 of the leds work if it doesn't there's a
wiring problem somewhere between the 4017 and the transistors.

if it does it's possible the 4017 has bee damaged.


if all 20 are on at the same time there's something wrong with the 4047
else it's working correctly.


Bye.
Jasen

"Jasen Betts" wrote in message
...

all 20 are on at the same time ?

Yes they were, but...

or is it 10 on then the other 10 on?

... now it's yes to this question - see below

you may want to slow it down so you can see what it's doing better
increase R1 or C1 (doubling one of them halves the rate etc)

it could be power-supply bourne noise, try puttin 100nF capacitors from
pin 16 to pin 8 of the 4017 and from pin 14 to pin 7 of the 4047

if that doesn't help (if they unplug) pull out the 4017 and put a jumper
from the socket for pin 16 to the socket for pin 11

I increased C1 to 470nF which slowed things down a bit, then took the 4017
out and wired up that jumper and exactly the same problem - all 20 flashing
on/off at the same time. In fact even without the jumper!

However, I found that I had wired R11 from the base of Q11 down to pin 11 of
the 4047 instead of pin 10. So now 10 flash on simultaneously, then off,
then the other 10 flash on/off.

hehe progress!

that should make only 2 of the leds work if it doesn't there's a
wiring problem somewhere between the 4017 and the transistors.

if it does it's possible the 4017 has bee damaged.

Nope it stays as 10 on 10 off, not just 2 LEDs. Rest of the wiring seems
fine.

Well, this is the nearest I've got to chasing anyway

Thanks
IanW


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On 2008-11-08, IanW wrote:
"Jasen Betts" wrote in message
...

I increased C1 to 470nF which slowed things down a bit, then took the 4017
out and wired up that jumper and exactly the same problem - all 20 flashing
on/off at the same time. In fact even without the jumper!

my guess is you've got some of the transistors round the wrong way.

However, I found that I had wired R11 from the base of Q11 down to pin 11 of
the 4047 instead of pin 10. So now 10 flash on simultaneously, then off,
then the other 10 flash on/off.

hehe progress!

cool!

that should make only 2 of the leds work if it doesn't there's a
wiring problem somewhere between the 4017 and the transistors.

if it does it's possible the 4017 has bee damaged.

Nope it stays as 10 on 10 off, not just 2 LEDs. Rest of the wiring seems
fine.

the 10 led-pair transistors (Q1 to Q10) should be off with the 4017 removed
so there's something wrong there. as they are conductiong with no base
current present. tripple check them.

Try removing Q1 that should make two of the leds stop lighting up,
if not there's a short circuit on your board. if it does there's
something wrong with Q1, (wrong way round, or damaged, or both)

my guess is you've got the base and collector swapped, if that's the
case it won't have damaged the transistors.

when you get it the right way round a jumper from pin 3 to 14 of the
4017 socket will control the first 2 leds,

when you fix that problem then do the same to the other transistors and
then plug the 4017 back in.

Well, this is the nearest I've got to chasing anyway

double cool! stay happy!

Jasen