"John Fields" wrote in message
...
On Tue, 3 Apr 2007 08:05:22 +0100, "Wombat-Pipex-News"
wrote:


Hi John... agian !! :-)
Ya I'd not mind a little diagram if you have one to hand, but only if you
have it to hand, dont go and spend hours making it just for me mate!
I already had that PDF But just missed that part on page 6 !! Now seing it
again I remember it. :-/ Tipical
I just figured that the ABCD was a streight 0123 connection like on the
CA3161. But didnt think to check first.
Right looks like it needs some pull Up resistors.
Am I right in thinking that I dont realy need those bits in the dotted
lined
area, as I don't want the display to show -99
or any over volts anyway. Which I think that part is meant to do. Its for
a
Speedo and Tach in a car, so it will only operate in a fixed range anyhow.

---
Right. you can get rid of everything in the dotted lines and also
the two diodes outside of the dotted lines. I don't know what those
black triangles are that connect to the 4012, but you can ignore
them as well.
---

As for the 7 Segment displays, I am using 3 singles like you described.
But
looking at the diagram it looks to have 3 buffers (CD4050B) instead.
Why.?

---
Dunno. Maybe another mistake?
---

I thought the CA3162E multiplexed the display anyhow using the PNPs.

---
It does, and for common cathode displays using a 7447, you'd hook
them up like this:


a----[LED]---+
|
b----[LED]---+
|
.
.
.
|
g----[LED]---+
|
E
FROM 3162----B PNP
C
|
GND

With the segments going to the 7447 through current limiting
resistors.

---

Also.. Is that an error on the PDF, Pins 2 and 7 are joined via x2 100k
Resistors and not used like pull-up resistors.?
I would have expected them to be wire up like pins 1 and 7 with a 100k Res
going to +V.
But looking at the diagram pin 2 is direct to +V. Did they cock up and
put
the BLOB (wire joint) on the wrong line.?

---
Yeah. The joint ought to connect the two 100k resistors to V+, and
3162-15 ought to go to 4511-2



--
JF

Well a quick update on whats happened so far.
I wired it up just as it showed on the diagram, Including the possible
mistakes.!!
First off I tried it with just the pullups but it didnt work. Just stayed
Black.
Then I removed them.
Tried the Buffers ( Used a 74HC14N instead of the 4050) with the pullup
resistors. That then replaced the NPNs.
It did actualy work !! although I only used 3 buffers and not 6 like it said
too. But.. It just displayed 444.
So I added the original pullups again, and bingo it all lit up but with a
major glitch. !
The display just flashes random numbers. over volts under volts, display
going on and off. very bizzare effect.
Now either I've got a serious power instability problem (Possible) or the
wireing diagram is wrong !! Possible
I say its possible, because the same problem happened with my other speedo
design. Though that only got random when the speed sensor was active.
When the display was just on, with out any pulses, it was dead steady. At
first I though it was a design fault of that original diagram. But now Im
starting to think otherwise.
That design was only meant to uses 2 pulses per rotation, but the speed
sensor give 6. I just figured it would show more faster. I contacted the
guy who originaly designed the board, and he said a possible power
instability problem. I though otherwise !! hence the total re-design.
I prefer the 4511 to the 3161 as its got the dimmable display option. which
worked on the other board, but not with this one. :-/

I think im going to break this down into a much more controlled manner
first. Then I can correct the stability faults on Both the designs to have
the best of both worlds.
At the moment Ive got lots of other IC sharing the +V and GNDs which could
be causing the problems.
I though I could get around it by having separet Volt Regs, for different
parts, but that didnt work. they all take the voltage from the same source.
Plus they all share the same GNDs. I guess this is where im supposed to
use -Volts and complex supressors !
Or
Make **** loads of sepate boards !! :-)

Well the boards both look grovey and complex but so far fail to work
properly. both do 90% of the job. but are both let down by the main bit. the
speedo. :-/
Though the odomiter worked OK im pleased to say. so that shows the speed
sensor and counting circuits are fine.

I guess its, Back to the drawing board....... Again.!!

Regards
Wombat.