"John Fields" wrote in message
...
On Tue, 3 Apr 2007 22:32:55 +0100, "Wombat-Pipex-News"
wrote:


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.

---
Let's back up a minute.

The 3162 is an Analog to Digital converter, and if you're connecting
the pulses from your speedo directly to its analog input it won't
work. Is that what you're doing?

Well im connecting the speed sensor via 2 wires 1 to +12V then it goes
through the sensor to the LN2917N pin 1.
It goes to pin 1 via 10K Resistor, which is followed by a 22K pulldown, and
a .022uf Cap. which I think is to reduce and smooth the input.
All the diagram says is Frequency Input. Which acording to the blurb, is the
sensor.
Then the output from all that goes to the CA3162E. and also to a pair of
LM3914N`s which drive 20 LEDs in a bar graph.
Though even with this latest board that ive done its still unstable even
Without the sensor connected.
Now I've not tried cutting the track from LM2917N to isolate the CA3162E
(which is todays job. along with a new Volt Reg)

Though the first Board I did was NOT fed output data from the LM2917N as it
was a totaly different design. and used Common Cathode displays
But I did have the input from the speedsensor pigybacked to the LM2917N as
that was used for a bargraph part.
I now know that the inputs arnt compatible. as the LM2917N needs voltage to
go INTO it. but the other speedo had Voltage coming OUT. !
That then registered the drop in voltage to triger a counter. Now thinking
about it I should be able to do a work around.

This latest board was just laid out as the original diagrams showed, apart
from the 4511 replacing the 3162. which turned out to be more complex than I
thought.!
I have 2 speedo designs. I used the first design as I had most parts to
hand, but that was designed for a totaly different speed sensor, without any
bargraphs.
The second one and latest design was based on a Book I bought, for making
Speedos and fancey displays, this one uses Common Anode displays.
Though Im trying to make use of the first ones 7 segments and drivers.
Basicaly because I bought the CC.
Plus this one does Not have a dimmable display like my first one. That is
done by basicaly blinking the display via a blanking pulse. Very fast.
the CA3161E does not have a blanking pin like the CD4511 (Pin 4). which for
some reason does not work properly on this latest board !

Regards
Wombat.