O2 sensor meters

[Orin Eman <orin@wolfenet.com>]

For those that have asked about these, there is now a picture of the new
design on:

http://www.wolfenet.com/~orin/o2meter1.jpg

The displays could be mounted on the back of the board if desired,
but they stand well clear of the other components.

It has 10 red LEDs for lean and 10 green LEDs for rich.
You could mount discrete LEDs instead and use whatever
colors you like.  I'm not going to do remote displays this
time - the new board isn't much different in size to the
old remote board.  It's approx 1.5 x 2.5".

Note that it's really only a volt meter that reads 0 to 1V,
so you could use it for other things, for example
battery voltage or a boost meter if you use an appropriate
voltage divider on the input.

The on-board trimpots control the full scale reading - it
will go up to about 1.2V, the limit of the LM3914 chips
and the relative brightness of the displays - the brightness
of the green LEDs can't be changed.

Current 'features' (MS for bugs):

It would be nice if both displays had the same background color.
No pretty box - in fact, no box at all.
It's 2.5" wide... getting it down to 2" so is a challenge,
so don't count on there being one available that will fit in
a 2" guage in the near future.

If anyone wants more information, let me know.  If you are
interested in the chips used, look up LM3914 on www.national.com.
The schematic is available for appropriate bribes (beer/latte).

Information on the companion duty cycle meter is to follow
once I get a picture taken of it.

Orin.