Circuit Specialists Inc.

[Orin Eman]

> Circuit Specialists' units are not backlit.  Digikey has both types,
> backlit being more expensive, non-backlit still much, much more than
> Circuit Specialists.

Actually, that's typical.  I got a backlit 16x1 LCD display locally
for $8 (surplus), >$40 at DigiKey... same part!

> >
> I'd check how frequently the meter updates.  Usually it's only a couple
> of times a second.  You would want a low pass filter with a cutoff of
> around 1Hz before the meter to produce sensible results!  You can see
> the O2 signal swing back and forth on LED type displays - if that's what
> you want of course.<
> The Circuit Specialists unit is 2 - 3 times per second, same as the others.
> I can add a low pass filter if needed but it may not be.  Last summer I
> used my DVM directly to read the output of the O2 sensor without any
> problem. The typical LED unit has a resolution of 0.1 volts while I was
> using my DVM set to 0.01 resolution.  I found that extra decimal point of
> resolution to be very helpful. I used it to set the jetting of the new
> carbs on my motorcycle and it was MUCH better than doing plug chops. I am

In your case, the reading isn't going to be fluctuating like the
closed loop systems, so I'd guess you wouldn't want any filtering.

Orin.