Circuit Specialists Inc.

[Orin Eman]

> What are you using for a voltage divider network on the O2 sensor?

I take the sensor into thru a 1Mohm resistor to the inputs of two
LM3914s.  For low pass filtering, I add a .1 uF cap to ground
after the resistor.  The LM3914 voltage dividers are connected
in series with a 499 ohm resistor in parallel with each to
minimise any variance between the two chips.  I drive the
dividers from one of the voltage refs via a 1k trimpot (actually
only 500 ohm trimpot is required, the value tends to be around 250 ohm).
The other voltage ref goes to a 2k trimpot to ground to set
the relative brightness of the LEDs between the two LM3914s.

Give it 5V, 20 LEDs and that's about it.

Orin.