[Wbo2] Can't get up and running

[bcroe at juno.com]

Make sure your supply near 14 volts.  When you turn on 
power, you should immediately see 1.25 volts across 
R4, the big 1 ohm.  This should remain steady while 
the voltage to the heater (J1 to J2) slowly rises from 
about 4 volts to about 10.2 volts.  At that point the 10.2 
volts should stabilize, the LED should come on, and 
the voltage across R4 should eventually decrease at 
least 10%.  If it doesn't decrease enough, add 2 or 3 
15 ohm 1/4 watt resistors in parallel with R4.  

You need the anti oscillation cap to stabilize the circuit.  
That is a 0.01 to 0.1 ufd ceramic added across pins 
1 and 3 of D5.  There are a few other things that can 
be done to improve the dynamic response of the unit, 
which tends to overshoot.   Bruce Roe

> > --- Russ Hildebrand <russellh911 at comcast.net> wrote:

> > > I'm working on this on the bench with a 12 volt
> > > power supply, not in the car. I had this all in the car 
> > > and it didn't work, so I took it back out this 
> > > morning and I've been messing with it. I've
> > > only had 12.6 volts supplied at the max at any 
> > > on time, so that might be the fundamental problem. 
> > > With my test bench power supply, I start with 12.6 
> > > without the sensor, but when I attach the sensor the 
> > > voltage drops.