DIY-WB02 display

rr RRauscher at nni.com
Thu Mar 14 13:31:32 GMT 2002


The light bulb test is not the best. To simulate a cold sensor
use a 3 to 4 ohm 5 W resistor. You will need to keep the
duration short. A cold sensor only stays cold for about 10
seconds. Within 45  seconds it will be > 700 deg C.

Use the 3-4 ohm to measure the max current limit and then
power the circuit down. The max current should be ~ 1.5A.

Then switch to a 10 ohm 5 W resistor. With this resistor the
circuit will voltage limit at 10.4 to 10.5 volts. The current will
typically be ~1.05A.

In this mode the circuit may be left powered up indefinitely.
The resistor will get hot, so be careful. A hot NGK WB sensor
runs about 9.8 to 10.4 ohms. The resistance of a cold NGK
WB sensor is about 3.3 ohms at room temperature.

Note that the above tests are for the DIY-WB heater control
circuit.

BobR.


Tom Sharpe wrote:

> rr wrote:
>
> > The UEGO controller portion of the circuit will run on
> > voltage as low as 11 volts. It also draws < 25 mA, just
> > don't quote me on that number. I don't have my notes in
> > front of me.
> >
> > It is the heater circuit that requires the minimum of 13
> > volts @ ~ 1A.
> >
> > BobR.
>
> For all you lurkers, rr always has the straight scoop.  Question for Bob, (I'm
> not a EE), Ive been testing w/ a light bulb. This thing sure gets hot and beats
> the he#$!@%#$ out of my battery charger which will light the bulb easily. Could
> someone design a more efficient circuit or is something wrong????  TomS.
>

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