DIY-WB02 display / Testing

[Chad Clendening]

Is the question about the circuit being more efficient or the test aparatus being better?

For testing:

I have some 13 ohm 250 watt Dale resistors I used for prototypes #1 and 2.  They worked very
well.
They are probably expensive - I don't know, found them on top of a trash bin a few jobs ago.

Otherwise, put the light bulb on a metal plate on your bench.

for the circuit -

Can it be done?

yes, a little more efficient BUT it would require a switching technique and complicate the
design.
The total power consumed would not be much less:

The UEGO heater needs about 11.5 volts to stay warm.
Typical battery voltage is 14 - 14.5 volts.


linear:       1.2 amps at 14.5 volts =  17.4 watts
switching  1.2 amps at 11.5   volts = 13.8 watts round to 14 watts for waste.

leaving a differance of 3.4 watts total dissipation.

These numbers are for an WB in free air.  Exhaust temps will aid the heater and cause less
current to flow.
One could substitute a FET for the bipolar output.  This would require modification of the V
/ I limiting circuitry.
The benefit would be limited to about a 0.3 volts lower requirement.

Chad

_________________________

Date: Sat, 09 Mar 2002 22:06:47 -0600
From: Tom Sharpe <twsharpe at mtco.com>
Subject: Re: DIY-WB02 display



> 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.

----- End of forwarded message from owner-diy_efi at diy-efi.org -----
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