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Buidling own WBO2 
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TO220 - Visibile

Joined: Mon Nov 21, 2011 11:20 am
Posts: 6
Simply, I need to build own WBO2 in short time.
My engines really wanna be tuned for spring.

I would appreciate any help.
If someone knows valuable websites or has his own materials contains:
-(free) description of complete project
-algorithms / source code
-analog part circuit diagrams
-graphs and datesheets of sensors

I plan to build round sensor with LED display and also RS232/485 bus for datalogging/communication/future development.
I would use AVR Atmega(8) CPU.

Sorry for giving so primitive requests, but I have a lot of work, little time and I would not want to do something that someone has already done, in addition worse than him.


Sat Mar 16, 2013 1:51 pm
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LQFP144 - On Top Of The Game
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Joined: Tue Mar 02, 2010 2:33 pm
Posts: 1201
Location: Australia
To build a wbo2 from scratch is no simple quick feat!

Might I suggest grabbing a cheap module from www.14point7.com as I feel it would be quicker, unless certain people feel like assisting you, which they might, who knows.

A lot of people are really busy on these forums, but hopefully someone with experience in this field will help you out.

Be sure to let us know what you come up with :-)

Good luck!


Mon Mar 18, 2013 1:25 pm
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TO220 - Visibile

Joined: Mon Nov 21, 2011 11:20 am
Posts: 6
I'm a little disgusted by the suggestion: "Do not try to build" :)

First, if there is someone, who built (in the sense of designing and writing software) that the O2 sensor?
I have two Delphi WBO2 sensors, very cheap ($ 30/pc), supposedly compatible with LSU4.

Browse project at http://www.waltech.com/. Anyone likes this project?

He published the principle of operation, definitely useful, and probably enough to build a complete unit:
http://www.waltech.com/site/index.php/o ... ler-design
Does anyone believe that any important function is missing from his list?

I would like to build a complete index of the display, so I guess redesign PCB, so also write the firmware again.

Does anyone know of a communication standard that should use to be compatible with used standard?
Do FreeEMS now supports WBO2, directly or remotely (via digital interface)?
What communication interface? RS232/RS485 / something else?


Tue Mar 19, 2013 5:37 am
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Wideband Wizard

Joined: Tue Jun 10, 2008 2:53 am
Posts: 241
Location: Toronto Canada
Check the June 2012 issue of Silicon Chip magazine, they have a wideband controller project in there. I am not sure if the source code is available, if it is not then it is not a big issue as the source code is mostly 2 PID controllers (one for pump cell and one for heater control) the important part of that article is that it is full of good information about wideband sensors and the basic approach to control them. The author of the article managed a small miracle stuffing as much information as he has in only 6 pages.

The circuit design is quite solid, I would have gotten rid of -ve voltage supply and the 12v regulator for the op amp that drives the pump cell and would have not bothered with the IC4a opamp.

I am not a fan of the waltech schematic, it needs to include; amplifier on the feedback signal, anti aliasing filters at the very least, resistor between FET gate and uC pin to minimize voltage reflections, R10 should be 10k and not 6.8k.

I would trim the Silicon Chip design rather than add to the waltech design.

It is not hard to come up with a wideband design, the problem is dealing with noise and with being accurate after you have layered on so many op amps and 1% resistors. The waltech design would get raped by noise and it creates a huge amount of noise by not including a resistor between the FET gate and the uC pin. Both designs rely on a op amp in differential configuration with 1% resistors which introduces non linear errors due to finite input impedance and linear errors due to resistor mismatch.

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Tue Mar 19, 2013 9:59 pm
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LQFP112 - Up with the play

Joined: Tue May 01, 2012 4:17 pm
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cucumber wrote:
Does anyone know of a communication standard that should use to be compatible with used standard?
Do FreeEMS now supports WBO2, directly or remotely (via digital interface)?
What communication interface? RS232/RS485 / something else?


FreeEMS supports passing WBO2 straight through as an analog input to the datalog. You pass it 0-5V, and that reads as X-Y lambda. Not sure those exact values, it would depend on the controller. There's no reason to introduce the lag of a serial communications protocol when FreeEMS can read analog voltages directly.

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Tue Mar 19, 2013 11:36 pm
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There is a point in doing it digitally, as you eliminate DAC > ADC issues and ground level issues. There are threads for both Alan's SLC stuff and the LC1 floating around. ADC input is just easy, that's all :-)

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Wed Mar 20, 2013 8:30 am
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TO220 - Visibile

Joined: Mon Nov 21, 2011 11:20 am
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Someone could scan and send me an article from Silicon Chip? I don't want to buy subscription to view one article, not even having the intention to build a device described herein.
I understand if you refuse, but please understand that I do not live in the U.S. and I can't just go to the library and read.


Thu Mar 21, 2013 10:12 pm
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LQFP112 - Up with the play

Joined: Wed Aug 28, 2013 6:07 am
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I looked into this and came across a lot of articles that say " use a digital multi-meter and compare output voltage to this table (included) OR build this $45 kit on a breadboard and stuff into this enclosure and read off this lcd readout..." if you are only reading the output of the EGO in volts, could you not just use an analog 0-5v gauge and sharpie in the AFR values under the numerals on the gauge face? Or does the controller monitor EGO temps and voltage? Just an observation, school me if i'm being a simpleton. :-)


Tue Sep 10, 2013 1:29 am
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You're being a simpleton :-) Check Hell_Fire's thread on his setup, there is some clarification discussion in there.

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Tue Sep 10, 2013 9:32 am
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