WB Display 17-15 & 13-11

[bcroe at juno.com]

The first shot at a universal bar graph display was
calculated out like this.  The thought was to use a
couple of green 10 segment parts and a couple of
10 segment red parts.  As designed, you could put
a 10 segment bar in to cover 10.89 to 12.98.  It would
only take about 6 segments to cover 15 to 17, due 
to the nonlinearity  of the F/A numbers.  Probably some
4 or 8 segment bars could be used to customize.

If we make a universal ckt bd, the first thought is to
display what the sensor can measure.  The numbers 
would stay spaced as shown, whether you actually 
put in an LED in a position or not.  The 2 center 10 
segment driver chips will be necessary; the outer 
ones are only needed if there are LEDS to drive. 

Part of the problem of having narrow windows, is any
inaccuracy in the measurement may put you off scale.
Like an 85mph speedo, off scale could mean 86 or it
could be 186.  Now that the calbration resistor feature
has been worked out, the system should be close.
But I'm hoping some of you with the necessary facilities
will do an accuracy check on the WB project.   

You may notice the F/A column, directly proportional to
fuel added, is linear over the entire range.  


LED      A/F        F/A     

GRN  10.00  .10000  
GRN  10.17  .09836                  
GRN  10.34  .09672                  
GRN  10.52  .09508                  
GRN  10.70  .09344                  
GRN  10.89  .09180                  
GRN  11.09  .09016                  
GRN  11.30  .08852                  
GRN  11.51  .08688                  
GRN  11.73  .08524                  
GRN  11.96  .08360                    
GRN  12.20  .08196                    
GRN  12.45  .08032                    
GRN  12.71  .07868                    
GRN  12.98  .07705                    
GRN  13.26  .07541                    
GRN  13.56  .07377                    
GRN  13.86  .07213                    
GRN  14.19  .07049                    
GRN  14.52  .06885 
RED  14.88  .06721      
RED  15.25  .06557                    
RED  15.64  .06393                    
RED  16.05  .06229                    
RED  16.49  .06065                    
RED  16.95  .05901                    
RED  17.43  .05737                    
RED  17.94  .05573                    
RED  18.49  .05409                    
RED  19.07  .05245                    
RED  19.68  .05081                  
RED  20.34  .04917                  
RED  21.04  .04753                  
RED  21.79  .04589                 
RED  22.55  .04425                  
RED  23.47  .04261        
RED  not used                                           
RED  not used                                            
RED  not used                                           
RED  not used                                            

The last 4 LEDs are not used, but could be hooked
up to things like power on, heater hot, etc.

I could easily see leaving off the bottom 10 LEDs
and driver, stopping at 19:1.  Just leave out the parts.
For custom scales, the 2 amps driving the rich and
lean sections could be customized for individuals.  
It is a matter of changing the gain and offset of the
driver amp.  

Bruce Roe
----------------------------------------------------------------------------
To unsubscribe from gmecm, send "unsubscribe gmecm" (without the quotes)
in the body of a message (not the subject) to majordomo at lists.diy-efi.org