Re:diy af meter help
 

you should make a happy face. you know, happy when stoich and sad when lean.

Re:diy af meter help
 

i have a schematic for one that uses a $12 digital LED panel meter and gives a numerical readout if anyone's interested.

Re:diy af meter help
 

id like to see that

Re:diy af meter help
 

Scarecrow
would you mind shootin that schematic of yours over to me?

thanks

Re:diy af meter help
 

i lied. the panel meters are $15 now, not 12.
they're available at www.web-tronics.com or www.allelectronics.com.

here's the schematic. standard disclaimer applies, don't steal my ---- and sell it. it's for personal/nonprofit use only.

BOM (with web-tronics part #'s):
R1 100k multiturn trim pot, WIW1012-100K $0.89
R2 10K 1/4watt resistor, RA10K, $0.07
C1 0.1uf capacitor, 23BK410, $0.19
C2 1.0uf capacitor, TAC005, $0.87
U1 LM7805 voltage regulator, 7805, $0.86
M1 CX102B panel meter, CX102B, $14.95 (10+, $10.95.. a group buy of the parts may save a couple bucks)
find yourself an enclosure for it and you're good to go.

http://www.imagestation.com/picture/...c/f9f16bf4.jpg
the trim pot can be set with an ohm meter too. there should be 90K between the O2 input and the center pin and 10K between ground and the center pin. fairly simple.


i'm planning on putting some of the schematics i have up on kyle's website. i have stuff like EGT drivers, rev lights, boost controllers, water injection controllers, and i currently have a traction control module almost done.

Re:diy af meter help
 

I don't like loading the O2 sensor like that, the internal resistance is low, I'd prefer using an opamp buffer.

Re:diy af meter help
 

we'll get all that stuff on my site whenever we get around to it, it shouldn't be too hard.

Re:diy af meter help
 

say what? How do you buffer it? And do the comercial gauges do that or do they just read straight off of the sensor like I was going to do?

Re:diy af meter help
 

http://scirocco.dyndns.org/tech/misc...ge/diagram.jpg

that doesn't show where you ground it? I take it that you can ground it wherever as long as it's not between the resistors and the lm3914?

Re:diy af meter help
 

I'm not sure if I understand your question. Just ground everything on the board together, and then run a wire to any good ground on the car. I was going to probably run three wires together to the pos, neg, and signal from the sensor, altho you shouldn't need to do that. You can just ground somewhere closer if you want.