DIY Air Fuel Ratio Meter Gauge

Yesterday, I just browsing through internet to find some information regarding AFR meter. Than i stumble upon a video on youtube on DIY AFR. just require some small amount of money, soldering skills and some free time to complete the job. Than i think its maybe suited me.

Than I gather some more information on the net on how to make this things. I am on this two website.

The 1st one is D.I.Y. air/fuel ratio meter on Redline

It got all the information i need to DIY this thing. However, bacause it's lack of information. i decide to dump the idea. from the website.

Than I am into this website DIY Air / Fuel Ratio Metering by Wing Gee. It's got a lot of information and i decided to go with the idea from the website. here's the circuit for the gauge.



Than I went to a electronics shop and buy all the components related to the gauge. i got all of it just for RM13. Pretty cheap if compare with a proper AFR gauge that require at least RM80

Than using my skills, i assemble all the components altogether. Here's the details on led color stands for.

0.0V-0.2V stands for lean mixture as red led
0.3V-0.8V stands for stoich mixture as green led
0.8V-1.0V stands for rich mixture as yellow led

LM3914 and 5V voltage regulator circuit board
(Front)


LM3914 and 5V voltage regulator circuit board
(Back)


10 LED connected


Full size meter gauge


Installed in the car


Here's the meter on action