Cheap AFR meter

TPI 85 Blazer · Post by **TPI 85 Blazer** » Fri Jul 28, 2006 3:25 am

Fastest95PGT,
I was thinking of getting a NB gauge and connecting it to a power supply to measure with a multimeter the voltage at which each light turns on. Then put those numbers into Excel and invert the function. Program the LC-1 as close to that as possible and the NB gauge should work as a WB gauge. I think the LC-1 is intended to do this.

Fastest95PGT · Post by **Fastest95PGT** » Fri Jul 28, 2006 3:47 am

TPI 85 Blazer wrote:Fastest95PGT,
I was thinking of getting a NB gauge and connecting it to a power supply to measure with a multimeter the voltage at which each light turns on. Then put those numbers into Excel and invert the function. Program the LC-1 as close to that as possible and the NB gauge should work as a WB gauge. I think the LC-1 is intended to do this.

The problem with using a NB gauge though for those of us who are boosted and run pretty tight tolerances is that we can't just use the green LEDs as being rich. I need to know when I'm at 11 AFR as 12 AFR will quite possibly do some damage (boosted 10:1 cast internals).

I definitely like this volt meter gauge especially with the 1-2V 10-20AFR range as it's accurate * 10 which is very simple to read (I was kidding about not being able to multiple by 10 fast enough).

TPI 85 Blazer · Post by **TPI 85 Blazer** » Sat Aug 19, 2006 4:46 am

I picked up one of these from Summit racing. They are only $33.50, so generally backordered. I checked it out with a voltmeter and power supply and it is basically linear from 0-1V, except that below 0.2V, it stops moving (the bottom 10% of the scale is never used). So I programmed that curve into the extra analog out of the LC-1 and the reading in MT match pretty well. There are basically 10 tick marks, which correspond to 20:1 - 10:1.

It has nice EL backlighting which makes my other A-pillar gauges look bad, but sadly, the dimming feature seems backwards. As my other lights get brighter, this gauge gets dimmer. I might make a 1 transistor inverting circuit to fix this.

I know this isn't super low-buck, but I like the looks of an actual "gauge" instead of a "voltmeter".

T3Bunny · Post by **T3Bunny** » Thu Aug 24, 2006 9:07 am

Guys, if you read through the documentation supplied with the LC-1 and LM-1 units, Innovate describes using the panel meters.

A BIG advantage of the panel meter is that you can get them to read a direct AFR. When you set it up right, it will read 14.7 at an afr of the same. You can get nice meters backlighted and all for under $70 from DigiKey. And I have seen them for as low as $10-20 for ones with less frills.