Cheap AFR meter

Malachy · Post by **Malachy** » Tue Jul 04, 2006 7:22 am

Cheap Afr Guage?
hi i have been toying with this idea with mad professor from here.
i have an LC-1 and want an afr guage, however my options are:
i can either spend a silly amount on an xd1 or spend alot less on some cheap budget guage that looks rubbish.
so we were chattingand came up with the idea of setting one of the LC-1 outputs to read
1v @10:1 afr
and
2v @ 20:1 afr
then wire in a Voltmeter that reads 1-2v
this would mean at 1.500V the Afr would be 15:1
etc
using something like this
http://cgi.ebay.co.uk/DC-0-2V-50V-3-BLU ... dZViewItem
from ebay.
it should give me an accurate afr reading costs next to nothing and will look quite tidy sunk flush into the dashboard.

Any problems people can see?
feedback apreciated

edit: reading it again its not very clear however it seems you may be able to move the decimal place so 1.500v shows on screen as 15.00 which wouldbe a bonus!

jsmcortina · Post by **jsmcortina** » Tue Jul 04, 2006 8:14 am

Sounds like a plan.

James

jakobsladderz · Post by **jakobsladderz** » Tue Jul 04, 2006 4:36 pm

you can get panel meters cheap that display 0-200 mv (so you'd use a resistor divider to drop your 1-2 volts to .1-.2 volts). you set a jumper to define the position of the decimal point so you could have it display 10.0-20.0.. They're about $9-$10 each or something.. Just be sure to get one that will measure relative to power ground, some of them have a common mode input that can't get within a volt or two of ground and would not work without a bipolar supply.

jakobsladderz · Post by **jakobsladderz** » Tue Jul 04, 2006 4:40 pm

Sorry, should've followed the link first... Looks like these may have the decimal point move feature supported using the dip switch somehow.. don't know about the input relative to ground thing for these particular displays but given the internal volt reg I'd say it will probably be OK..

Malachy · Post by **Malachy** » Tue Jul 04, 2006 11:44 pm

i recieved my lc1 today and i should begetting the panal meter in thenext 2-3 days so will keep this updated.

bluetrepidation · Post by **bluetrepidation** » Wed Jul 05, 2006 2:34 pm

Good idea. Though it may not be too accurate being that it sweeps only over 1 volt but for something you are reading manually how accurate do you need it? I bet it'll work great.

A.J.

fscott · Post by **fscott** » Thu Jul 06, 2006 8:24 am

That meter will work perfectly.

The nice thing about hte LC-1 is that you can calibrate the outputs. So even if the meter isn't accurate, you can make it accurate by adjusting the LC-1's output.

See this thread.
http://www.msefi.com/viewtopic.php?t=17314&highlight=

Fred

Malachy · Post by **Malachy** » Tue Jul 11, 2006 6:21 am

ok so i got the meter today and managed toget it displaying 15.40 @1.540 volts (aa battery)

thats as far as my testing has got as my ms seems to still be stuck in uk customs :/

although for accuracy the voltmeter is adjustable and can be calibrated via a Pot on the back

i checked it versus my Dmm (which is a cheap one)
dmm= 1.544 volts
voltmeter = 1.540 volts

so not a huge difference

TPI 85 Blazer · Post by **TPI 85 Blazer** » Wed Jul 26, 2006 4:55 pm

I had thought of the same idea. It's easy with an LC-1. You just get any meter and figure out the relationship between input voltage and it's display. Then you reverse this and program it into the extra analog out on the LC-1.

Fastest95PGT · Post by **Fastest95PGT** » Thu Jul 27, 2006 4:00 am

This is absolutely a great idea. I had thought of it earlier on when I got tired of using my NB Autometer gauge (already had it) and guessing the lights and their conversion to AFR at a glance.

I bought a XD-1 though because I can't multiply by 10 fast enough!