A Guide to Cheap DIY Datalogging

If it isnt a problem or a suggestion it probably goes here.

Moderator: Matt

Mike_GruiZinga
 

Posts: 8
Joined: Thu Sep 10, 2009 10:28 pm
Location: Kalamazoo, Michigan

A Guide to Cheap DIY Datalogging

Post by Mike_GruiZinga »

Street Tuning my Z31 using Nistune and the stock sensors wasnt providing the capability I wanted. I did some research online, and here is what I found. Much of this is already covered through various resources, but here it is all in one place.

DLP Designs A/D Converter $30
http://www.dlpdesign.com/usb/io8.shtml
Image
DLP designs has created a 8 channel USB powered data acquisition card. It allows for eight 0-5 volt inputs, and provides a 5 volt output for powering your sensors. It is fast, and appears to be the cheapest DAQ option on the market right now. It interfaces with Nistune, allowing logging and monitoring of up to 8 channels.

Sensors
Temperature (intake) ($5)
http://search.digikey.com/scripts/DkSea ... 8B20%2B-ND
Image
This thermometer is made by Dallas Semiconductor. It requires Ground, 5v input, and outputs a linear 0-5v signal. It has a sensing range of -55ºC to 125ºC; perfect for monitoring inlet air temperatures. It is fast, and accurate within a couple of degrees. The are $5 on digikey.com

MAP Sensor ($10 or Free)
http://www.freescale.com/webapp/sps/sit ... de=MPX4250
Image
All of the MAP sensors on the market are $50 and above. Alternatively you may be able to find a GM 3bar sensor in a junkyard. OR you could purchase the motorola MPX4250. This is a 2.5bar MAP sensor designed for automotive applications. It is fast, and accurate within .5psi. It requires ground, 5 volts input, and it outputs a linear 0-5v signal. If you ask freescale.com nicely, they will send you free samples. Otherwise they can be ordered from digikey.com. If your clever, you can also buy the harness for these sensors. I just wired it myself, whatever.

Exhaust Gas Temp ($35 plus probe)
http://www.o2simulator.com/index.php?ma ... ucts_id=13
Image
Logging EGT requires a K-type thermocouple and an amplifier. Unfortunately, most the amplifiers on the market, both lab use and automotive use are $150 to $300 and multichannel. AEM sells a nice unit, if thats what your looking for. If you only want a single channel, buy the above converter, and any high temp K-type thermocouple (ebay, whatever). A thermocouple outputs a mV, non-linear signal. The amplifier/converter changes the signal to linear 0-5V output. Alternatively, you can make your own amplifier converter using this little surface mount chip from digikey and a few resistors ($10 or less cost). There are guides all over the internet on how to do this. IMO, just buy the pre-made circuit.

Wideband Logging
Most Widebands have a semi-linear 0-5 volt output. Nistune supports many of these. IF nistune does not support your wideband, you can use the DLPDesigns board to log your wideband. This is the easiest way to log an AEM UEGO gauge.

Detonation Monitoring ($10)
Okay, this method doesnt actually log detonation through a channel of the DLP designs board. Using the 5v signal and ground from the DLP designs board, you can power a 3-wire condenser microphone. Simply JB weld the condenser microphone to your factory detonation sensor, and supply the output signal to a headphone jack. Use your computer and a sound recording program to listen to the microphone. This works amazingly well, and is better explained on many other automotive forums.
If you dont want to use your laptop (or it doesnt have a line-in) you can use a cheap tape recorder, or build your own amplifier circuit: http://home.netcom.com/~bsundahl/knock/ ... listen.htm

Wiring
So you have several sensors which all require 5 volts and ground. The sensor can share ground and 5volt signals, which can be provided from the DLPdesigns converter. Each sensor will require its own output signal wire. The easiest way to "build" a sensor harness is to simply use a CAT 5 ethernet cable. An ethernet cable has 8 wires bundled inside it. It works well, and it allows your entire system to be mobile. Since everything is on one harness, you can transfer it all to whichever car your working on.
PL
 

Posts: 957
Joined: Fri Feb 03, 2006 3:29 pm
Location: Adelaide, South Oz
Contact:

Post by PL »

Awesome work Mike!! Well done indeed.

I know how much work is involved in gathering info like this together.

I usually leave the boost measurements to the dyno that I use but I've had cause to question its accuracy lately, so I think I'll hook up the DLP and a boost sensor so I can log boost directly into NIStune.

I'm sure I got a sample pressure sensor from Freescale at one stage. I reckon Matt's still got my DLP though. Matt?

PL
chris2712au
 

Posts: 343
Joined: Thu Jun 19, 2008 1:52 am
Location: sydney australia

Post by chris2712au »

I use a 3bar gm delco.. and have the lookup tables.. works a treat..
PL
 

Posts: 957
Joined: Fri Feb 03, 2006 3:29 pm
Location: Adelaide, South Oz
Contact:

Post by PL »

I just found my Freescale MPX4250GP. :)

Now if I can just find my DLP converter I'll be in business!

PL
PL
 

Posts: 957
Joined: Fri Feb 03, 2006 3:29 pm
Location: Adelaide, South Oz
Contact:

Post by PL »

Looks like I'm all set - Matt's got my DLP. :)

PL
PL
 

Posts: 957
Joined: Fri Feb 03, 2006 3:29 pm
Location: Adelaide, South Oz
Contact:

Post by PL »

For those in The Land of Oz - I just found out that you can actually get the Freescale pressure sensors from Farnell for $AU20. Plus overnight delivery.

http://au.farnell.com/freescale-semicon ... dp/1555610

Or you can just get a sample from the Freescale website...

Either way is a good option. When these were a Motorola part they were quite hard to get. Now that they're Freescale it's very easy. :)

PL
chris2712au
 

Posts: 343
Joined: Thu Jun 19, 2008 1:52 am
Location: sydney australia

Post by chris2712au »

wish I would have known that my gm delco 3bar cost me 60 bucks.. how many bar is the free scale ?
chris2712au
 

Posts: 343
Joined: Thu Jun 19, 2008 1:52 am
Location: sydney australia

Post by chris2712au »

anyone have the look up tables for an RTD ??
JM
 

Posts: 21
Joined: Fri Nov 27, 2009 6:43 am

Re: A Guide to Cheap DIY Datalogging

Post by JM »

i like it much, but i have two questions:
How to tighten wires from air intake sensor to not have leaking piping?
And can i use the EGT amplifier a split wires from my greddy egt to have it logging?
thanks
chris2712au
 

Posts: 343
Joined: Thu Jun 19, 2008 1:52 am
Location: sydney australia

Re: A Guide to Cheap DIY Datalogging

Post by chris2712au »

If it is under pressure normally I weld on a nipple to the pipe stick the sensor in and slide some tube / vac line over the top and clamp both ends.. one clamp on sensor and other clamp on nipple..

if it is not then you can clamp on the cables cause it is under vacuum and wont leak as easy.. so it does not have to be done up as tight..

The dlp will take any 0-5 volt signal and then just set up the look up tables..
Dark Diver
 

Posts: 12
Joined: Thu Sep 25, 2008 8:28 pm

Re: A Guide to Cheap DIY Datalogging

Post by Dark Diver »

And can i use the EGT amplifier a split wires from my greddy egt to have it logging?
JM, an EGT probe uses special wires that are made from Chromel for the one and Alumel for the other. You need to use only those alloys till the amplifiers which include a temperature compensation.
klys
 

Posts: 21
Joined: Tue Jun 09, 2009 1:28 pm
Location: Montreal, Qc, Canada

Re: A Guide to Cheap DIY Datalogging

Post by klys »

wow that is great info
thanks for the nice write up too!
sssbassil
 

Posts: 49
Joined: Sat Sep 04, 2010 8:42 pm
Location: new zealand

Re: A Guide to Cheap DIY Datalogging

Post by sssbassil »

DLP Designs A/D Converter

can u buy this in oz somewhere?

$57 shipping to nz a bit much, will if i have to tho
Matt
Site Admin
 

Posts: 8961
Joined: Sun Jan 29, 2006 1:45 am
Location: Adelaide, Australia
Contact:

Re: A Guide to Cheap DIY Datalogging

Post by Matt »

I have two spares... cost price plus $15AUD postage
sssbassil
 

Posts: 49
Joined: Sat Sep 04, 2010 8:42 pm
Location: new zealand

Re: A Guide to Cheap DIY Datalogging

Post by sssbassil »

sweet, keen az
Post Reply