Planning a DIY Data Acquisition/Engine Controller

[AdeV]

I found the thread (eventually) here: http://www.microcogen.info/index.php?topic=927.msg11364#msg11364

As most commentators noted, the results are basically junk for various reasons; however, I still find them interesting. I've yet to make the thermocouple holder, maybe this renewed interest will spur me on.

Basically, the highest temperature I saw was 310^oC; however, it was probably somewhat hotter by the manifold. I'll repeat the experiment once I've re-done my cooling system, and various other tasks

[carbon-rod]

I just had a read of your post!! man it made me laugh "Due to a combination of wood smoke and diesel fumes, the test was then terminated and the engine shut down." haha I  can just imagine, you can only apply so much load before you start a wood fire! you maybe need some Jarrah for longer term loading? hehe

hmm, so did you ever end up making the thermowell for the thermocouple? I'm sure you lost a few degrees in the piping before hand but I doubt it has affected the temperature reading that much, I mean the temperature doesn't need to be absolutely perfect, not for these engines any way.

well it will be a few months before I have built my controller and engine / frame / generator, it's a big project and in amongst it I will also be building a new shed as well.... but I am definitely keen to help develop controller for the engine! I want to get the engine to a completely automated stage with starter and speed control with filters and everything, I mean its completely opposite to how the lister was designed but It's not like it's out in a field in a non maintenance condition.

[carbon-rod]

"The AD596/AD597 can operate from a single supply from 5 V
to 36 V or from split supplies totalling 36 V or less as shown.
Since the output can only swing to within 2 V of the positive
supply, the usable measurement temperature range will be restricted when positive supplies less than 15 V for the AD597
and 10 V for the AD596 are used. If the AD596/AD597 is to be
used to indicate negative Celsius temperatures, then a negative
supply is required."

Looking at the chart, using a J type we can read 500 degrees Celcius with our microcontroller which is 5v output, however we need to supply the sucker with 7V to be able to obtain that 5v output, a small linear regulator should do the trick considering current consumption is tiny, an 8 volt reg from farnell is like 30 cents I will have a 12v battery supply and then probably a 7805 5v regulator for power to the microcontroller. There won't be much current draw so I don't see much point in designing a proper power supply circuit, you could use a 5v usb charger from a car but make sure the output is clean because it is a switching supply which can generate noise, I like these though because they are relatively cheap and can efficiently supply 1-1.5 amps producing minimal heat unlike a crappy linear regulator.