digital steam engine indicator

A special section just for steam engines and boilers, as without these you may as well fit a sail.
Steam Captain
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Re: digital steam engine indicator

Post by Steam Captain » Thu Feb 20, 2020 9:31 pm

So,

The separate calculation of the medium pressure is done.
The calculation of the power is done.
Everything is prepared so far for the addition of the display.

Now, my todo list has changed a little:

The metric/imperial options will definitely be implemented. It's too easy not to do. It is just using different constants.
I definitely decided for a TDC sensor subroutine, as it will make turning the crankshaft into position obsolete AND will add the important possibility of a self-correcting algorithm.

The input options so far contain the 4 variables: stroke, bore, con rod length and single or double acting. These will be the only variables asked for by the program.

My step now is to bring it to the physical world and attach it to a fridge compressor, because I need readings with real pressure values under real life conditions. Until now, I helped myself out with virtual pressure readings. I do suspect, that the 1-2ms response delay of the pressure sensors I've found will be very limiting for the rpm.
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Re: digital steam engine indicator

Post by Steam Captain » Thu Mar 19, 2020 8:38 am

Soo, many things happened.

I have figured out how to draw stuff on an Arduino screen and this is the first try I got:

Image

It isn't visible on the photo, but the green is like REAL green. Bright as can be. Right out of a neon pencil.
I am going to change the display color to a warm one like orange or maybe I am going to use a black background with everything drawn in warm colors like orange or red, since it is more pleasant for the eyes. The display is a 2.4" tft screen. Maybe I opt for an a little bigger screen like 3.5", but this is already ok for testing. The only worries I have is, that the 2.4" screen does get a little small if I want to display all the numbers AND the pV-diagram. And I want.

So, let's just see. I am currently working on passing a financial bottleneck and get my tools into this city and then, I can continue with the project. I did for example find out, that there are encoders with z-channels (one impule per rotation). This means I wouldn't need any additional hall sensor shenanigans.
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Re: digital steam engine indicator

Post by TahoeSteam » Fri Mar 20, 2020 3:42 am

You're making some real progress! I'm excited to see your final product and how it works. Nice work!

Please stay safe.
~Wesley Harcourt~
Check out the steamboat and steamSHIP videos on my YouTube page: https://www.youtube.com/c/wesleyharcourtsteamandmore
Steam Captain
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Re: digital steam engine indicator

Post by Steam Captain » Wed May 20, 2020 4:01 pm

As a major challenge in life has made me lose almost al my belongings a couple of months ago, including my workshop, I have to start anew.
I now have a garage I am equipping with new tools and everything to continue with my hobby. The good thing is, that I now can have a real workshop with ground-level accessibility (It WAS tricky having a workshop in a 8m² tenement building cellar.

Since the steam virus knows no cure, I'm still planning on building the opposed-piston steam engine project, the digital steam indicator and a gasoline-fueled monotube boiler.

This project hasn't been affected so much, because all the stuff I did here was after the loss.
As an update, a fridge compressor is lying in my garage workshop waiting for a simple slide valve arrangement to be screwed on its cylinder head. Since I have to completely equip a new workshop, I didn't want to wait so long to build the steam engine to test the indicator. Technically, I just need some mechanical contraption with an axis to strap the decoder on and a displacement space with a fluctuating pressure to test the indicator.

Until now, I've used a decoder without a z-channel. This is a channel, that gives off one pulse per rotation. This means I wouldn't even need an external rpm counter and just use the z-channel. There is the amazing advantage that one can use this signal to eliminate erroneous ping countings adding up over many rotations, simply by starting the program loop whenever the z-channel pings. It really makes things MASSIVELY easier.
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