Hi Kiss,
Yes, I was actually thinking about making up a laminar flow element which I will do now.
After looking closely at this after fixing the noise issues, it is not noise or interference now but rather a variation from Turbulent flow past the tap point for the sensor tube.
The variation is 30mV, I changed the resolution of the sensor circuit to 4V = 25" of water & this has helped a little but the PID is trying to correct for the fast fluctuations of the 30mV.
This circuit is only for holding a precise pressure as my other recordable readings are from actual Turbulent flow for a very good reason unlike many Flow Test Benches.
Yes, like you & Tony have mentioned I could try to get the PID to ignore that amount of variation but unfortunately this is around 0.2" or 5mm of water, it doesn't sound like much but when recordable flow readings are taken from inclined manometers chasing fractional HP this is quite a lot.
I know that may sound like BS!
The reason for the accuracy is that since I have not been able to work any more, my grandson has conned me into building his very small Gokart engines for racing.
This has prompted me to make this controller as I can not get the fine adjustments required manually anymore as stated before due to health reasons.
You may not be interested but seeing your Snowed in you may have time to look at this video of my grandson with an engine I built for him before being layed up.
He is only 12 but doing very well, you will see in the video that it takes him a lap or two to warm things up then he gets into it.
Have a look, the little bugger can drive & wrings the engines neck, not because he is my grandson either, if you look at the front wheels he is actually driving this thing with a bent steering arm in this video & it's way out of control.
I added the ___ so it didn't put the video here.
**broken link removed**
This is why fractional HP is required now & precision for the Flow Test Bench & why I am so interested in trying to work this out as it gives me the opportunity to do what I love doing (building engines) once again although on a very small scale this time.
I'll make some changes & see how I go.
Oh yeah, you will see my sons big ugly head in the video as well
.
Cheers