An interface to the MKS 901P transducer

Every fusor and fusion system seems to need a vacuum. This area is for detailed discussion of vacuum systems, materials, gauging, etc. related to fusor or fusion research.
ian_krase
Posts: 425
Joined: Mon Nov 28, 2016 7:48 am
Real name: Ian Krase

Re: An interface to the MKS 901P transducer

Post by ian_krase » Fri Nov 17, 2017 7:07 am

PM sent. I'm interested.

Bruce Meagher
Posts: 103
Joined: Fri May 13, 2011 3:25 am
Real name: Bruce Meagher
Location: San Diego

Re: An interface to the MKS 901P transducer

Post by Bruce Meagher » Wed Dec 20, 2017 12:56 am

Finn graciously sent me a couple of his boards to try. After a few mishaps I was able to get to them working. Here are my notes for others that might try building these. First, the cheap monochrome oled display I purchased from eBay had the VCC and GND pins swapped (even though the first image in their listing showed otherwise!). Second, I used a 180k resistor on the boost converter PS board to get ~11.5V, but unfortunately my cheap eBay arduino pro mini’s voltage regulator couldn’t handle that. Third, the lipo battery had to be connected to power on the 901p. I haven’t debugged why the little boost converter couldn’t supply enough current when the battery was not connected. The 901p only requires ~35mA when running at 11V.

Future enhancements could possibly include moving the power switch away from the power cable to make it easier to turn on, supplying the Arduino with 5V instead or 11V to lower power consumption, add usb, ethernet, or wifi support to allow for easy remote monitoring. Another project to add to my list.

Thanks for sharing Finn!

P.S. My fat fingers hate working with surface mounted parts!
IMG_9112.JPG
Finn's vacuum controller connected to the MKS 901p

User avatar
Finn Hammer
Posts: 84
Joined: Sat Mar 05, 2016 12:21 pm
Real name: Finn Hammer
Contact:

Re: An interface to the MKS 901P transducer

Post by Finn Hammer » Wed Dec 20, 2017 6:06 pm

Bruce,

I am glad you got the boards working, that pin reversal on the LED display was a nasty one.
Regarding your choice of buss voltage, I had a similar issue, and also fried a Micro, or it's voltage regulator. That is why I recommended setting the common supply voltage to 9V, which is the minimum voltage required by the 901P, and also the maximum allowed for the Micro.
The combined battery charger/boost converter is another cause of head scratching, because it would appear that it actually discharges the battery, ever so slightly. So the power switch should be on the battery line to the charger/boost module, something I avoided because I find it un-beautifull to have to turn the unit on, in order to charge the battery.
The whole idea with this little project was to present something that could be made without too much soldering, and using readily available parts. If I should do it again, I would mount all parts relating to battery charging, supply voltage generation and signal conversion right on the board, but then It would be a much more involving project.

Cheers, Finn Hammer

Bruce Meagher
Posts: 103
Joined: Fri May 13, 2011 3:25 am
Real name: Bruce Meagher
Location: San Diego

Re: An interface to the MKS 901P transducer

Post by Bruce Meagher » Wed Dec 20, 2017 9:11 pm

It’s definitely an excellent little board, and I appreciated you sharing. The battery probably isn’t an ideal fit here. With the battery at 3.7V I’m drawing about 290mA when running. That’s only a few hours between charging. I’m also draining about 450uA when off.

I find these diversions, while traveling on the path to fusion, what I enjoy most. I’ve ordered a couple ESP32s to continue that journey. I’ll share if/when I get it working.

Bruce

User avatar
Richard Hull
Site Admin
Posts: 10737
Joined: Fri Jun 15, 2001 1:44 pm
Real name: Richard Hull

Re: An interface to the MKS 901P transducer

Post by Richard Hull » Thu Dec 21, 2017 11:22 pm

The road to fusion involves many technologies and sciences. There is a joy in the hands-on effort, and we all enjoy the many teachable moments that will be encountered on the way to the ultimate goal. There are many small and large increments in the process that demand our attention. We are are all made better for it , in the end.

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
Retired now...Doing only what I want and not what I should...every day is a saturday.

Post Reply