Issue link: https://iconnect007.uberflip.com/i/1419905
30 PCB007 MAGAZINE I OCTOBER 2021 Happy Holden: Yes, I was really surprised that on our alkaline etching machines, the control sys- tem was from ADA Tech. When we delved into it and started making measurements closely, we found out that this thing was really imprecise, which got us to brainstorming about how could we build a better specific gravity controller. We actually came up with a $55 one we built our- selves that has +/- 0.001 SG units control. Stepinski: ere you go. Exactly right. Holden: ey have them in the chemical indus- try, but they're $5,000 to $10,000 each, while the one we devised was $55. e mechani- cal engineers kept saying it wouldn't work. We finally dug out the textbooks and showed them, "You don't remember Archimedes' principle, the center of displaced mass. If we submerge the specific gravity sensor, then the mass never changes." ey were saying, "e way you guys got it arranged this thing won't work." But they had just forgotten that little minor part of Archimedes' principle. Stepinski: Yes. Nowadays, they'll do a stand- pipe with a pressure transducer on the bottom, and that's becoming more popular in the mar- ket on newer machines. Holden: We had one of those also. A lot of times, we were taking things out of other segments: automotive, chemical, any place we could find a sensor that could be adapted to printed circuits. And, of course, digitization of the automobile was great because then we got low-cost volume sensors that they used to measure gasoline flow. Rather than spend- ing a lot of money on very precise metering pumps, we just bought precise flow-measuring devices, and not precise metering pumps. Stepinski: Yes. I agree. I've gone to trade shows outside of our industry to learn a lot myself, because just staying in our industry trade shows restricts your vision a bit. Going out- side and bringing in equipment from other industries was a big component of what I did at GreenSource. Matties: ank you so much, Alex. Stepinski: It was nice speaking with you too. PCB007