Tube Tumbler Provides The Perfect Culture

We’ve all had to shake jars of nail polish, model paint, or cell cultures. Mixing paint is easy – but bacteria and cells need to be agitated for hours.  Happily, laboratory tube tumblers automate this for us. The swishing action is handled with rotation. The vials are mounted at angles around a wheel. The angular offset means the tubes are inclined as they rise, and declined as they fall. This causes the liquid in the tube to slosh from one side to the other as the wheel rotates.  [Sebastian S. Cocioba] aka [ATinyGreenCell] released his plans through Tinkercad and GitHub, and with a name like Sir Tumbalot, we know he must be cultured indeed.

Grab your monocles. Version 2 features a driven wheel lined with magnets to attach tube adapters, and he’s modeled 50mL and twin 15mL tube holders. The attachment points look like a simple beveled rectangle with a magnet pocket, so if you’re feeling vigorous for vials, you can whip up custom sockets and tumble any darn thing. A Trinamic StealthChop chip on a custom PCB controls the pancake stepper, and the whole shebang should cost less than $50USD. We’re wondering what other purposes this modular design could have, like the smallest rock tumbler or resin print rinser.

Making lab equipment is phenomenal for saving money for things that just spin up to a biotech lab.

Continue reading “Tube Tumbler Provides The Perfect Culture”

Save Money And Have Fun Using IEEE-488

A few months ago, I was discussing the control of GPIB equipment with a colleague. Based on only on my gut feeling and the briefest of research, I told him that the pricey and proprietary GPIB controller solutions could easily be replaced by open-source tools and Linux. In the many weeks that followed, I almost abandoned my stance several times out of frustration. With some perseverance, breaking the problems into bite-sized chunks, and lots of online searching to learn from other people’s experiences, my plan eventually succeeded. I haven’t abandoned my original stance entirely, I’ve taken a few steps back and added some qualifiers.

What is GPIB?

Example of HP-IB block diagram from the 1970s, from

Back in the 1960s, if test equipment was interconnected at all, there weren’t any agreed-upon methods for doing so. By the late 60s, the situation was made somewhat better by card-cage controller systems. These held a number of interface cards, one per instrument, presenting a common interface on the backplane. Although this approach was workable, the HP engineers realized they could significantly improve the concept to include these “bridging circuit boards” within the instruments and replacing the card cage backplane with passive cables. Thus began the development of what became the Hewlett-Packard Interface Bus (HP-IB). The October 1972 issue of the HP Journal introduced HP-IB with two main articles: A Practical Interface System for Electronic Instruments and A Common Digital Interface for Programmable Instruments: The Evolution of a System. Continue reading “Save Money And Have Fun Using IEEE-488”