The site controller board

Homebrew Dam Control System Includes All The Bells And Whistles

Over on brushless.zone, we’ve come across an interesting write-up that details the construction of a dam control system. This is actually the second part, in the first, we learn that some friends purchased an old dysfunctional 80 kW dam with the intention of restoring it. One friend was in charge of the business paperwork, one friend the mechanical side of things, and the other was responsible for the electronics — you can probably guess which ones we’re interested in.

The site controller is built around a Nucleo-H753 featuring the STM32H753ZI microcontroller, which was selected due to it being the largest single-core version of the dev board available. This site controller board features a dozen output light switches, sixteen front-panel button inputs, dual 24 V PSU inputs, multiple non-isolated analog inputs, atmospheric pressure and temperature sensors, multiple analog multiplexers, a pair of SSD1309 OLED screens, and an ESP32 for internet connectivity. There’s also fiber optic TX and RX for talking to the valve controller, a trio of isolated hall-effect current sensors for measuring the generator phase current, through current transformers, four contactor outputs (a contactor is a high-current relay), a line voltage ADC, and the cherry on top — an electronic buzzer.

The valve controller has: 48 V input from either the PSU or battery, motor phase output, motor field drive output, 8 kV rated isolation relay, limit switch input, the other side of the optical fiber TX and RX for talking to the site controller board, and connectors for various purposes.

If you’re interested in seeing this dam control system being tested, checkout the video embedded below.

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Just a simple Lego bouncy DVD logo screensaver mechanism. (Credit: Grant Davis, YouTube)

Building The DVD Logo Screensaver With LEGO

The completed Lego DVD screensaver. (Credit: Grant Davis, YouTube)
The completed Lego DVD screensaver. (Credit: Grant Davis, YouTube)

There’s something extremely calming and pleasing about watching a screensaver that merely bounces some kind of image around, with the DVD logo screensaver of a DVD player being a good example. The logical conclusion is thus that it would be great to replicate this screensaver in Lego, because it’d be fun and easy. That’s where [Grant Davis]’s life got flipped upside-down, as this turned out to be anything but an easy task in his chosen medium.

Things got off on a rocky start with figuring out how to make the logo bounce against the side of the ‘screen’, instead of having it merely approach before backing off. The right approach here seemed to be Lego treads as used on e.g. excavators, which give the motion that nice pause before ‘bouncing’ back in the other direction.

With that seemingly solved, most of the effort went into assembling a functional yet sturdy frame, all driven by a single Lego Technic electromotor. Along the way there were many cases of rapid self-disassembly, ultimately leading to a complete redesign using worm gears, thus requiring running the gears both ways with help from a gearbox.

Since the screensaver is supposed to run unattended, many end-stop and toggle mechanisms were tried and discarded before settling on the design that would be used for the full-sized build. Naturally, scaling up always goes smoothly, so everything got redesigned and beefed up once again, with more motors added and multiple gearbox design changes attempted after some unfortunate shredded gears.

Ultimately [Grant] got what he set out to do: the DVD logo bouncing around on a Lego ‘TV’ in a very realistic fashion, set to the noise of Lego Technic gears and motors whirring away in the background.

Thanks to [Carl Foxmarten] for the tip.

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