Ventbot fans with 3D printed brackets and control circuit board with ESP32 breakout and multicolored 3D printed cases

Ventbots Are Fans Of HVAC And Home Automation

June 24, 2023 by Michael Shaub 21 Comments

[WJCarpenter] had a common HVAC problem; not all the rooms got to a comfortable temperature when the heater was working to warm up their home. As often happens with HVAC systems, the rooms farthest from the heat source and/or with less insulation needed a boost of heat in the winter and cooling in the summer too. While [WJCarpenter] is a self-reported software person, not a hardware person, you will enjoy going along on the journey to build some very capable vent boosters that require a mix of each.

There’s a great build log on hackaday.io here, but for those who need more of a proper set of instructions, there’s a step-by-step guide that should allow even a beginner hardware hacker to complete the project over on Instructables. There you’ll find everything you need to build ESPHome controlled, 3D printed, PC fan powered vent boosters. While they can be integrated into Home Assistant, we were interested to learn that ESPHome allows these to run stand-alone too, each using its own temperature and pressure sensor.

The many iterations of hardware and software show, resulting in thoughtful touches like a startup sequence that checks for several compatible temperature sensors and a board layout that accommodates different capacitor lead spacings. Along the way, [WJCarpenter] also graphed the noise level of different fans running at multiple speeds and the pressure sensor readings against the temperatures to see if they could be used as more reliable triggers for the fans. (spoiler, they weren’t) There are a bunch of other tips to find along the way, so we highly recommend going through all that [WJCarpenter] has shared if you want to build your own or just want some tips on how to convert a one-off project to something that a wider audience can adapt to their own needs.

See a video after the break that doesn’t show the whole project but includes footage of the start-up sequence that tests each fan’s tachometer and the customizable ramp-up and ramp-down settings. Continue reading “Ventbots Are Fans Of HVAC And Home Automation” →

The Dynamotor Simplified

April 11, 2021 by Al Williams 28 Comments

[Robert Murray-Smith] doesn’t like the price of inverters to convert DC to AC. That led him to build a dynamotor, or what is sometimes called a motor-generator set. These devices are just DC motors driving a generator. Of course, motors can also be used as generators and [Robert] had a stack of brushless motors in the form of PC fans. A two-fan dynamotor was born.

The brushless motors are attractive because, traditionally, the brushes are what usually fail on a dynamotor. The fan that will act as a generator needs some surgery, but it is simple. He scraped off all the control electronics and connected wires to the coils to form a three-phase generator. There’s no need for the fan blades in that configuration, either. If you were using ordinary motors and a generator, getting shafts concentric would be an important task. With the fans, it is simple to just line up the mounting holes and you get perfect alignment for free.

How does it work? [Robert] has a second video showing the output on a scope. You can see both videos below. The dynamotor makes a good-looking sine wave, probably much better than most reasonable-priced solid state inverters. He didn’t mention how much current he could successfully draw, but it probably isn’t much. You’d also need a transformer to replace a commercial inverter that would put out line voltage, so that would be some more loos in the system. On the other hand, if you wanted AC at a lower voltage, you might just replace all the transformers, if you were building a piece of gear yourself.

We’ve looked at how these things work in some detail. There were common in old tube radios, particularly military ones.

Continue reading “The Dynamotor Simplified” →