Simple Fan Speed Controller

As mentioned at the end of the Ming Pi video, one of my challenges with setting up a home temperature monitoring system was the noise of the fan in the power supply. The other being the battery life, that will be covered in a different project.

There was a small space in the PSU behind the fan which I thought would be just big enough to add a fan controller. I checked the voltage going to the fan and it was about 10v.

So I’ve designed a circuit that uses a DS18B20 temperature sensor and a microcontroller to generate a PWM signal to drive the fan. A TIP31C transistor is used apply the power to the fan.

My first step was to prototype a circuit using an Arduino UNO. That allowed me to use the serial debugging to read the temperature from the sensor. I then added an LED to test the PWM signal and finally swapped that out with the power transistor.

Once I was happy that worked, I swapped in a much smaller board I had available. The Digispark Pro which is based on the ATTiny167 MCU. There was a slight challenge there with the temperature library in that it expected a yield function to be defined. So I declared a simple empty version of that which worked ok. It might be that including the Scheduler library would have also worked?

I tested the new circuit with the real fan and ran it from my bench power supply as that allows me to limit current and hence protects the components if I get the assembly incorrect.

My last step is to solder the components onto a strip board and from there I’ll mount it into the case, likely with a stick foam pad, taking care to insulate it from the case and other components. I’ll add some photos once I’ve done that.

The circuit ended up fairly simple, as did the Fan Controller code.

Inspired by Flash Gordon

Inspired by Flash Gordon

My recent project on Element14 was to capture temperature from around the house and post it to a central dashboard. I used a set of software including Mosquitto, InfluxDB, Node Red and Grafana or Ming for short. The dashboard is

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DIY: How To Make A Rope Harness For Tree Climbing

DIY: How To Make A Rope Harness For Tree Climbing

A rope harness is a type of safety equipment you can wear when climbing trees. This harness will help you stay safe in case something goes wrong, such as a branch breaking or someone falling out of the tree. There

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MakerSpace Magazine

MakerSpace Magazine

On a recent trip to the states, I dropped into Barnes and Noble to see if there were any interest magazines. And I was not disappointed. As well as finding a copy of Machinist’s Workshop with a differential chain hoist,

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How to Introduce Your Kids to Woodworking [5 Easy Steps]

A woodworking bench with tools such as saws and files

Want to teach your kids the art of woodworking? This can be a hard task. Here, you’ll find five steps to introducing woodworking to your kids.

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Pi and Chips

Pi and Chips

I’ve been working on another electronics video, as part of that I need a large Raspberry Pi logo. I looked online and there were some stickers but most of them were smaller than I wanted. So I decided to 3D

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Potion Rack

Potion Rack

The latest video is up on Element14 Presents, “Using 555 Timers to Make a Magic Potions Rack“. The video is about the electronics behind the potions so I thought I’d also give a mention to the woodwork behind the project.

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Rustic Sawhorse

Rustic Sawhorse

I’ve been slowly working through a big pile of logs sawing and splitting the wood. The smaller bits will be used on our firepit and the larger, I hope to get some planks and spars to make projects with. I’d

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