Quieting an inexpensive bench power supply

[Mike] just purchased this Atten APS3005S bench power supply for around $80. It does the job, but boy is it noisy! We were pretty surprised to hear it fire up in the video after the break. To make matters worse, the noise is persistent since the fan never shuts off. Having worked with other bench supplies he knew that a common feature included in many models is temperature controlled case fans. He set out to quiet the fan and implement a temperature switch.

For this project [Mike] had the benefit of looking at a nearly identical model that does have temperature switching. He discovered that the board on this one has a through-hole zero ohm resistor populated in place of a thermostat switch. That switch closes the connection at or above 45 degree Celsius, thereby turning on the cooling fan. Bridging the traces with a zero ohm resistor to save on production costs is what caused the fan to run continuously. After replacing the resistor with a KSD-01F and swapping out the stock fan for a high-quality version [Mike] has takes a noise maker and turned it into a device that’s kind to the ears.

[Read more...]

DIY thermostat keeps the harsh winter cold at bay

diy_attiny_thermostat

[Phil’s] parents grow their own organic food, but the harsh Ukraine winters make storing it a difficult proposition. Since it can drop to -30°C on occasion, they asked him to find a way to keep their storeroom at around 5-7°C above zero. He decided to construct his own programmable thermostat to keep things in check, and has been documenting the process as he goes along.

The thermostat uses a DS18B20 temperature sensor to monitor the room, and the logic is handled by an ATtiny2313. When the temperature dips low enough, the ATtiny triggers the room’s heater via a standard 240v relay. He can check the current temperature via a small 7-segment display mounted on the control board, which also contains three microswitches for controlling the heater.

It looks like a pretty solid build so far, and while he hasn’t finished coding the thermostat just yet, [Phil] says that those details are forthcoming. He has published a schematic however, so you can get a jump start on building your own if you’re looking to warm things up this winter.

Continue reading to see a video overview of the thermostat’s design.

[Read more...]

Building your own replacement refrigerator thermostat

refrigerator_thermostat_repair

[Ron’s] refrigerator broke shortly after he came home from his weekly grocery trip, and since this was his second dead fridge in three years, he wanted to fix it rather than buy a new one…again. It turns out that the thermostat was toast, and a replacement would cost him $80. That was well more than he was willing to pay, but his groceries were starting to get warm, so he had to do something.

Being the tinkerer he is, he figured he could rig up his own thermostat that would work at least as well as the one that died on him. He scavenged an ATmega328 from a failed project, and after digging around online, put together the most barebones Arduino setup he could find. The microcontroller is tucked away in the back of the refrigerator where the old thermostat used to live, and takes input from a TMP36 temperature sensor, triggering a relay to start the refrigerator’s compressor whenever the the temp goes above 4°C.

[Ron] says his fix is just about the “worst kludge ever”, but as he saved $80 in parts and $150 in labor, we’re inclined to think it’s a job well done.

Server room light and temperature monitoring

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[Jaren] is occasionally forgetful, and frequently wonders if he’s left the lights on in his server room. Not knowing if the lights have been left on drives him nuts until he returns to work the next morning, so he decided he had to do something. He figured it would be easy enough to build a small sensor that would allow him to monitor the status of the overhead lights, but he didn’t want to have his micro controller’s abilities go to waste by performing one simple task. Instead, he laid out plans to add an array of other sensors which will allow him to monitor the room’s temperature, sound levels, as well as the current draw of the servers.

Right now the project is in the beginning stages, but he already has part of his sensor network established. He hooked up a TMP421-based temperature module along with a TEMT6000 ambient light sensor to his Arduino, which displays the data on a small LCD screen he purchased. More sensors are on order, so we should expect to see more progress in the coming weeks.

Hopefully when everything is completed we will see a full set of schematics and code so that anyone can buld their own server room monitoring network from his designs.

Rule your furnace with this network-enabled thermostat

diy_thermostat

Adafruit forum member [Stephanie] embarked on a mission to replace the thermostat in her home with one that was far more robust and full of electronic goodies.

Her goal was to build a networked thermostat that allowed for 2-way communications between the base station and any other networked device, such as her laptop or iPhone. She wanted to not only be able to monitor her furnace and air conditioning systems remotely, but to control the units from afar as well.

The brains of the thermostat have changed throughout the project, becoming simpler as time went on. It is now controlled with just an ATMega328 mounted to the back of an LCD display with a Wiznet network module where an Adafruit Ethernet shield used to reside. The thermostat shows the current temperature, set temperature, and time on the front mounted LCD, the latter of which is provided by a Chronodot module. It also has an on board LED that can be seen from afar, indicating whether the heat or air conditioning is running,

Right now the thermostat can be controlled at the unit itself, or remotely using a Telnet session. [Stephanie] is currently happy with the setup, but future plans include creating an iPad application to provide a more user-friendly interface.

If you are interested in learning more, or building one yourself, be sure to swing by her blog for a far more in-depth look at the build process.

Thermostat Controlled Plug Box

[Eric] has a problem with his new house, there was no heat in the attic space that had been converted into a loft. Facing no way to tap into the ductwork and wanting to use the space as a bedroom he did what most of us would, and just got a little space heater. Anyone who has lived with a space heater knows you have to be around to turn them on, and they usually dont have decent temperature control. These problems were quickly fixed by making a thermostat controlled plug box.

A quick trip to the hardware store resulted in a 2 gang metal junction box, faceplate with GFCI cutout, receptacle and a Honeywell baseboard heater thermostat. The thermostat is then wired to mains and its output connects to the receptacle.

He gives instructions on wiring which focuses on his parts, but you should follow the instructions to your specific thermostat, and error on the side of caution if working with mains current. The end story is a bedroom with a more constant temperature and doesn’t need a 3 hour burn to get there.

Super simple Arduino setup lowers electricity bills

An Arduino with 40 lines of code, a temperature resistor, and servo are all that’s truly needed to save some dough with this thermostat by [Peter Hamilton]. LEDs and a potentiometer are added as well to help set and read the desired temperature. With or without said additional parts, the hack is still ridiculously simple and we’re wondering why we didn’t have a similar setup on our blisteringly cold office AC system before seeing it.

Though, we’re going a bit further with our version, plans are in the making to add timers to turn off the system for extended hours while no one is at the office. What would you add?

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