Energy meter with Nixie tubes

Normally every house has power usage meter where you can see how much power you have used. But sometimes you might want to see how much energy you are currently using and probably trace the devices that are most energy hungry. John decided to instal energy meter next to his power meter. He didn’t want to use LCDs or LED indicators that wouldn’t look great next to meter blown glass face. So he went with Nixie tubes. He used couple of ready made nixie tube modules that already accept 5V and can be controlled via SPI interface. He paired Arduino with ESP8266 module to have good ADC and IoT functionality. He found out that Nixie tubes draw quite some power – 300mA. So he went with only two modules to reduce the overall impact. He made unit indicator that would allow indicating from 0 to 100MW. Only two significant figures are always visible. This is more than enough for rough monitoring. Power is measured with SCT-013 clip-on current transformer which has current sensing resistor. Arduino samples the output and calculates… Continue reading

Maintaining room humidity level

Right humidity level in the room or other area is as important as temperature. Not enough humidity leads to dry climate and overall feeling. Indoor plants may suffer, you sleep quality may drop. In other hand to much humidity could damage materials, have effect on your health. Like everywhere – there should be some balance. In practice human feel better when environment is more humid than dry. Personally for me 50% to 60% relative humidity is best. But not all places naturally have good humidity. Especially when heating season starts, humidity usually drops and you need to thing of ways how to increase its level. Many people use wet towels or other passive ways. Other use humidifiers. __loovee__ from instructables have built his own arduino based automatic humidifier which constantly monitor humidity level and adds some humidity when it drops. He used DHT11 temperature/humidity sensor to detect humidity level. In order to add humidity he used water atomizer which is basically piezo element that vaporizes water. Arduino/Seeduino stores the threshold level which can be changed. He made acrylic enclosure which… Continue reading

Back to basics – pull-up resistors

If you start dealing with microcontrollers, you will definitely face the term ‘pull-up’ resistor. This is not a resistor type, but rather its purpose. As name already states it pulls something up. A1RONZO have written very explanatory tutorial where he goes through almost all aspects of pull-up resistors including typical circuits on AVR microcontrollers, how to calculate its value and how to deal with internal and external pull-ups. If you are just starting to learn interfacing and programming microcontrollers, be sure to read through and understand whey they are there. Continue reading

Keypad based garage door access

Garage is one place that need to be protected but also has to be convenient to access. When driving in and out a remote control is great choice. SamJBoz had a problem with his remote control so he decided to build in a keypad controlled system based on arduino. Keypad system uses 4 digit pin codes for opening lock. Each family member has its own pin code. User with master code can enter and delete new users. Arduino Pro Mini sits on a custom PCB which has necessary connections for keypad, Piezo buzzer, LED and other. Eagle files are available for download. Continue reading

Handy capacitance tester on Arduino

If you are working on capacitance sensitive projects, it is recommended to check capacitor value before use. Practically any multimeter already have capacitance measure mode. If you are not satisfied with its range or want to have dedicated device, consider of building one. Braulio777 have written pretty illustrative instructable where he shares all building steps on how he built cap meter. It is capable of measuring capacitance from 0.000pF 0.001pF to 1000uF. The meter is built around Arduino where external components are assembled on separate Arduino proto shield with 16×2 LCD on top. He run several tests that prove that meter works within specs. With enclosure and battery it becomes decent portable meter. Continue reading

Arduino based weather station with multiple sensors

Weather stations are one of the most common projects around hobbyists. You actually don’t need much to build one. For instance Andre Sentosa put together one of its versions. He took Arduino boards for the brains, then attached a bunch of various sensors including DHT11 humidity and temperature, BMP185 barometric sensor, rain drop sensor and soil humidity. With a bit of code he was able to log data to serial monitor. There are still plenty room for more sensors like LDR, wind speed and so on to make it more advanced. IF you are thinking on getting serious, you should also think about remote data transfer and convenient logging. Continue reading