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31 votes
Accepted

Where can I harvest energy in my home to power my wireless sensors?

DOORS!!! I don't know if it is in the scope of your question but you can't imagine the wasted energy of opening/closing a door! A French comic strip named Gaston Lagaffe written in 1970 introduced a ...
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26 votes
Accepted

Is there any advantage in encrypting sensor data that is not private?

Absolutely, because: A secure device and channel means that you can trust the data. Yes, the actual temperature is not very private, but an attacker can provide false temperatures and cause an ...
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21 votes

Where can I harvest energy in my home to power my wireless sensors?

Solar energy is even indoors an alternative to thermal and vibrational energy harvesting. This indoor photovoltaics use both the natural light and artificial light. On the Feasibility of Indoor Light ...
  • 2,449
16 votes

Battery backup for small IoT devices?

You can hook up a USB battery pack to both the Pi and the charger (as long as it is designed to charge while being used) and if the power goes out the USB battery pack will take over powering the Pi ...
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14 votes

Where can I harvest energy in my home to power my wireless sensors?

While having so much valuable answers to my question I have also done some further research about the topic. I have found an additional harvesting solution and also a great reference design about a ...
13 votes
Accepted

Temperature sensors affected by rain

A wet sensor will not measure the same temperature as a dry sensor due to the evaporation of water from its surface and with the required latent heat being supplied by the sensor, i.e. evaporating ...
  • 2,449
13 votes
Accepted

Measure people density in an outdoor area

In a comment to the original question, the OP suggests that an accurate count of people might not be needed, but the goal is rather to be able to detect an unusual amassing of people in an area. This ...
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11 votes

What are affordable solutions to air quality monitoring system?

I think it's non-existent today. I work at a Dutch municipality and, though things might have changed now, in December 2017 our environmental department concluded that even semi-professional gas or ...
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10 votes

What is the power implication of encrypting my sensor traffic?

There are a variety of encryption methods you could use to secure your traffic, and each one has a slightly different power usage, so I'm going to pick a couple of popular choices. The methodology I ...
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10 votes
Accepted

Will multiple simultaneous biometric sensors create unbreakable security for devices?

The technical answer to is this security unbreakable? is "no". The primary reason is that biometric attributes are not secrets. Some are easily duplicated, like fingerprints, or images of faces. ...
  • 2,422
10 votes

Where can I harvest energy in my home to power my wireless sensors?

This is an idea I've had that I'll throw out here... It seems like it should be possible to have a small device that you simply wrap a mains power cord around a few times (or wrap the device around ...
  • 201
10 votes

Speed limitations on moving sensors

Reliable communications between digital devices requires some degree of signal processing to synchronize the data and the timing (clock). Adding relative motion between the transmitter and receiver ...
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9 votes
Accepted

Wired sensor protocol for buildings monitoring sensors?

I would either go with RS485 or CAN because with long buses a lot of noise can be picked up. These are the most noise resistant as both of them use differential, twisted data lines. RS485 supports ...
9 votes

Battery backup for small IoT devices?

If possible choose a device that has a built in battery. A few such examples that use the common 2-pin JST connector. The first two are based off of the esp8266 WioLink WioNode C.H.I.P ($9 computer)...
  • 551
9 votes

Where can I harvest energy in my home to power my wireless sensors?

Radiators should be a source of vibration (driven from the pump), though you would probably need to investigate the resonance frequencies quite carefully. It is also possible to embed kinetic energy ...
9 votes

Where can I harvest energy in my home to power my wireless sensors?

WiFi signals Forget about stealing your neighbor's Wi-Fi to surf the internet. Using cheap everyday materials, researchers at Duke University’s Pratt School of Engineering have developed a remarkable ...
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9 votes

Where can I harvest energy in my home to power my wireless sensors?

This is a great idea to harvest energy from our daily energy use. But you have to consider that the energy you harvest comes from somewhere. If you want to harvest some heat from your room heating ...
  • 338
9 votes

Automatically open a garage door when approaching by car?

As noted by Sean Houlihane in a comment, you're looking for geo-fencing: A geo-fence is a virtual perimeter for a real-world geographic area. [...] The use of a geo-fence is called geo-fencing, and ...
  • 18.1k
9 votes
Accepted

Automatically open a garage door when approaching by car?

I'd go for OwnTracks (iOS + Android) which lets your phone send GPS-data over (preferably MQTT) the internet. You may set up this to poll your phone and let a server see if the signal is approaching ...
9 votes

Temperature sensors affected by rain

Building upon several years of deploying outdoor wireless sensor networks, I would like to add the following hint: Think ahead and do not underestimate the problems arising from humidity! I will ...
  • 649
9 votes

Power reduction for Raspberry Pi GPS/GSM tracker

I'll assume that the processing requirements on the device are near enough zero. It sounds like you're using some acceleration input to determine how often to wake up the GSM device. Ideally, you ...
9 votes

What are some good tools for graphing sensor values?

InfluxDB in Domoticz This is a database provided with the Domoticz installation on Raspberry Pi. It allows to use data with time series. Domoticz uses this to modelize sensors' data
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8 votes
Accepted

What is the power implication of encrypting my sensor traffic?

The bulk of your power will likely be expended on RF transmission, not CPU cycles spent in encryption routines. Every additional bit transmitted will cost you more power than the encryption you're ...
  • 2,422
8 votes

Is there any advantage in encrypting sensor data that is not private?

Sensor reports to a current thermostat reading feel very private to me. A burglar could use the data to find out when a person is at home. After the house got robbed the owner might decide it's a good ...
  • 685
8 votes
Accepted

Using LP Gas Sensor in a Smart Home Safety System

Regarding the humidity and temperature there are the following specifications that should be match: Problems will start above 50 °C and 95 % humidity. But below, it should be fine. The standard ...
8 votes

Using LP Gas Sensor in a Smart Home Safety System

I've not used one of these sensors, but looking at the quoted sensitivity, it would be best placed as close as possible to the source of a leak, or at a low point (many flammable gasses are denser ...
8 votes
Accepted

Repurpose ADT sensors

That particular sensor is using RF 345 MHz and is not compatible with SmartThings. To connect the sensor directly to the SmartThings hub it would to be Zwave, Zigbee, or Lan Connected; it would also ...
8 votes

Where can I harvest energy in my home to power my wireless sensors?

An exercise bike/ treadmill rigged to a dynamo. This will also give you an incentive to work out. Rather than using the microwave oven/convection oven which will eat into their function, you can ...
  • 181
8 votes

Where can I harvest energy in my home to power my wireless sensors?

One often available temperature differential that might be harvested would be: the difference between internal house temperature, and external. With a temperature controlled living environment, ...
  • 181
8 votes

Measure people density in an outdoor area

There are plenty of methods of people counting that could be useful, depending on your exact use case. If you want to measure the amount of people entering an area... you might want to consider an ...
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