I'm building a cosplay prop for a friend that uses an arudunio Uno. The UNO will be kept inside a black PVC box with little ventilation and taken to comic cons. So it's going to get hot at times. I've never really built gaming PCs or anything with batteries and I'm not sure what temperatures are ideal to run at so my guesses are just based on a google search.
My question is:
If I place a temperature sensor next to the UNO and program it to start a fan at a given temperature, What temperature would be a good choice?
I was thinking 35 degrees with an alarm going off at 70 degrees telling him to turn it off.
Also, there will be two other batteries one 3.7V Li ion phone battery that powers the chips and a small audio amp with a 18-volt (May change) drill battery powering a DC motor. Both in different locations.
For this, I was thinking I would set a larger fan to start at 30 degrees with an alarm at 55.
FYI this will be programmed on a separate ATTINY chip.
I would recommend keeping it below 125C maximum (that is the ATmega 328p's maximum temperature rating). However, I have never seen an UNO get that hot. If you are concerned though, aim for as cool as possible with a maximum temperature of about 80C
Related
I'm reading so much propaganda about BLE beacons (Kontakt.io, in my case) being accurate to the centimetre, readable at 70 metres etc etc, but my experience has been nothing like that.
I have 3 beacons. If they're in the next room over (door open, around 6 or 7 metres), it'll detect maybe one or two, after around 20 seconds. Even then I often need to restart my app over and over to detect it.
Move them to the same room, and they're pretty much okay. Everything's default, scanMode is 'LOW_LATENCY', scanPeriod is 'RANGING', I'm not sure what else I can do.
Do these results sound way off, or are they just not that good?
A few tips about Bluetooth beacons in general, not specifically Kontakt beacons:
When you need to restart your app to detect beacons, that clearly means it is something on the phone, not the beacons themselves that are the issue. That issue may be the app, the SDK, the Bluetooth stack on the phone, or the phone's bluetooth hardware. Try an off the shelf detector app like BeaconLocate for iOS or Android and also test with a different phone.
The range of a beacon is dependent on its output transmitter power, typically measured at 1 meter. This output power is adjustable on many hardware beacons and is often set lower than the maximum to save battery on battery-powered models. For best detection results, set the output power to the maximum that configuration allows. An output power at one meter should be at least -59 dBm for best results. Less negative numbers mean more power. Because some phone models have poor sensitivity and measure RSSI inaccurately, you may want to measure with different models. In general iOS models are more predictable receivers.
The range of a beacon between rooms varies greatly depending on materials in walls, furnishings, and local geometry. A beacon with an output power of -59 dBm at one meter can be reliably detected by a phone with a sensitive receiver at 40 meters away, but only with clear line of sight conditions (typically outdoors). Intermittently, I have seen such beacons be detected outdoors at over 100 meters away. Intermittently means that 99% of packets are lost, a small percentage are successfully received.
Always be skeptical of marketing claims from companies trying to sell you something. The above points should tell you what is achievable from an independent engineering perspective.
I am using 6 different sensors which are working simultaneously, but I got a problem in the readings from LM35 temperature sensor and MQ-7 Carbon Monoxide sensor. The values are changing depending on the power source.
How can I fix this problem? I'm planning to use a Sony power bank to feed my system but I am getting the wrong values especially from the temperature sensor.
Make sure that your power source is stable and continuous (i.e. make sure that your power bank is working fine and check its current output if its compatible with Arduino)
Make sure that your sensors are wired correct and working fine, try with different LM35 and MQ-7 sensors, if you have that chance.
Make sure that you are supplying your circuit with correct voltage and current, sensors may work unstable if you are supplying them directly from Arduino pins (because maximum current limit of the pins onboard may not be enough for your circuit), try an external power source such as MB102 power module.
Although, it's not a coding problem my suggestion is you can use signal conditioning to solved this. Search about low pass filter and high pass filter to filtering frequency in output sensor.
The simple method is using voltage divider, like this:
Vout = (R1/R1+R2) * Vin
R1 is your sensor, and R2 is resistor.
I'm using a SIM808 GSM+GPS module on a LoNet breakout board: http://www.seeedstudio.com/wiki/LoNet_-_GSM/GPRS/GPS_Breakout with an Adafruit Trinket Pro 3V, and everything works.
I've taken care to build in power save modes in my application. I can enable the SIM808 slow clock, so it can sleep with DTR=1, which I call "light sleep" mode. Also there is a "deep sleep" mode, where I set AT+CFUN=0 to further decrease functionality of the SIM808, and power usage. (During deep sleep the RF circuits are off, so no SMS reception..)
I've measured power consumption by measuring the voltage across a 1 ohm resistor in series with the battery.
During normal GSM operation 19-20 mA is used; with slow clock enabled also 19-20 mA, in deep sleep 18-19 mA.
Switching on GPS makes the board use 43-44 mA. I see no difference while acquiring the GPS fix, or when a fix is reached. The wiki page (above) says that continuous tracking takes 24 mA, but apparently that is on top of the 20 mA when just the GSM is used. Indeed 20+24 is 44 mA, the value I measure.
I'm quite disappointed that the sleep conditions don't seem to save any power!
Should I do things like remove the green power LED? The design drawing shows a 470 ohm R in series, so that could save ca 8 mA?
The board does have a battery charging circuit; could that be responsible for the 20 mA base current? When I power down the SIM808 only ca 0.02 mA is used, so I wonder if there is an external circuit responsible for the 20 mA base current. The SIM808 Hardware Docs spec a power consumption of around 1 mA only! - I wish!
I had the same problem like you but on another board.
As you can see at the top of the board below the right one of the two SMA connectors it says: "Active GPS Antenna". And thats the solution to the problem.
When I disconnected the GPS antenna the current dropped to ~670µA without LEDs and when slowclock (AT+CSCLK=1) was enabled, AT+CFUN=0 and DTR pin was high (eg. 3.3V).
So if you want to really make your SIM808 module low power you have to switch the active GPS antenna off with a PMOS.
This image shows the active GPS antenna circuit of my SIM808 Module.
EDIT:
Damn I don't know how to delete or edit a comment... And I can't post more than 2 links, please go to the next links by yourself:
This wiki page (wiki.seeedstudio.com/wiki/LoNet_-_GSM/GPRS/GPS_Breakout) of the LoNet states that: "GPS Antenna: this is an uFL GPS antenna connector. You can connect either passive or active GPS antenna to it. Active GPS antenna runs at 2.8V voltage."
And the schematic (wiki.seeedstudio.com/images/3/37/LoNet_808_Schematic.pdf) shows in the top right corner, that the GPS connector is prepared for an active antenna (the inductor in series with the current limiting resistor).
So if you don't have an active antenna you maybe can just cut the trace between the inductor and the GPS connector.
I don't know what will happen when you are using a passive antenna, you have to try it yourself.
Good luck!
I have really work on a final year project in 4th year computer science. I need to calculate the blood pressure level of a human in a real time and alert to him.
Do we have any sensors for Ardino or Resbrry PI boards.
I have search on enter link description here but I have seen lots of sensors for heart rate but non of them for blood pressure.
Do you think is there any sensors available to get the blood pressures from ardino or rasberry PI ?
You've got a BIG project ahead of you. Automated blood pressure monitors are expensive medical devices, but I'll get you started.
Take a look at this link and think about the physical functions you must accomplish.
http://homepage.smc.edu/wissmann_paul/anatomy1/1bloodpressure.html
First, you have to build a pneumatic control system to inflate a blood pressure cuff and then slowly deflate it.
Second, you have to build an acoustic monitor to listen for the heartbeat below the cuff and a digital signal processing algorithm to detect the heartbeat.
For the first project look online for small pneumatic pumps and solenoid control valves. You will control these with the Arduino and a power transistor to switch the power on and off.
For the second project you will need to build a microphone and amplify that. You can find plenty of examples of microphones on the Arduino forum. The trick part will be designing the DSP filter to identify heartbeats and then count them. See Simon Monk's book, "Beyond Sketches" for an intro to DSP on the Arduino.
Get started and post some more and I'll check back to see if I can help on specific problems as you go forward.
This is an exploratory question really (I am new to arduino / programing ) but I am curious as to weather an arduino board could be programmed with C++ to automatically control the rate of flow of the pump or fan speed ect. to dynamically control and hopefully improve cooling. In addition to this could the Arduino board support a small LCD screen so that real time temperature readouts could be given (I plan to have numerous temperature sensors placed on components?
Thanks.
Yes this does seem feasible. The challenge here might be the temperature measurement. Many of the cheap temperature/humidity sensors that are used with the arduino are actually very slow to register changes in temperature. You may want to do some research on this. Luckily you can do some experiments with temperature measurement and an arduino pretty simply, taking the output of the temperature measurement on the arduino IDE serial console.
The LCD, pump and the fan control is a are pretty widespread and it should be easy to find documentation on those.