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166  Using Arduino / Motors, Mechanics, and Power / Re: Using LiPo Fuel Gauge for reading THIS! battery pack on: October 12, 2013, 03:58:16 am
Dont confuse precision with resolution.
The Arduino can read to a resolution of 4.9 mv , but that doesnt mean its accurate to 4.9 mv.
Its accuracy is set by the accuracy of whatever its using as its voltage referance.
167  Using Arduino / Project Guidance / Re: Energy monitor on: October 12, 2013, 03:50:11 am
How big are the batteries and how are they wired. (series or parallel).
A 1100 watt Inverter can pull close to 100 amps from a 12V battery and this will rapidly deplete the battery.
You need some idea of how much energy is going to be consumed each day.
168  Using Arduino / Project Guidance / Re: Radio direction finder on: October 11, 2013, 01:14:15 am
The voltage by itself isnt enough to get direction.
You also need to measure the phase angle between the 2 RF signals from each antenna to get the quadrant info.
169  Using Arduino / Networking, Protocols, and Devices / Re: Arduino RF communication problem on: October 10, 2013, 05:56:29 pm
Why dont you want to use Sc2262 Sc2272 devices.
They will do exactly what you want.
170  Using Arduino / Project Guidance / Re: Best Arduino wireless communication solution - 350Mhz / 433Mhz / 950Mhz / 2.4Ghz on: October 10, 2013, 12:17:17 am
What do you mean by module?
Are you just talking about Transmitters, or Transmitters and Receivers.
The power consumption of them all is totally dependant on how much of the time they are transmitting.
The receivers need to be running all the time , and they are relatively power hungry.
Basically, the bottom line is the power consumption is proportional to the range you need.
Do you need full duplex or half duplex transmission.
Do you need inbuilt error correction.
Without any understanding of your needs , its impossible to answer.
171  Using Arduino / General Electronics / Re: how do 2.4 Ghz transmitters work on: October 03, 2013, 01:10:31 am
Not sure I fully understand your question, but this is how the 2.4 Ghz frequency is generated.
 The 2.4 Ghz transmitter frequency is generated by a voltage controlled oscillator which feeds
a very hi frequency divider called a dual modulus prescaler.
This chip divides the 2.4 Ghz signal down to a much lower value where its compared with a similar value from a conventional crystal oscillator using a phase detector.
The phase detector produces a variable output DC voltage which controls the frequency of the 2.4 Ghz oscillator.
This gives a stable frequency at 2.4 Ghz which equals the stability of the crystal oscillator used to do the comparison.
172  Using Arduino / Project Guidance / Re: Replicating an RF remote signal on: September 30, 2013, 11:00:49 pm
Its important to not confuse learning remotes that work with IR , with those that work with RF.
Its dead easy to learn what the output of an IR transmitter is simply because the only transmission you will see
coming from the IR receiver is your own.
With RF, there will be stuff coming from the receiver all the time, even when you arnt transmitting,so the receiving code
needs to be able to sort out the garbage from the wanted data.
173  Using Arduino / Networking, Protocols, and Devices / Re: 433MHz Simple RF Link Kit on: September 30, 2013, 05:30:24 am
No, the Virtual Wire library uses Manchester Coding which has inherant error detection in it .
You either get the correct result or in this case, you wont get any data output.
And thats the other issue, if both transmitters transmit at once , neither transmission will be received.
If its necessary to have to separate radio channels in close proximity, then you need 2 separate radio channels
which could be done by using both 433 and 315 Mhz radios.
174  Using Arduino / General Electronics / Re: Ambient radio wave energy on: September 30, 2013, 05:03:44 am
This is difficult to do.
Whilst there is a lot of radio frequency energy being transmitted from multiple radio transmitters all around
its simply not possible to somehow add it all together and generate any power.
This is because its all AC and the phase relationships of all the transmissions are not related to each other in any way.
This simplest way and the most likley is the humble MF crystal set, consisting of a simple tuned circuit to isolate a single
transmission, a diode to rectify it , and a capacitor to charge.
But dont expect to get much energy, unless you live across the road from a 50+KW transmitter.
The longer the antenna the better, and long wire antennas work well with MF broadcasting stations.
The single largest source of radio noise is the Sun, but its totally useless as its non coherant so the energy is spread
across a wide bandwidth.
175  Using Arduino / Project Guidance / Re: Powering Uno with LiPo and solar panel on: September 27, 2013, 04:47:22 am
These types of questions cant be answered unless the power consumption of the Uno is known.
Will the Uno and the WiFi shield be running all the time , or just for a few hours a day?
176  Using Arduino / Project Guidance / Re: connecting solar panel? pv datalogger. measure voltage and current on: September 23, 2013, 01:31:42 am
What exactly is the aim of the project?
Are you trying to measure how much energy the solar panel makes over some period of time
or just how much power the solar panel makes into some random value resistor?
Ideally, to measure how much energy a solar panel can make over some time frame , you need
some kind of MPPT tracker, but thats probably not what you had in mind .
177  Using Arduino / Networking, Protocols, and Devices / Re: Looking for a simple wireless "switch" on: September 20, 2013, 06:20:02 pm
You need at the transmitting end some kind of data processing device , either an encoder or a small MCU.
As you previously indicated you had trouble sourcing the SC2262 encoders, then the next option available is
a small Micro at the transmitting end, which is what the ATTiny is for.
Its important to understand that the simple transmitter / receivers by themselves cannot simulate a hard wired link.
Also, you arnt the only person in the world who uses these simple transmitter / receivers, so you must have some way
of identifying your transmissions from any others that your receiver will pick up.
For most people who use these devices , the virtualwire library which needs to run in an Atmel based Micro and does all the hard work for you
is the easiest way.
Note that you will still need to do some basic programming of the Micros at both ends to make this work.
178  Using Arduino / Motors, Mechanics, and Power / Re: Driving a Car Alternator as a Motor on: September 20, 2013, 02:21:52 am
Car alternators are 3 phase with a full wave diode bridge to produce the DC.
The only way to run one as a motor is to supply 3 phase AC at whatever frequency you want the motor to run at.
Its possible but a lot of work, and needs specialised electronics.
179  Using Arduino / Networking, Protocols, and Devices / Re: Looking for a simple wireless "switch" on: September 19, 2013, 08:13:43 pm
If sourcing the encoder / decoder chips is difficult, then you can use something like an ATtiny at the transmitting end.
You will need to use the Virtualwire library at both ends to handle the data encoding for the Transmitter and Receiver.
https://www.sparkfun.com/products/10532
https://www.sparkfun.com/products/10534
https://www.sparkfun.com/products/9378



180  Using Arduino / Networking, Protocols, and Devices / Re: Looking for a simple wireless "switch" on: September 18, 2013, 06:27:46 pm
Use an SC2262 encoder at the push button end, and a SC2272 decoder at the Arduino.
These devices are designed for the transmitting of momentary information and can handle 4 bits, ie
setting 1 or more bits high or low at the transmitting end , causes the equivalent bits at the receiving end to change.
You also need a cheap transmitter and receiver.
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