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136  Using Arduino / General Electronics / Re: Voltage regulator help on: September 13, 2013, 07:15:48 pm
Buck converters are strange things to many people.
Heres a good simple explanation of how they work.
http://www.ecircuitcenter.com/Circuits/smps_buck/smps_buck.htm

And yes, the Inductor is a critical part of the converter.
So is the catch diode which you cant see because its inside the IC
137  Using Arduino / Sensors / Re: is there anyway to make smaller antenna for FPV system ? on: September 13, 2013, 04:18:07 am
Its not possible to make the antenna smaller without adversly affecting the range.
Depends on how far you want to transmit.
138  Using Arduino / Motors, Mechanics, and Power / Re: Induction Motor Control through PWN of arduino on: September 07, 2013, 07:28:55 am
Not possible with PWM.
You can vary the speed of a 3 phase induction motor with a VFD (variable speed drive) that you control with the Arduino.
If its a single phase capacitor start induction motor, you cant vary the speed at all.
139  Using Arduino / Networking, Protocols, and Devices / Re: 433 RF question. on: September 05, 2013, 06:20:16 pm
If you dont want to use 2 mcus, its possible to use dedicated hardware such as SC2262,SC2272 encoder / decoder chips
with those radios to send simple 4 bit logic states from one location to another.
This method is designed for applications where a simple button press is all thats needed, and the decoding process is slow.
Can take a few 100 ms to decode the data.

140  Using Arduino / Networking, Protocols, and Devices / Re: 433 RF question. on: September 05, 2013, 08:26:36 am
Those cheap 433 Mhz radio modules wont simulate a hard wired connection, so you cant easily send serial data thru them without some kind
of data processing, which is what The Virtualwire library does.
141  Using Arduino / Project Guidance / Re: RF 433mhz. Missing antenna? (lots of junk receiving) on: September 01, 2013, 05:38:51 pm
There are 2 types , normal superhets and super regenns.
Its hard to tell from looking at them which they are , but yes, the super regens do radiate quite a bit and can interfere
with other receivers in the vicinity.
142  Using Arduino / Project Guidance / Re: Hacking devices with Saw resonators instead if IR transmitters on: August 31, 2013, 12:38:57 am
That video shows an Arduino transmitting  using a 433 Mhz ASK Transmitter.
The Transmitter has a SAW resonator on it , to determine the frequency, usually 433.92 Mhz
but it also has additional electronics on the same little board to actually generate the RF.
The SAW resonator only sets the frequency.
A SAW resonator by itself does nothing.
143  Using Arduino / General Electronics / Re: Bluetooth and Arduino Electromagnetic interference question on: August 30, 2013, 08:59:49 pm
Is the whistle you are hearing around 1.6 Khz.
If so, this is the chirp rate that Bluetooth uses, and it will be the same for any Bluetooth device.
Blueetooth uses  frequency hopping technology which means that the 2.4 Ghz transmitter is pulsing on and off at the
chirp rate.
144  Using Arduino / Project Guidance / Re: Hacking devices with Saw resonators instead if IR transmitters on: August 30, 2013, 08:54:43 pm
Bit of confusion here.
A SAW resonator is a passive device that looks like a high Q frequency determining network.
It behaves in a way similar to a crystal, but can work at much higher frequencies.
A SAW resonator doesnt create RF , you still need extra electronics to do that.
145  Using Arduino / Sensors / Re: DHT11 and humidty, whats the extent of the problem? on: August 29, 2013, 06:27:26 pm
There are accurate humidity sensors.
Here is one.
http://www.sensirion.com/en/products/humidity-temperature/humidity-sensor-sht25/
They are not cheap though, $50+.
146  Using Arduino / Project Guidance / Re: How to make a robot follow you? on: August 29, 2013, 02:27:18 am
It depends on how far behind you , you want the robot to follow.
If its very close, like a meter or 2 , then some simple kind of proximity sensor on the robot that senses
something which you carry will work.
If its further away, it gets much harder, especially if you want the robot to be able to follow you around obstacles
or around a corner.
147  Using Arduino / Project Guidance / Re: Nation Crossing Quadrocopter? on: August 24, 2013, 09:56:35 pm
I suggest you join a RC group that specialises in building quadcopters and learn a lot about
power budgets, ie how much power is needed to lift a given weight.
As a very general rule , you need around 1 watt per ounce of weight.
Unless you can source Solar panels that weigh far less than 1 oz per watt
then you cant use Solar power.
148  Using Arduino / Project Guidance / Re: Nation Crossing Quadrocopter? on: August 24, 2013, 08:13:16 pm
Not a hope in hell.
Have a look at the power consumption of your average quadcopter.
Mines a relatively small one , but the 4  motors pull 6 amps from an 11V lipo battery and
Im using pretty good batteries, and that gives me about 10 minutes flight time.
My quadcopter weighs around 400 grams.
With the best batteries you can buy, you can push the limit to around 20 minutes, but thats about it so far.
You would have more chance with an electric powered plane , but even then it would be pretty big.


149  Using Arduino / General Electronics / Re: General Wireless Module Question on: August 24, 2013, 06:36:14 pm
The tranmsitter is simply a keyed oscillator, whose frequency is set by a saw resonater.
When you apply a logic 1 to the data pin , it produces an output at whatever frequency the saw filter is .
Usually 315 or 433.92 Mhz.
So data gets sent by rapidly turning the transmitter on and off.
As MarkT indicates, they are very simple and crude devices, but can be used successfully with the Virtualwire library
which does all the hard work in coding the data in such a way as to get the best results from them.
150  Using Arduino / Project Guidance / Re: Replicating an RF remote signal on: August 23, 2013, 06:37:52 pm
If the transmitter in the remote uses ASK (amplitude keying) you will be able to receive the data on your 315 Mhz receiver.
Unfortunately, thats the easy part.
Figuring out what it means is the hard part.
Without a CRO or logic analyser it will be very hard to go any further, unless you can somehow find out the data format the remote uses.
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