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226  Using Arduino / General Electronics / Re: Run motor from rc helicopter through Arduino on: August 18, 2013, 11:30:04 pm
If you want the helicopter to fly, you need to test the motor with the helicopter rotor attached.
Helicopter motors draw amps , not ma , which is one reason that model helicopters use lipo batteries.
Model helicopters also have ESCs on the control board to power the motors.
You need to use the hardware in the helicopter to power the motors.
It may be possible to use the arduino to control the ESC in the helicopter to control the motor speeds.
If you know the AH capacity of the helicopter battery , and the average flight time , you can work out
the average motor current.
227  Using Arduino / Networking, Protocols, and Devices / Re: 433 MHz RF problems - can't even get test program to work on: August 18, 2013, 05:32:32 pm
Possible that you have the receiver too close to the transmitter, causing it to overload when the transmitter transmits.
Try a minimum spacing of a few metres.
228  Using Arduino / Networking, Protocols, and Devices / Re: 433MHz transmiter for radio control on: August 17, 2013, 09:46:44 pm
Most of the small cheap radios are range limited because of the way they work.
The transmitters are power limited and the receivers are broadband.
This allows them to be used very easily, to be able to cope with multiple data rates
and makes them ideal for short range applications like garage door openers etc.
The 2.4 Ghz radios wont penetrate solid objects very well, and the 433 Mhz radios are too low powered
to get any decent range.
You could theoretically get to around 1 Km with high efficiency gain antennas at both ends, but thats not really
viable for model control.
229  Using Arduino / Project Guidance / Re: Get rid of PWM noise in brushless fan on: August 15, 2013, 12:05:50 am
What kind of fans are you using.
Brushless DC fans commonly used in PCs cant be speed controlled, unless they are specifically designed to be .
In which case the fan will have 4 wires going into it.
Supply voltage + - and speed detection and speed control.
Trying to PWM the supply voltage will simply destroy the internal electronics in the fan over time.
230  Using Arduino / Project Guidance / Re: USB Serial handshake problems on: August 13, 2013, 07:28:42 pm
Most PCs will support Xon - Xoff flow control, although you have to turn it on .
Some info here.
231  Using Arduino / Networking, Protocols, and Devices / Re: XD-RF-5V receiver and RCSwitch problem on: August 13, 2013, 06:09:20 pm
The RCswitch library is designed to decode transmissions from devices that use the SC2262 encoder chip.
If your garage door opener doesnt use this chip, then you wont decode anything.
Most garage door openers use rolling code transmitters to provide extra security, and dont use the SC2262 chips.
232  Using Arduino / Project Guidance / Re: Using a Satellite Dish in Projects on: August 12, 2013, 05:55:03 pm
Not much you can do with the dish Im afraid.
They are specifically designed for just one purpose and the electronics that comes with them
is usually just a low noise down converter which needs a special receiver to work.
If you had 2 dishes and lots of spare money, you could make yourself a microwave data link
but thats not a beginners project.

233  Using Arduino / Project Guidance / Re: How to build an suitable RF antenna for Receiver/Transmitter? on: August 12, 2013, 02:56:18 am
Its not essential to have a ground plane if you have the right kind of antenna.
A end fed 1/2 wave antenna doesnt need a ground plane .
These types of antennas are used on some cars as on glass type antennas where one end of the antenna
is simply stuck on the glass, and a small coupler is stuck on the other side.
The tricky bit is making the coupling circuit to drive the antenna from one end , as a end fed 1/2 wave
presents a high impedance feed.
Some of the rubber ducky types can be like this with the coupling circuit on the base and a loading coil
in the antenna proper so that its overall length is reduced to a manageable length.
234  Using Arduino / Networking, Protocols, and Devices / Re: Arduino and 315/433 MHz Wireless PIR Sensors on: August 08, 2013, 07:03:53 pm
What information do you have about the sensors?
To do what you want, you will need to determine what the data format is that the sensor sends.
This isnt an easy task.
If you have a CRO, then pulling a sensor apart and trying to find the data line to the internal transmitter
would be a good start.
235  Using Arduino / General Electronics / Re: Can I use 4.7K pullup with DHT22 sensor? on: August 08, 2013, 06:51:11 pm
The strength of the pullup resistor thats needed is largely determined by how long the cable is between the Arduino and the sensor.
The longer the cable , the lower the resistor needs to be.
The sensor sends data is the form of pulses, 28 us long and 70 us long, and as long as the rising and falling edges of the pulses are square enough to read
the sensor will work OK.
Ive got some sensors on 3 metre cables with 10K and they work fine.

236  Using Arduino / General Electronics / Re: Can I use 4.7K pullup with DHT22 sensor? on: August 08, 2013, 12:15:48 am
The resistor only draws 0.7 ma when the DHT22 is actually measuring.
When its not measuring the resistor draws nothing as the data line is normally high.
What little current the DHT22 consumes is via its power pin, not the data pin.

237  Using Arduino / Motors, Mechanics, and Power / Re: Controlling a 220 volt ac motor on: August 07, 2013, 06:49:46 pm
It totally depends what type of motor it is.
If its an induction motor. then you cant control the speed with a triac.
Induction motors rotate at a speed which is dependant on the supply frequency.
If its a brush type or universal motor , then the triac will work.
238  Using Arduino / General Electronics / Re: Can I use 4.7K pullup with DHT22 sensor? on: August 07, 2013, 06:38:58 pm
DHT22 only draws around 40 ua when not measuring.
Theres no need to disconnect the resistor.
239  Using Arduino / Networking, Protocols, and Devices / Re: Wireless dish on: August 06, 2013, 06:42:14 pm
No hope Im afraid.
The dish is far too small to be able to determine whether a signal is withing 5 degrees.
To get that level of accuracy. you would need a much bigger dish.
Something like one of these.

240  Using Arduino / General Electronics / Re: A question about solar panels on: August 06, 2013, 06:20:22 pm
If the Solar panel is very small, its a lot easier to use NIMH batteries rather than LIPOs.
NIMH are a lot more forgiving about overcharge and undercharge.
If you pick a Solar panel with a maximum current output that is less than C/20
of the Nimh battery, then it will happily accept the overcharge.
3 NIMH in series will give you 3.6 v , almost the same as a lipos 3.7 V
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