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121  Using Arduino / Project Guidance / Re: Lowest power method for 2 digit LCD on: March 27, 2014, 06:03:00 pm
Have a look at one of these.
http://ww1.microchip.com/downloads/en/DeviceDoc/41250F.pdf
Inbuilt LCD driver which runs even when the Micro is in sleep mode..
122  Using Arduino / General Electronics / Re: Serial communication question on: March 25, 2014, 07:56:00 pm
Try sending the data slower, lower baud rate , or leave a pause between the characters being sent.
Software Serial doesnt have a receive buffer, so data can get corrupted if data is coming in , but the CPU is doing something else
like writing to a display.
123  Using Arduino / General Electronics / Re: Wireless sound from one arduino to another on: March 24, 2014, 01:41:58 am
This is by no means a trivial project.
You will need some kind of audio amplifer which also provides a Dc offset so that the microphone output
falls within the range of the Arduinos A/D converter.
You will also need some kind of simple audio codec to convert the sampled audio into a digital bit stream to feed to the radio.
At the receiving end you will have to do the reverse, and then somehow recover the audio and feed it to an audio amplifier and then a speaker.
Hope you are an experianced Arduino programmer.

124  Topics / Device Hacking / Re: car fm radio antenna hack on: March 21, 2014, 12:36:03 am
AM means Amplitude Modulation.
FM means Frequency Modulation.
In either case, you need some hardware that can function as a modulator.
The Arduino cant, as theres nothing in it that can perform this function.

125  Using Arduino / General Electronics / Re: AC Freq Measurement on: March 18, 2014, 07:00:08 pm
How accurately do you want to measure the frequency?
Thats what determines the complexity needed.
126  Using Arduino / Networking, Protocols, and Devices / Re: Making a wireless transceiver on: March 18, 2014, 12:51:55 am
Its not generally viable to build your own radio tranceivers.
You need specialised test gear that most people dont have, and its far easier to simply buy
the assembled radios.
127  Using Arduino / Project Guidance / Re: RF Transmitter Not Working on: March 17, 2014, 02:43:56 am
Im still trying to understand what the LM386 does, given that its an audio amplifier.
128  Using Arduino / Project Guidance / Re: RF Transmitter Not Working on: March 16, 2014, 12:27:07 am
What you have built isnt a transmitter.
To generate 136 Mhz at sufficient power to light the globe, you need a stable frequency source, usually a crystal oscillator.
You then need a series of frequency multiplier stages to multiply the crystal frequency up to 136 Mhz, and then an RF power amplifier to raise the power level sufficiently to light the globe.
None of this is easy stuff for a first project.
If you really want to learn how to build transmitters, then this book is a good place to start.
http://www.arrl.org/arrl-handbook-2014
Be warned though, its a steep learning curve.
129  Using Arduino / Project Guidance / Re: RF Transmitter Not Working on: March 15, 2014, 05:39:40 pm
This type of experiment needs a substantial amount of transmitter power, at least 5-10 watts, and both the
transmitting and receiving antennas must be resonant with the transmitters frequency.

130  Using Arduino / Project Guidance / Re: Arduino + PIR + ATX Power Supply + LED Light Strips on: March 12, 2014, 10:40:11 pm
Theres nothing wrong if you dont need a regulated supply.
The 12V rail will vary depending on what load you connect to it, It will be low , ie less than 12V , and its not easy to know how much power it will supply before you cook the diode bridge for that rail.
If you keep the total power demand well below the supply maximum rating, say half its rating, it will work OK.

131  Using Arduino / Project Guidance / Re: Arduino + PIR + ATX Power Supply + LED Light Strips on: March 12, 2014, 01:05:26 am
More information is needed about what voltage and current the leds need.
ATX power supplies only directly regulate the 5V rail, and the 3.3 and 12V rails are indirectly regulated,
but need a load on the 5V rail for any regulation to work at all.
Because the supply is rated at 280W doesnt mean it can supply 280W on a single rail.
The power rating is the sum of all the rails added together in the typical proportion that a computer motherboard  needs.
If you want to use just one of the supply voltages, and not the others and want the one voltage regulated, you will have to modify
the supply and change the values of the sense resistors that control the PWM to the primary switcher.
Unless you have had previous experiance at doing this , I wouldnt use an ATX supply.


132  Using Arduino / General Electronics / Re: Line voltage (0-177v) variable power supply, feasible? on: March 10, 2014, 05:24:18 pm
You will still need a transformer.
The only differance is that instead of using a iron core transformer you will need a ferrite core transformer.
Such a power supply is feasable, but it sure isnt a beginners project, and a real lot can go wrong.
I would get some experiance in building small lo power switch mode power supplies first.
Theres a lot of math involved in building switch mode supplies that has to be well understood, otherwise you will end up
with a lot of dead fets.
133  Using Arduino / General Electronics / Re: Smallest DC-DC converter? on: February 25, 2014, 12:26:18 am
Whats is supplying the 5V?
USB ports are limited to 500ma , and some in laptops can only supply 100 ma.
You may find the DC - DC convertor wont start.
134  Using Arduino / General Electronics / Re: To supply power to Arduino WI Fi sheild Using 9V Battery on: February 23, 2014, 05:43:03 am
how long do you want the batteries to last
WiFi shields are power hungry,drawing around 130 ma on both receive and transmit.
Those little 9v batteries went last long,even if they work at all.
You need a bigger battery like a 7.4v lipo battery,or a 12v sealed lead act battery.



135  Using Arduino / Project Guidance / Re: Large Radio Network ? on: February 21, 2014, 04:55:23 pm
Powering the radios could be a problem, depending on how long you want the batteries to last.
If the radios have to be listening all the time, that represents a sizeable power component.
What sort of batteries are you going to use.
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