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1  Using Arduino / Sensors / Re: Measurement of DC current with non invasive method on: Today at 02:51:29 am
There are 2 types of clamp meters.
The cheap and nasty ones are simply a current transformer and only work with AC.
The better ones that will measure both DC and AC have a calibrated Hall Sensor, but are also more expensive.
2  Using Arduino / General Electronics / Re: ADC false readings on: Today at 02:40:21 am
Could be noise on the opamps output.
What gain does the opamp have , and what is it amplifying.
3  Using Arduino / General Electronics / Re: Wind generator for 12v battery - no controller? on: July 22, 2014, 06:44:41 pm
Have you measured the wind speed at the location where you want the power generated.
Small wind turbines or wind generators are usually almost useless for generating reliable power
as the wind speed never gets high enough to spin the generator fast enough.
You would be far better off with a small solar panel.
4  Using Arduino / Motors, Mechanics, and Power / Re: Use computer PSU for high-amperage LED RGBW on: July 22, 2014, 01:46:05 am
If you are only loading the 12V rail, and none of the others, especially the 5V rail, the PSU wont regulate properly
and may be shutting down due to the 5V rail going hi.
Ive never seen an old computer PS with a 500 W 12V rail.
Whats the total power capacity of the PS.
5  Using Arduino / Networking, Protocols, and Devices / Re: Connecting 3g modem with arduino on: July 20, 2014, 07:44:35 pm
What you are trying to do is possible but quite difficult.
You need a USB host shield to talk to any kind of USB device.
The difficulty will be in finding out what the USB modem expects to see
from the host controller.
You wont find any 3g modems that have normal serial pins , they are all USB.
6  Using Arduino / Project Guidance / Re: RF module query on: July 17, 2014, 12:27:22 am
In short the answer is no.
Some radio transmission technologies , such as CDMA which is used by the mobile phone system can do what you want
but its beyond the scope of the hardware that you want to use.
What is the application that requires so many transmitters and 1 receiver?
7  Using Arduino / Project Guidance / Re: RF module query on: July 16, 2014, 06:27:40 pm
Those simple receivers have no ability to receive multiple transmissions at the same time .
Depending on the relative variations of the incoming signal strengths, the receiver may receive one transmission
but not the other, or more likely, it will receive nothing at all.
If you want to use multiple transmitters with one receiver, the transmitters must be synchronised, so that only 1 is transmitting
at any one time.
8  Using Arduino / Networking, Protocols, and Devices / Re: Strange behavior of rf 433mhz modules in simple transmitter Receiver circuit on: July 07, 2014, 06:04:58 pm
How far apart are the modules?
The 433.92 Mhz band is highly congested, and can easily be interfered by other devices also using the
same frequency.
Its best to send your data multiple times to make sure that some of it is received.
9  Using Arduino / Project Guidance / Re: Can an Arduino be powered by a Rochelle Salt Crystal? on: July 06, 2014, 08:18:20 pm
I built one , and they do work , for a while until the potato dries out , and you need to replace it.
Potatoes are most likley cheaper than rochelle crystals.

Begs an interesting question .
Is potato power = renewable energy?

10  Using Arduino / General Electronics / Re: Can a 12V solar panel charge a 12V battery? on: July 05, 2014, 09:31:34 am
What are the actual specs for the Solar panel?
You need the V/I curve , as its common for 12V panels to actually be 18V panels, with no load.
In which case, you can charge a 12V battery.
11  Using Arduino / Networking, Protocols, and Devices / Re: Please, I am looking for a code to continuously transmit with NRF905 module on: July 04, 2014, 07:02:17 pm
Why do you want to measure the frequency?
Its a GFSK modulated radio, your frequency counter wont make much sense of it.
12  Using Arduino / Sensors / Re: Aurel RX 4MM5 433mhz Receiver on: July 01, 2014, 03:51:00 am
Try using this application.
Im running it on a Uno with a mix of V2 and V3 Oregon Sensors.
Works fine.

13  Using Arduino / Project Guidance / Re: RF Wakeup - Low powered receiver on: June 30, 2014, 06:19:39 pm
There are none , and its because of the need for hi frequency oscillators in them that sadly consume
lots of power.
The best you will find is around current draw of 4 ma @ 5 V.
There are some tricks that you can use however to enhance the battery life.
If you are able to time the transmissions , you can keep the receiver powered off until
it expects to receive something, and then turn it on for a very short period.
Alternatively, power the receiver on and off with a 10% duty cycle.
This then means that any transmission has to transmit for long enough, so that part of the transmission occurrs in the receivers
on time.
14  Using Arduino / Motors, Mechanics, and Power / Re: Need help making a charging circuit on: June 29, 2014, 06:19:52 pm
LIPO batteries dont like being deeply discharged.
Generally, the cell shouldnt be discharged below 2.8 V .
If the cell goes down to 0 V then it may not recharge at all, or will but will have lost much of its capacity.
You need some kind of cutoff to prevent this happening.
15  Using Arduino / Motors, Mechanics, and Power / Re: What will be the total power needed? on: June 28, 2014, 10:09:49 pm
The big power consumer will be transmitting the SMS messages, so a good start is to figure out how many of these per day
will have to be sent.
From there its fairly easy to work out the daily power consumption overall, which will set the battery size and the panel size.
Base the panel and battery size on the worst case scenerio, which is middle of winter and 1 weeks worth of cloud cover.
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