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1  Using Arduino / Project Guidance / Re: MPPT Solar controller - based on Tim Nolan's ideas on: Today at 02:46:42 am
You get roughly around 25 - 30% improvement in power input to the battery, at least that what I get from my
home made MPPT charger.
The cost / effort needed depends a lot on how much power is available from the Solar Panels and how big the batteries are.
Mosfets are very easy to blow up if you get something wrong , you have to be very careful.
Tim Nolans design is a good one to start with, but be very careful if you start changing the design.
Mppt charge controllers need a fair bit of design work to make sure you arnt stressing the Mosfets,as if you do
they will either blow up the instant you turn it on , or after an hour or so.

2  Using Arduino / General Electronics / Re: Usb to uart and 433MHZ on: July 30, 2014, 01:33:23 am
That will work OK.
Those 433 Mhz receivers produce a lot of noise on their data pins , so you will need some kind of protocol
in your PC to detect your transmitted data.
3  Using Arduino / General Electronics / Re: Usb to uart and 433MHZ on: July 29, 2014, 05:33:53 pm
What are you intending to use the modules for.?
They need some kind of signal processing like Virtualwire to work properly.
Usual way to use them is with an Arduino at both ends, and then you connect the receiving Arduino to your PC.
4  Using Arduino / Motors, Mechanics, and Power / Re: Lithium-ION-POLY Batteries.... etc. on: July 29, 2014, 12:24:30 am
I use them a lot.
Pretty useful and longer lasting than NIMH.
However, you must not overcharge them , or over discharge them .
ie no more than 4.2 V when charging and no less than 2.8 V when discharging.
The protected ones are more foolproof.
Also, be careful of the stated capacities, as there are a lot of fakes, especially if you are buying them on Ebay
or from Chinese sellers.
Anything over 3300 mah , unless its from Panasonic,Sony  or Sanyo, is likley to be a fake.

5  Using Arduino / General Electronics / Re: Wind generator for 12v battery - no controller? on: July 28, 2014, 02:38:43 am
You dont need a charge controller with a tiny Solar panel, as the battery will simply clamp the Solar panels output
to whatever the battery voltage is.
If the Solar panel can only make 250 ma , then as long as the battery is at least 2.5 ah or more , it will never be overcharged.
You only need charge controllers with large solar panels that can make 100s of watts, or if you have a tiny battery.
6  Using Arduino / General Electronics / Re: arduino-18650 charger-help. on: July 25, 2014, 06:42:22 pm
Charging LIPOs in series needs a balance charger, which ensures that neither of the cells is overcharged.
You could make one with an Arduino and a couple of fets , but Im not sure how this solves your problem.
7  Using Arduino / Sensors / Re: Measurement of DC current with non invasive method on: July 23, 2014, 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.
8  Using Arduino / General Electronics / Re: ADC false readings on: July 23, 2014, 02:40:21 am
Could be noise on the opamps output.
What gain does the opamp have , and what is it amplifying.
9  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.
10  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.
11  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.
12  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?
13  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.
14  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.
15  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?

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