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16  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.
17  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?

18  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.
19  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.
20  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.

21  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.
22  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.
23  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.
24  Using Arduino / Networking, Protocols, and Devices / Re: 315mhz RF to turn on buzzer on: June 28, 2014, 02:46:39 am
Can you explain more in detail what you want.
How is the location of the cat related to the buzzer, or is the buzzer somehow going to be attached to the cat?
25  Using Arduino / Networking, Protocols, and Devices / Re: RF 434Mhz receiver doesn't detect remote on: June 27, 2014, 03:45:47 am
For hacking unknown types of remotes, you really need a scope of some sort, and you need to pull apart the transmitter
to gain access to the data pin of the 433 Mhz transmitting module in the transmitter.
By looking at the data pattern, its sometimes possible to work out the data format, but its usually a time consuming process.
26  Topics / Home Automation and Networked Objects / Re: Arduino Micro & RF Receiver problems on: June 26, 2014, 07:23:38 pm
From the Vellaman Web Site it says
The Transmitter is claimed to be compatable with the following devices.


You will need one of those to correctly decode the transmitters signal, or you will need to hack
the code format the transmitter uses, if you want the Arduino to be able to decode it.
It sounds like the transmitting module is using some kind of proprietary data format.
27  Using Arduino / Networking, Protocols, and Devices / Re: RF 434Mhz receiver doesn't detect remote on: June 26, 2014, 07:10:46 pm
The RC Switch library relies on the transmitting end and the receiving end using a SC2262 / SC2272 data format.
Most remote controlled power points and lights have these chips in them.
If the device you are using doesnt use this data format then the RC Switch library wont work.
28  Using Arduino / Sensors / Re: Improving ADC resolution with Instrumentation Amplifier on: June 24, 2014, 09:08:45 pm
There are opamps which are designed specifically for applications like this.
Have a look at
Its a selectable gain single ended opamp with gain blocks of 10 or 100 , and supports common mode voltages up to 50V
with a 5V supply .
29  Using Arduino / Project Guidance / Re: Capture raw RF 433Mhz signals without sound card on: June 23, 2014, 06:30:24 pm
Its quite common for garage door openers to use 433.92 Mhz , but most of the openers are rolling code transmitters
which means that you cant easily learn the code, as it changes everytime you push the button on the opener.
Making a universal 433 Mhz receiver is pretty impossible as theres no standard as to how the manufacturers of the transmitters  have to encode the data so no way to figure out where the data stream starts and stops.
30  Using Arduino / General Electronics / Re: 433 MHz garage door opener --> hackable? on: June 23, 2014, 07:55:52 am
Many garage door openers use a rolling code transmitter to provide extra security.
if yours does, they arnt hackable.
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