user4081: I have come across the various blogs which talks about cloning RF remote using cheap 434 MHz Tx/Rx and RCSwitch library. 
I tried using RF 434 MHz ASK (https://www.sparkfun.com/products/10532) module with arduino, but the range I get it very less , just around 5-6 centimeters. Seems these RF 434 MHz modules are not stable. So I am planning to use now another RF Module which uses NRF905.
Link - 
http://www.ebay.com/itm/2pcs-NRF905-wireless-module-PTR8000-wireless-transmission-433-486-915MHz-/270963407796
My query is can I use NFR905 based RF modules which is also 434 Mhz to clone any existing remote working on 434 MHz. Please help

user2881: You can connect an external antenna to pin 8 on that module. Just use a piece of wire that is 17.3cm long. But since the range is that bad to start with, probably means it isn't tuned very well. I'd return it, or try fiddling with the pot at the back. Not sure why Sparkfun has these crap transceivers for sale. Transceivers without a crystal are very inaccurate in their frequency. 
If you only need to transmit, I'd suggest this products: https://www.sparkfun.com/products/10534
 . Those worked great for me, and are currently switching on the power sockets for my lights when it gets dark enough.

user630: 
can I use NFR905 based RF modules which is also 434 Mhz to clone any
  existing remote working on 434 MHz.

The answer is, inevitably, no, you cannot. Each such remote controlled device might have a different digital modulation scheme. Best if you could focus on one specific product and adjust your design to fit it.
Note that the two products you are referring to are both 433Mhz but differ by many other parameters, such as:

Supply voltage (5v vs 1.9v-3.6v)
Interface (single digital output vs SPI)
Capabilities (receiver vs  transceiver), 
Presence of a crystal
Power consumption 
Price 

This might affect your final design as well, and should be taken into consideration.
For example, from my experience, if you will shrink your project into a ATtiny85 at some stage, you might not have enough I/O pins to satisfy the NRF905, but enough for the Sparkfun's product (or a similar one).

but the range I get it very less , just around 5-6 centimeters.

The maximum range I got with the Sparkfun's module using a half-wave antenna (34cm) was ~40 meters inside a building and about 80 meters in open air. My testings with quarter-wave length was about ~30 meters inside a building. 

4081: <p>I have come across the various blogs which talks about cloning RF remote using cheap 434 MHz Tx/Rx and RCSwitch library. </p>

<p>I tried using RF 434 MHz ASK (<a href="https://www.sparkfun.com/products/10532" rel="nofollow">https://www.sparkfun.com/products/10532</a>) module with arduino, but the range I get it very less , just around 5-6 centimeters. Seems these RF 434 MHz modules are not stable. So I am planning to use now another RF Module which uses NRF905.
Link - 
<a href="http://www.ebay.com/itm/2pcs-NRF905-wireless-module-PTR8000-wireless-transmission-433-486-915MHz-/270963407796" rel="nofollow">http://www.ebay.com/itm/2pcs-NRF905-wireless-module-PTR8000-wireless-transmission-433-486-915MHz-/270963407796</a></p>

<p>My query is can I use NFR905 based RF modules which is also 434 Mhz to clone any existing remote working on 434 MHz. Please help</p>
 2881: <p>You can connect an external antenna to pin 8 on that module. Just use a piece of wire that is 17.3cm long. But since the range is that bad to start with, probably means it isn't tuned very well. I'd return it, or try fiddling with the pot at the back. Not sure why Sparkfun has these crap transceivers for sale. Transceivers without a crystal are very inaccurate in their frequency. </p>

<p>If you only need to transmit, I'd suggest this products: <a href="https://www.sparkfun.com/products/10534" rel="nofollow">https://www.sparkfun.com/products/10534</a>
 . Those worked great for me, and are currently switching on the power sockets for my lights when it gets dark enough.</p>
 630: <blockquote>
  <p>can I use NFR905 based RF modules which is also 434 Mhz to clone any
  existing remote working on 434 MHz.</p>
</blockquote>

<p>The answer is, inevitably, no, you cannot. Each such remote controlled device might have a different digital modulation scheme. Best if you could focus on one specific product and adjust your design to fit it.</p>

<p>Note that the two products you are referring to are both 433Mhz but <strong>differ by many other parameters</strong>, such as:</p>

<ul>
<li>Supply voltage (5v vs 1.9v-3.6v)</li>
<li>Interface (single digital output vs SPI)</li>
<li>Capabilities (receiver vs  transceiver), </li>
<li>Presence of a crystal</li>
<li>Power consumption </li>
<li>Price </li>
</ul>

<p>This might affect your final design as well, and should be taken into consideration.</p>

<p>For example, from my experience, if you will shrink your project into a ATtiny85 at some stage, you might not have enough I/O pins to satisfy the NRF905, but enough for the Sparkfun's product (or a similar one).</p>

<blockquote>
  <p>but the range I get it very less , just around 5-6 centimeters.</p>
</blockquote>

<p>The maximum range I got with the Sparkfun's module using a half-wave antenna (34cm) was ~40 <strong>meters</strong> inside a building and about 80 meters in open air. My testings with quarter-wave length was about ~30 meters inside a building. </p>
