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 Posted: Mar 13, 2010 - 06:46 AM |
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Joined: Mar 06, 2010
Posts: 22
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Sir,
I have to make a project on RF Remote Control. I followed the following article http://www.thinklabs.in/resources/?p=12
In the circuit diagram shown, I noticed two volages, Vcc and Vdd. These are common voltages or separate voltages.
I have used in total four voltage sources, for Tx, encoder, with common ground and Rx, decoder, with common ground.
But still I m not able to make it work…
Please help. |
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Posted: Mar 13, 2010 - 07:06 AM |
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Joined: Mar 14, 2006
Posts: 472
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naveen24 wrote:
Sir,
I have to make a project on RF Remote Control. I followed the following article http://www.thinklabs.in/resources/?p=12
In the circuit diagram shown, I noticed two volages, Vcc and Vdd. These are common voltages or separate voltages.
I have used in total four voltage sources, for Tx, encoder, with common ground and Rx, decoder, with common ground.
But still I m not able to make it work…
Please help.
Hey naveen,
I am not being dismissive but it took me about 5 seconds to find the answer for your Vcc/Vdd question on the first diagram on the web page. In fact it is there twice.
Someguy |
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Posted: Mar 13, 2010 - 07:06 AM |
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Joined: Jul 02, 2005
Posts: 2537
Location: Melbourne, Australia
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Hello Naveen,
The Holtek encoder/decoder datasheets (you did look at them didn't you?) shows that they can operate with a positive supply of between 2.4 volts and 12 volts. This it calls VDD. VSS is its ground connection.
The ASK units only operate with 5 volts which it calls VCC.
The project diagram states "VDD=VCC=5V". So you need to connect +5 volts to the holtek device and the ASK unit of the transmitter section and a separate +5 volts to the holtek and Ask components of the receiver sections. The transmitter has its own ground connections which are NOT connected to the receiver section ... otherwise there would be no point in using a transmitter at all.
Hope that helps.
Cheers,
Ross |
_________________
Ross McKenzie
ValuSoft
Melbourne Australia
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Posted: Mar 13, 2010 - 07:14 AM |
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Joined: Mar 15, 2009
Posts: 13
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Posted: Mar 13, 2010 - 07:18 AM |
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Joined: Mar 06, 2010
Posts: 22
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Sir,
Thanks to all for your reply.
@ValuSoft Sir, yes I could make out that Tx and Rx ground are not same. I meant that ground for Tx and encoder are same and ground for Rx and decoder are same.
I would look into Vcc and Vdd concept.
Regards |
Last edited by naveen24 on Mar 13, 2010 - 07:25 AM; edited 1 time in total
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Posted: Mar 13, 2010 - 07:22 AM |
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Joined: Mar 06, 2010
Posts: 22
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Posted: Mar 14, 2010 - 06:33 AM |
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Joined: Mar 06, 2010
Posts: 22
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Sir,
Is there any way so that I can check my transmitter receiver module?
Regards |
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Posted: Mar 14, 2010 - 07:24 AM |
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Joined: Mar 06, 2010
Posts: 22
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Someguy22 wrote:
naveen24 wrote:
Sir,
I have to make a project on RF Remote Control. I followed the following article http://www.thinklabs.in/resources/?p=12
In the circuit diagram shown, I noticed two volages, Vcc and Vdd. These are common voltages or separate voltages.
I have used in total four voltage sources, for Tx, encoder, with common ground and Rx, decoder, with common ground.
But still I m not able to make it work…
Please help.
Hey naveen,
I am not being dismissive but it took me about 5 seconds to find the answer for your Vcc/Vdd question on the first diagram on the web page. In fact it is there twice.
Someguy
Sir,
Is there any way I can check my transmitter receiver module for the circuit diagram posted on link above?
Regards |
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Posted: Mar 14, 2010 - 10:53 AM |
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Joined: Jul 02, 2005
Posts: 2537
Location: Melbourne, Australia
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Do you have access to an oscilloscope?
If yes, first look at the data line into the transmitter. It should be a stream of 1s and 0s. Then do the same on the data line out of the receiver.
Cheers,
Ross |
_________________
Ross McKenzie
ValuSoft
Melbourne Australia
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Posted: Mar 14, 2010 - 12:17 PM |
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Joined: Mar 06, 2010
Posts: 22
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valusoft wrote:
Do you have access to an oscilloscope?
If yes, first look at the data line into the transmitter. It should be a stream of 1s and 0s. Then do the same on the data line out of the receiver.
Cheers,
Ross
Sir,
Regards. Actually, in the circuit, I provide data 1010 and I find voltage of 1.83V at Data Out. But the voltage at antenna terminal is 0Volts. Does this mean no data transmission taking place?
Ultimately, on Rx Data In I fint 0Volts.
Please help.
Regards |
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Posted: Mar 14, 2010 - 12:40 PM |
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Joined: Oct 07, 2002
Posts: 978
Location: Skørping Denmark
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| For 433MHz stuf I use a handheld scanner just to veryfy that the transmitter send something. |
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Posted: Mar 14, 2010 - 12:50 PM |
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Joined: Jul 02, 2005
Posts: 2537
Location: Melbourne, Australia
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You have attached suitable antennas for 433MHz?
And you cannot just attach a multimeter to the antenna .... does anyone else at your university have a functioning system? |
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Ross McKenzie
ValuSoft
Melbourne Australia
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Posted: Mar 14, 2010 - 12:59 PM |
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Joined: Mar 06, 2010
Posts: 22
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valusoft wrote:
You have attached suitable antennas for 433MHz?
And you cannot just attach a multimeter to the antenna .... does anyone else at your university have a functioning system?
Yes Sir,
I have two 72cm telescopic antennas.
And regarding help in University, Sir, I m not currently into studies. I m preparing for GRE. But yes I attended course on Embedded and doing this for quite some time. But didnt come across this project from any mate.
Regards. |
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Posted: Mar 15, 2010 - 01:30 AM |
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Joined: Jul 02, 2005
Posts: 2537
Location: Melbourne, Australia
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OK, lets start with your antennas.
The theoretical full wave length at 434 MHz is 300/434 = 69.1244 cms. The real world means that we must apply a velocity factor of around 0.93 to 0.98 to this calculation. This produces a full wave antenna length of between 64.4 and 67.74 cms. I would suggest that your 72 cm antennas are too long for correct matching. Also I think they are wrong because, in my experience, these ASK units expect to drive quarter wave antennas. In the past, I have used around 17 cm of plastic coated stiff (single core) hook up wire.
If you start with a slightly longer wire antenna, you can then cut a small amount off the tip until you get good performance.
Hope that helps.
Cheers,
Ross |
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Ross McKenzie
ValuSoft
Melbourne Australia
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Posted: Mar 15, 2010 - 02:19 PM |
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Joined: Mar 06, 2010
Posts: 22
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valusoft wrote:
OK, lets start with your antennas.
The theoretical full wave length at 434 MHz is 300/434 = 69.1244 cms. The real world means that we must apply a velocity factor of around 0.93 to 0.98 to this calculation. This produces a full wave antenna length of between 64.4 and 67.74 cms. I would suggest that your 72 cm antennas are too long for correct matching. Also I think they are wrong because, in my experience, these ASK units expect to drive quarter wave antennas. In the past, I have used around 17 cm of plastic coated stiff (single core) hook up wire.
If you start with a slightly longer wire antenna, you can then cut a small amount off the tip until you get good performance.
Hope that helps.
Cheers,
Ross
Sir,
Thanks for your guidance. I would surely try this out and would post the result.
Regards. |
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