RF Module

[dhouston]

I can buy it from an international vendor, but, the problem is the delivery charges are like two times the cost of the modules itself...

That's only true if you're trying to buy in very low quantities. I bought non-standard (i.e. the frequency is not one listed in their catalog and required different SAW resonators) 310MHz TWS-A type transmitters from Wen Shing in Taiwan for about $3 each in quantities of 100 pcs. Shipping charges were about $25 for air express to the USA. On the other hand, they wanted more than $5 each for the RWS-310 receivers (which are in their catalog) and I can buy an identical receiver (of better quality) made by another Taiwan firm from Mouser Electronics for $5 in single quantities.

There are several excellent application notes on the Linx Technologies website.

• http://www.linxtechnologies.com/inde...ection=support

RF Monolithics also used to have some good app notes but I haven't checked that lately.

• http://www.rfm.com

If you are looking for lower quantities I think you are still better off to buy the TWS-434A transmitter available from 20 or more vendors around the world. Even Velleman sells it.

If you haven't read it, the third page of the PDF I referenced earlier in the thread gives a schematic, with component values, for a SAW controlled 433.92MHz transmitter that uses pretty much the same circuit, merely replacing the LC frequency components with the SAW resonator.

[ra68gi]

Here in Bangalore, India, there is no one who sells RF modules...

Hi Shahid,
There are many vendors selling RF modules in India. Checkout these...
www.modielectronics.com (Chennai, Tamilnadu) or www.vegakitindia.com
I even found linxs tx,rx module capable of transmitting over long distances in Chennai.
www.rentron.com is another place with a lot of resource on rf modules.
Mr.Bruce who is a member of this form and also proprietor of Reynolds electronics (www.rentron.com) can help you on this subject.
Raghunathan.

[shahidali55]

Hello dhouston,
The file you posted (UR19A.PDF) has a nice transmitter schematic.
But, the complete details of L1 are not given.
Do you have a reciever schematic for this transmitter ???

[dhouston]

Hello dhouston,
The file you posted (UR19A.PDF) has a nice transmitter schematic.
But, the complete details of L1 are not given.

L1 is a circuit board trace that acts as the antenna. If you're going to build something, build the one in the http://jap.hu/electronic/rf/el9805.pdf link.

Do you have a reciever schematic for this transmitter ???

X-10's RR501 used almost exactly the same circuit as the Ming receiver for which you found a schematic. Or, you can do a Google search on "RR501 Orysh schematic".

The RF1 transmitter and receivers shown on the site cited by ra68gi http://www.modielectronics.com/RFPG_1.htm are the ones made by Wen Shing (or are clones thereof) that I mentioned earlier. You cannot go wrong with them.

OOOPS! The RF modules in both links from ra68gi are from HiMark (Taiwan). X-10 now uses similar HiMark modules in their latest interface (CM15A). As I recall, HiMark has schematics and parts lists on their website.

[shahidali55]

I finally found something on google that looks real easy to make.
Can someone tell me if these circuits will work and what range they might have?
http://www.cappels.org/dproj/LCRFLIN...tr/TRFxmtr.htm
http://www.cappels.org/dproj/LCRFLIN...rF/TRFrcvr.htm

[shahidali55]

Has anyone got any other ideas???
I just need a simple circuit that is capable of transmitting and recieving data.
Range - 25 to 30 metres...
Frequency - Anything . . .

[dhouston]

I just remembered this one.

• http://www.piclist.com/techref/io/rf/simpletx.htm

[Melanie]

Shahidali, as you seem to want to build one yourself instead of buying ready made devices, the final result and performance will very much depend on your build quality and the quality of components you use and the antenna you employ at both the transmitter and receiver and also the frequency you end up operating on. Since the inductor will be constructed by you, I emphasise build quality. So, why not try building some of the many circuits you now have acquired (including some you've found yourself), then come back and tell us how you've done and how well they have performed. However, without some good test equipment, or alternatively at least a tuneable receiver in the frequency band of your transmitter, you will have a hard time achieving a measure of success whilst working in the dark, as you won't even know what transmit frequency your construction has ended up with.