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Description: These wireless transmitters work with our 315MHz receivers. They can easily fit into a breadboard and work well with microcontrollers to create a very simple wireless data link. Since these are only transmitters, they will only work communicating data one-way, you would need two pairs (of different frequencies) to act as a transmitter/receiver pair.

Note: These modules are indiscriminate and will receive a fair amount of noise.  Both the transmitter and receiver work at common frequencies and don't have IDs. Therefore, a method of filtering this noise and pairing transmitter and receiver will be necessary. The example code below shows such an example for basic operation. Please refer to the example code and links below for ways to accomplish a robust wireless data link.

Features:

  • 315MHz
  • 500ft range (given perfect conditions)
  • 4800bps data rate
  • 5V supply voltage

Documents:

Comments 32 comments

  • Be careful using the 315 Mhz transmitter near a GPS receiver, The fifth harmonic of 315 MHz is 1575 MHz. 1575 MHz is the GPS carrier frequency. Depending upon your GPS receiver, you can get GPS receiver desensitization or total jamming of the GPS signal.
    For GPS applications, the 434 MHz link is a better choice. For bi-directional links have the GPS send on 434 Mhz and receive on 315 MHz. This get the potentially interfering 315 MHz signal further from the GPS.

  • Could I send a one-bit (on/off) signal without encoding, virtualWire? Basically, without a uC. I just want an LED to turn on connected to the receiver when a button is pressed on the transmitter. Is this possible?

  • These transmitters are awesome! I am using one to control off the shelf wireless outlet switches that are available for dirt cheap during the holiday season. I used the corresponding 315MHz receiver and my Rigol DS1052E scope to decode the protocol from the remotes and reimplemented it on an ATTiny2313 microcontroller. I’m using a capacitor charge pump driven by a microcontroller PWM pin to boost the 5V USB voltage powering my board to 8-9V DC for the transmitter. It can take up to 12V and the higher voltage means longer range. This setup easily covers my whole house even though the transmitter is located in the front corner room. I can control 12 outlets (lamps, fans, Christmas lights, whatever) from anywhere using my phone. Thanks 315MHz transmitter, you’re awesome! The total board (USB serial, ATTiny2313, transmitter, homemade PCB, etc) cost around $10 total and the outlets are $15 for 3.

    • I was about to do exactly the same thing. Don’t suppose you can share what you found out about the protocol to save me the trouble of working it out too? Thanks.

  • Is there a difference between the 315MHz and 434MHz versions of this? (Not in the physical product, but in the range, quality, etc.)

  • I would like to see the example circuit you were able to get the 500ft range. I am interested in knowing the antenna configuration + groundplane. Were you able to use something like ANT-315-HETH from Linx technologies?

    Also - Supply Voltage - I have seen some of these have a range between 3-12v. Is the 5v the maximum? The data sheet says 1.5 ~12V. Do you have estimates of range based on voltage. Trying to go 100m.

  • http://www.youtube.com/watch?v=wlpXzF0Gv4U&list=PLADOxch6A_u-stWlF93snAUoYDmZ5_6Tg&index=1

    Wireless communication between a PC and quadcopter using this RF transmitter, receiver…

  • I used this and the accompanying receiver in an (Arduino) tutorial. Link. I also used your code in the tutorial, hope you don’t mind. (Code was accredited to Sparkfun, the header was left at the top)

  • The Features here list 5V supply voltage but the datasheet supply voltage 1.5-12 and an operating voltage of 3-12.

    So can this be used with 3.3V circuitry?

  • If I used this transmitter as a simple on/off sort of beeper, could I get more than 500 feet of range? I want to use it as an RF beacon, and put it on a remote control plane so I can home in on the signal with the receiver that goes with this. Also I can’t send audio tones over this, right?

  • I wonder if you could put a transistor on the antena line to get more power or paralell 2 of them to get double the output power…

  • I am using one of these and companion receiver with RC chips TX-2B, RX-2B for simple on premise remote control: they work great. No issues with decoding errors. I power up the transmitter only when new data is ready to reduce potential interference. Using well bypassed power supply lines (10uF tantalum in parallel with two .1 uF). Looking forward to my next application.

  • How does this work? You apply power and then it transmits a signal?

  • Is the Arduino Library and Example Code outdated for this? When trying it all I get is a bunch of compile errors (using Arduino IDE 1.0.1) for VirtualWire.h and then it saying one of the vw_ functions isn’t declared. Kind of annoying to have libraries and example code that doesn’t work :(

    In answer to my own question yep, Sparkfun needs to update their Library links.

    v1.9 works here: http://www.open.com.au/mikem/arduino/

  • http://mbed.org/users/4180_1/notebook/ir-and-rf-remote-controls/ has a code example for mbed sending characters to the matching receiver

  • Anyone know the best antenna shape for best range?

    I’m trying to rig up a detector to tell when the mailman has dropped off the mail, but so far the receiver starts failing just ~5' from the mailbox.

    So far I have a 5/8 wavelength antenna, completely coiled. The whole thing is powered on 12V, which is the rated maximum of the transmitter.

    Is straight better than coiled?

    • Im not sure, maybe put a wire along the post?(or coil it around the post.) I might get one, seeing as they’re online 3.50

  • You get what you pay for holds true for this little gem. Thinking that an xbee would be overkill to transmit a 4 byte message, I decided to try this product. I purchased one of each flavor. Both 315 and 433 Mhz radios produce nothing more than a continous stream of noise that no amount of software, checksums and programming can reliably filter out. I am lucky to get 1 good 4 byte message out of 20 transmits.

    • I have to admit, I damn nearly pulled out my hair using these 315 MHz TX and RX modules. BUT I finally got them to work and consistently at 2400Bps. The trick to make them work for me was to add filtering caps (330uF or larger) to the power lines feeding the modules. The second thing is the antennas, during testing at close range (5-12 inches), the antenna on the RX had to be removed, I don’t know why, but if I didn’t it caused nothing but a constant stream of garbage. The antennas also needed to be ~9 inches in length and straight. After this, I can transmit the string ‘|T:264|H:500|C:764;’ (Temp 26.4C, Humidity 50% and checksum temp+humid read from DHT22) every 10 seconds with little failure attempts.

      • Reading this and other comments, I have the following suggestions. 1) have clean, stable power going to the Tx and Rx units. These have gain and mixer stages that will pick up and amplify pretty much everything. Put a scope on the rails and make sure they are steady when the Tx/Rx units are operating. 2) Put a low-pass filter on the Tx output. It doesn’t have to be really steep and can have a passband >= 330 MHz. That will make sure that the harmonics mentioned above don’t interfere with other devices. Of course, a bandpass filter would be better, and is only slightly more complicated. If someone can determine the output impedance of the Tx antenna port, then try to match that. 3) The wavelength of a 315 MHz transmitter is about 95 cm. You should get decent efficiency with a ¼ wavelength = 23.8 cm wire antenna provided it’s isolated from other conductors. Check out ARRL info on antennas for other kinds that may be useful… 4) If you are lucky enough to have a spectrum analyzer, use it to see what’s going on with the Tx. Pay attention to “spurs” outside the desired band and the above-mentioned harmonics. If you only have an oscilloscope, you may still be in luck if it’s digital storage and has an FFT mode. You can single-shot trigger and take a look at the spectrum using the FFT (of course, the scope has to be 350 MHz or better (probably 500 MHz)…

        Have fun,

      • I will try the filtering caps, and report back how it worked for me. I’m hoping this will make it work better!

  • I’m having trouble with this product. I have two arduinos one transmitting and one receiving and I’m confident they are wired correctly. None of the hello worlds are working. I can plug a wire from the antenna of the sender to the antenna of the receiver and the data goes through, but wirelessly is still a mystery. Is there a simple way to diagnose if I have a bad transmitter or receiver?

  • other TWS-BS modules? Sparkfun sells the 3 (433.92) and this one, the 6. I’m looking for a TWS-BS-5 (318) and I am unable to find a source. Anyone here got some ideas?

  • As an example of what you can do with these, we created a TPMS/key fob spoofer with the older version of this and an FTDI chip. Significantly cheaper than the USRP some people were using, but the signal was much noisier.

  • How much does it weigh?

  • So, is this just an improved version of WRL-08945?
    It seems to have about the same specs (315MHz, 500ft, 4800bps) at twice the price.
    Also, the spec sheet doesn’t indicate what to use for an antenna. I assume it would use a 23cm wire like the WRL-08945 modules do.

    • I did the math and came up with 17.8in for a straight wire antenna. I tried it and it seemed to make a big diference at 2400 baud.

    • a length of wire is fine.
      it’s the same as the other. I lowered the price on 8945 since it’s an old supplier and we can’t get them anymore. they retailed for the same as these. snatch up the others cheap while we still have them.

      • Guaranteed the old batch of transmitters (WRL-08945) work fine with the new batch of receivers (WRL-10533)?

        • I bought a WRL-08945 transmitter and a WRL-10533 receiver, and I can tell you that they work together.
          Just make sure to use an external antenna, unless you want to get a 2 centimeters range.


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