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This instructable will tell you how to operate Niftymitter 0.24, a small open source FM transmitter. More information on the design can be found at www.openthing.org/products/niftymitter.

This transmitter is in development and has not yet been approved by any regulators. It is a low power transmitter and works over a very short range - please ensure that by using it you are not interfering with any other nearby transmitters.

Step 1: Plug in a Source

Plug in any audio source into the 3.5mm jack socket. Set the volume on your source as low as possible.

Step 2: Switch On

Switch the transmitter on.

Step 3: Tune In

Make sure your transmitter and radio receiver are at least 2m apart to avoid tuning in to a harmonic frequency. Switch on your radio and tune the radio in to the transmitter. This should be broadcasting on a frequency between 88 and 91 MHz FM, transmitting silence.

It is difficult to be accurate here as: a) the frequency can very depending on atmospheric conditions and b) the scale on your radio might be calibrated differently to the scale on my radio, so would give a different reading of what frequency it is receiving on.

If you are having difficulty tuning in, you may need to retune the transmitter, which is described in step 5.
 

Step 4: Turn It Up!

Carefully turn up the volume on your audio source to a comfortable level. If you turn up too loud, the signal will sound distorted (it really doesn't need to to be very loud).

Step 5: To Retune Niftymitter

Slide out the circuit box.

Use a small 3mm slot headed screwdriver to adjust the 'trimcap'. It is best to use a screw driver with an insulated handle to minimise interference with the transmitting frequency, or ideally a trimtool such as this one from Rapid.
The trimcap is a small brass coloured component accessed by the hole marked 'tuning'. Clockwise for up, andticlockwise for down, it only requires very fine adjustment.
 

Step 6: To Replace the Battery

Slide out the battery tray. Unclip the battery from the PP3 clip, recycle/recharge and replace.

does this transmit in stereo or mono? thanks!
This transmits in mono. The current version mixes a stereo pair into a mono broadcast.
Hmm, is there anything out there that transmits in stereo? I was looking at this: http://makeprojects.com/Project/Micro-FM-Transmitter/721/1 <br> <br>but that doesn't say whether it's in mono or stereo, so I'm guessing it's stereo? <br> <br>otherwise it's just what I was looking for. :( <br> <br>thanks
Don't worry, I'm working on it!<br />
&nbsp;its&nbsp;February&nbsp;&nbsp;6, and we are still waiting for the proper instructable on how to build this. This is interesting but lack intructions&nbsp;
The project website is at www.openthing.org with links to the source files, and there are two instructables up explaining the assembly:<br /> https://www.instructables.com/id/Assembling-a-Niftymitter-v024/<br /> https://www.instructables.com/id/Assembling-a-Niftymitter-board-a-short-range-FM-/<br /> These were posted in December, sorry if you missed them.<br /> <br />
I&nbsp;agree with lemonie, please post an instructable on how to build this. <br /> Thanks
Could you not show us how to assemble it as well?<br /> <br /> L<br />

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Bio: I am a freelance design engineer and drummer. My business site is at http://www.zero-waste.co.uk and is often concerned with appropriate technologies ... More »
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