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Power supply for FM transmitter


FarrOut
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I bought one of the small transmitters on ebay.

It did not come with a power supply.

I tried to use a wall mount 'wart' but the 60 Hz hum was just too much.

I now use a battery supply.  I want a 110v supply so it can be remotely

shut off with an X10 module.

What are others using for clean 12v power?

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I bought one of the small transmitters on ebay.

It did not come with a power supply.

I tried to use a wall mount 'wart' but the 60 Hz hum was just too much.

I now use a battery supply.  I want a 110v supply so it can be remotely

shut off with an X10 module.

What are others using for clean 12v power?

You may want to try this on your power supply, about 6" back from the power input jack add a ferrite coil over the electrical wires, add another one about 2 feet further back from that one.   Also on your audio cable{s}, if they don't have ferrite coils, add one to each end of the audio cable{s} about 2 inches behind each plug on the audio cable.

 

This may cut out that 60hz hum you're picking up, which is probably being picked up by the audio cables.

 

My FM transmitters power supply has ferrite coils on it, as does my audio cable going from my computer to the FM transmitters audio in jack.

 

So you may want to try that, and depending on your Wal-Warts output, mine is 12VDC {as my trasnmitter works off 12VDC} and also has a 2 amp rating, you may need to get a different wal-wart, but if you do, still add the ferrite coils to the adapter.

 

This will hopefully resolve your hum issue, and hopefully with your current adapter.  an old laptop power supply works well for this purpose too..

 

In case you have no idea what a ferrite coil is, here's a link to MPJA and the ferrite coils I use:

http://www.mpja.com/040in-ID-Ferrite-Clamshell-EMI-Filter/productinfo/17842%20FL

 

Cost is $2.49¢ each.

 

Smaller size here:

http://www.mpja.com/037in-ID-Ferrite-Clamshell-EMI-Filter/productinfo/18463%20FL

 

Cost: $1.95¢ each

 

And here's one for only .99¢

http://www.mpja.com/025in-ID-Ferrite-Clamshell-EMI-Filter/productinfo/18466%20FL/

 

What I have found is the longer ones give better protection from the EMI that the power cord generates and the audio cables pick up.

 

 

Depending on the size of your adapters and audio wires, you may be able to get away with a cheaper, smaller one, just do a search for "ferrite" without the quotes on the MPJA website to see what the various types of ferrite cuils{EMI filters they offer}.

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can you just get a cord from Radio Shack? i bought one off of someone and one of the plugs was just sitting in the casing but isnt connected and just slides in and out.. hard to get our show started without music :(

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Your wall wart could also experience poor filtering which could cause AC hum should the suggested filtering described above doesn't  solve your problem.  Radio Shack and Parts Express stock 12vdc wall wart supplies should you need to replace it. 

 

Jim

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can you just get a cord from Radio Shack? i bought one off of someone and one of the plugs was just sitting in the casing but isnt connected and just slides in and out.. hard to get our show started without music :(

You can buy audio cords from Radio Shack, just make sure they have the ferrite coils on them, if they don't have that type, most computer stores do stock them.  Radio Shack may also sell the ferrite cols, but they'll probably cost double or triple what you can get them for at the MPJA website.

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The transmitter cost $45 on ebay, Shipped direct from China and did not come with a power supply.

The 'hum' is caused by the cheap, unfiltered power supply I found in a junk box.  

It goes away when I connect to a battery.

Thanks for the tips.  I'll find a PS that will work.

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Get a regulated 12v power supply, and make sure (if possible) to have the FM transmitter and LOR show computer on the same electrical outlet

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I've found a power supply that I hope will work.  I'll find out Friday night.

The power supply will be connected to an X10 module so that the transmitter shuts

down when the show is not running.

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