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FM Transmitter

Discussion in 'General Electronics Discussion' started by GreggSudduth, Aug 21, 2013.

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  1. GreggSudduth


    Aug 21, 2013
    Hello everyone,

    I would like to find someone that could build me a short range FM Transmitter with a voice recorder. I would like to plug it in to a 110 volt plug. The message would loop forever.

    I would like for it to have a simple record button that recorded the message with a built-in mic. I would like to have four (4) buttons that would switch to 4 different FM Channels. No need to scroll the entire available range of allowable FM channels.

    I would need the electrical diagram that I could send to a company to reproduce the product.

    I want it to be simple and small. I would like the electric outlet part of be simple also, no big DC converter or anything like that. Small and simple.

    Anyone think they know how to do this? Would love to hear from you and how much you would charge to make me a working demo unit with diagram.

    Thank you so much in advance for your help.


    [email protected]
  2. KrisBlueNZ

    KrisBlueNZ Sadly passed away in 2015

    Nov 28, 2011
    Have you tried asking on
  3. GreggSudduth


    Aug 21, 2013
    Yes I have posted on Freelancer. Thank you for that information. I also posted on hoping to get more feedback. Thank you very much
  4. Fish4Fun

    Fish4Fun So long, and Thanks for all the Fish!

    Aug 27, 2013

    If I might suggest...when requesting bids/proposals for technical devices/software/firmware you need to do your due-diligence. Examples follow:

    1) "Short-Range" is almost meaningless. It could mean a mW transmitter with a 1 meter range like an automotive MP3 player that connects to a car's FM radio, or it could mean a 300W transmitter with a 10 mile radius. Furthermore you have neglected to indicate if the device has to be compliant with any laws, codes, rules or standards.

    2) "electrical diagram"....I don't mean to pick, but electrical diagrams are for buildings, boats and cars, and depict wire routing; schematics are circuit diagrams that indicate component selection and connections. With RF circuits even schematics fail to convey important details, what you would truly want is a full PCB layout.

    3) "I want it to be simple and small"....again, you are failing to communicate anything meaningful. Both "Simple" and "Small" are qualitative/comparative descriptions that convey no useful information. A "small" ship might weigh 500 Tonnes, a "small" boat might weight 500 pounds, and a "small" model boat might weigh 500 grams. Simple is even more meaningless, you don't even qualify what it is that you want "simple"; ie: do you want: a "simple user interface", a "simple design" or perhaps a "simple proposal"? Regardless, w/o anything to compare it to, simple is still meaningless.

    4) "the electric outlet part of be simple also", so much going on here. First, an "outlet" in common parlance generally refers to a wall receptacle where one might connect a device that needs to be powered. "Outlets" are highly region specific and imply different electrical specifications; some are 120Vac/60hz, 220Vac'60hz, 220Vac/50hz being the most common voltages, beyond the outlet Voltage are specific current specifications. Even assuming you mean a "common US outlet" implying 120V/60hz, why would your FM transmitter have an outlet? Obviously you mean you want the device to be "line-powered"; and you seem to suggest that you want an internal power supply rather than a "wall-wart".

    5) Finally, you have omitted any indication of the device's purpose. While this is not always a "deal breaker", it does place a huge emphasis on tight design specifications. Think of it like this: if you specify you need a power supply that will accept 80Vac-270Vac 46hz-70hz with an output of 6Vdc-38Vdc @2A +/- 100mA continuous duty; or simply say: I want a line powered power supply to drive 2-12 LEDs @ 2A in both cases you have conveyed enough information to expect reasonable offers.

    Ok, enough of that, let's get to what I think your real question is:
    "Anyone think they know how to do this? Would love to hear from you and how much you would charge to make me a working demo unit with diagram."

    Hrmmm, since you have utterly failed to provide any technical specifications or even intended use this is going to be a real SWAG. Many State DOTs, cities and some Airports use "short range FM transmitters" to convey traffic/flight information to approaching motorist. I would guess that one of these systems costs between $10k and $250k and requires FCC licensing and regulation. To commission someone to design a similar system from the ground up could easily cost 10X as much. As a side note, since most of these traffic systems are being replaced by a more modern traffic alert network it might be possible to purchase used units for salvage prices. Of course you would need to do due-diligence to determine exactly what you were looking for. who purchased them and who might be trying to unload them as well as any FCC regulations that apply to them.

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