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Wireless FM microphone real time voice/play transmitter

Hello
I am looking to buy/build a small FM wireless transmitter with built in microphone (similar to karaoke but not exactly ) to transfer voice or sound  from playing  musical instrument  to earphone.
It is meant only for practice purpose so does not need  high power, the distance between the microphone (the transmitter ) to earphone  is like from mouth to ear a few centimeters say about  50 cm.
I am electronic junior engineer and have knowledge and experience in electronics mechanics and wave buy. Before trying to develop a new product  I was looking for a readymade shelf product.
The first way I have searched the internet and reached manufacturer of Bluetooth solutions because of the plenty of Bluetooth earphone that are on the market, but quit a short time after I got some answers from the the Techs engineers  of the manufacturers that Bluetooth will not be my solution because It was not originally designed for true real time transmitting. The main problem is the latency time because there is a delay between the voice or play start until I hear it in the earphone there is improved in Bluetooth 4.1 and 4.2 that is 38 MS and may be not enough while fast playing,
So as I was advised I started looking in the RF FM area.
FM transmitters are long time in the market of stages and performers, there are high power grate quality transmitters that cost hundreds of dollars.

Here is the summary of what I need : 
     
I will need the smallest device (PCB) can be like FM spy bug transmitter.
built in microphone (on the PCB ) , built in battery compartment (on the PCB ),built in antenna a copper loop on the PCB (no wire)
Since there may be some problems like saturation of microphone or other problems with band width or  sound and sensitivity, sensitivity and control for the Microphone is important.
Easy calibration of  tuning and stability , may be digital tuning is better.
One option is to use the standard of radio FM 88-108 , but it possible that I can use FM VHF or UHF system that have both transmitter and receiver .
If there are no ready made products thatn I can easy build a kit , or from schematic diagrams
I will be thank full if you have any ideas.
Nevat Ben Haim Recomp Computers

Nevat (author) 1 month ago

Hello

Thank you so much for your advise , the solution you advised me is a good direction.
to be more specific in my project :

As i wrote the instrument i play is trumpet and there are in the market wired or wireless microphones for trumpet intended to be used for performance, usually they amplify the signal to a mixer and then power amplifier, i need to use it for different application which the signal sent in to an earphone (or on ears radio device) more like a "wireless monitor" .
I have already done some tests before i wrote to you with Bluetooth, with an cheap tv fm wireless transmitter and a radio fm transmitter , all had some problems of delay, instability poor sound, saturation and more .
I will try what you suggested and i will probably have some problems that may rise,that i will have to solve after .:
1. the volume of the nature trumpet is very loud so there may be saturation and distortion of the microphone signal.
2. the trumpet sound will be louder that the signal in the earphone so i will have to mute the trumpet some how .

Thanks again Nevat.

I guess then there is only investing in a proper and expensive commercial solution.
The specs you require are next to impossible to keep up on a hobby level.

Don't get me wrong but for under 1m I would go basic and use a simple wired solution.
There are plenty of FM microphones to choose from (for example Ebay) starting from kids toys and going all the way to high end microphones for stage use.
What you ask for is so specific that I can only assume there must be products for the purpose out there.
And if said products are too expensive then they are for a reason ;)

Take a mic system for and electric guitar - costs only a few bucks.
Add a FM audio transmitter to the output and use a small FM radio to listen to it.
Everything else will either involve creating quite complex electronics or spending a lot of money.

Nevat (author)  Downunder35m1 month ago
Hello
Thank you so much for your advise , the solution you advised me is a good direction.
to be more specific in my project :

As i wrote the instrument i play is trumpet and there are in the market wired or wireless microphones for trumpet intended to be used for performance, usually they amplify the signal to a mixer and then power amplifier, i need to use it for different application which the signal sent in to an earphone (or on ears radio device) more like a "wireless monitor" .
I have already done some tests before i wrote to you with Bluetooth, with an cheap tv fm wireless transmitter and a radio fm transmitter , all had some problems of delay, instability poor sound, saturation and more .
I will try what you suggested and i will probably have some problems that may rise,that i will have to solve after .:
1. the volume of the nature trumpet is very loud so there may be saturation and distortion of the microphone signal.
2. the trumpet sound will be louder that the signal in the earphone so i will have to mute the trumpet some how .

Thanks again Nevat.