I want to make FM transmitter and receiver to be free from wires. I want to use it for listening audio from laptop, cellphone or Electric Guitar. I need good audio quality mono FM transmitter with transistors. Stereo transmitter is also considered to be made after mono, so all circuits are welcome.
There are already products such as this on the market.
I suggest that it would be far easier/cheaper to purchase an approved product that will comply with your local radio regulatory laws, rather than to design/manufacture one of you own, and then get it certified (which I know you won't do, because that would cost you 10s of thousands of £/$/€ to do).
It's for in-house use, not for broadcasting. Mono transmitter for my guitar and stereo is for music listening like wireless headphone. I want to build tiny transmitter and radio couples with tiny antenna. 10m range is enough.
If its wireless, it is broadcasting!
oljik:
It's for in-house use, not for broadcasting. Mono transmitter for my guitar and stereo is for music listening like wireless headphone. I want to build tiny transmitter and radio couples with tiny antenna. 10m range is enough.
That is like saying "I smoked pot, but didn't inhale"
Are you all high? Open the dictionary. It writes " distribution of content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum". That is like you saying "you are smoking that pot" when my neighbor was smoking in his house. It even does not say wireless, but typically one using it. So, do not write shit if don't know what I asked. What I asked was analog RF transmitter-receiver couple circuit. Mono and stereo couples with 10m radius, but increasing to 100m by adding antenna would be good. I think I have a good stereo FM transmitter circuit but I save it for later because it needs ordering some of it's parts abroad. It has to be zero latency, which is generally true for FM transmitters, and audio quality must not suffer. Do not mess with this thread if you don't have what I asked!!
oljik:
Do not mess with this thread if you don't have what I asked!!
What you are asking for is most likely to be illegal.
What I asked was analog RF transmitter-receiver couple circuit. Mono and stereo couples with 10m radius, but increasing to 100m by adding antenna would be good.
OK you have three options.
-
Do it illegally - this is not a project for a beginner RF engineering is a specialist skill that requires a lot of knowledge and test equipment.
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Do it legally - all of 1 above plus you have to get what you produce tested to ensure it complies with your local regulations which will cost in excess of $10,000.
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Buy one that has been through all these hoops.
Hi,
This forum is for Arduino controllers and associated circuitry.
Not for RF, non Arduino related items.
Google what you are looking for and see what it replies with.
It sounds to me you are looking for a wireless foldback system... google it!!!!!!
I have not offended you, I have supplied you with some information, information that you are looking for.
Hope it helps.... Thats all we are trying to do... Tom.. 
In most countries, it is legal to transmit on the same band as the regular FM radio stations, so long as you are under some specific power level, which I forget. It's like 0.5W? You can receive the transmission on any regular FM radio receiver, like headphones with a built in radio. Range will be very short - maybe less than 100 metres.
I'm sure the cheap $5 units on eBay haven't gone through any regulatory testing in the countries that they are sent to. But if they are under that limit, then they don't have to be tested or certified.
If you really want to learn a lot about RF design and you have thousands of dollars to buy the right test equipment, then you don't need an Arduino.
Interesting that a dictionary says broadcasting is to an audience; wikipedia goes one further and says "intended" audience.
Technically though, surely broadcasting is anything that is, well, cast broadly rather than narrowly. So what OP wants to do is broadcasting in spite of what his dictionary might say about audiences. Wireless in the air goes everywhere, as distinct to using wires where you can control where it goes.
oljik:
What I asked was analog RF transmitter-receiver couple circuit.
I'm not even sure what that means: how would you "couple" a Txer and Rxer?
In certain prescribed bands and with power output levels, in North America it is perfectly legal to built experimental transmitters. But the builder in the U.S.A. should be thoroughly familiar with Part 15 of the FCC regulations. https://transition.fcc.gov/Bureaus/Engineering_Technology/Documents/bulletins/oet63/oet63rev.pdf. Read page 3,
Hobbyists, inventors and other parties that design and build Part 15 transmitters with
no intention of ever marketing them may construct and operate up to five such
transmitters for their own personal use without having to obtain FCC equipment
authorization. If possible, these transmitters should be tested for compliance with the
Commission's rules.
MorganS:
In most countries, it is legal to transmit on the same band as the regular FM radio stations, so long as you are under some specific power level, which I forget. It's like 0.5W?
It is definitely not going to be 0.5W, that would give you a range of several miles/kilometres.
From the information given by aarg, it is going to be a few μW.
There used to be a really neat two transistor FM transmitter in the early 1970s, from a Danish company called Josty, on a 5x5cm board, with the inductor etched on the board. I've still got one, somewhere.
I think Velleman later did a version of it.
Nice quality audio. I'm sure there must be copies of the circuit on the Web.
I want to make FM transmitter and receiver to be free from wires. I want to use it for listening audio from laptop, cellphone or Electric Guitar. I need good audio quality mono FM transmitter with transistors. Stereo transmitter is also considered to be made after mono, so all circuits are welcome.
I would think Bluetooth would qualify .
What is the at the receiving end , a speaker or headphones ?
Do not mess with this thread if you don't have what I asked!!
That's pretty harsh , if not rude , coming from someone asking for free help. We are under no obligation to help you and comments like that will not make you very popular on the forum. A little humility would go a long way. I'm not the most tactful member on the forum but I don't even talk like that.
MorganS:
In most countries, it is legal to transmit on the same band as the regular FM radio stations, so long as you are under some specific power level
This is not in fact true. It might be true in the U.S. but it is not true in the vast majority of countries. The E.U. especially has no such provisions.
The thing is that most governments are a bit paranoid about allowing the normal citizen to build a transmitter mainly for security reasons and also to keep the bands free from unintended interference. The thing is that if you have to ask how to build a transmitter then you can't do it properly.
Attached are the FCC regulations for the U.S. only.
oljik:
Are you all high? Open the dictionary. It writes " distribution of content to a dispersed audience via any electronic mass communications medium, but typically one using the electromagnetic spectrum". That is like you saying "you are smoking that pot" when my neighbor was smoking in his house. It even does not say wireless, but typically one using it. So, do not write shit if don't know what I asked. What I asked was analog RF transmitter-receiver couple circuit. Mono and stereo couples with 10m radius, but increasing to 100m by adding antenna would be good. I think I have a good stereo FM transmitter circuit but I save it for later because it needs ordering some of it's parts abroad. It has to be zero latency, which is generally true for FM transmitters, and audio quality must not suffer. Do not mess with this thread if you don't have what I asked!!
Its only 10 M
Have you considered usin a modulated IR LED for this ?
oljik:
It's for in-house use, not for broadcasting. enough.
Yes it is in most jurisdictions. (Legal technicality)
Range is immaterial.
EDIT
Even RFID tags which have a range of a few cm have to be approved devices.
Grumpy_Mike:
This is not in fact true. It might be true in the U.S. but it is not true in the vast majority of countries. The E.U. especially has no such provisions.
This is also not true. You can legally buy and use FM transmitters in the EU to connect your smartphone to your car stereo.
Wikipedia
You can legally buy and use FM transmitters in the EU to connect your smartphone to your car stereo.
Sure you can, BUT the transmitter has to be type approved and you are not permitted to make it yourself.