FM transmitter

mrcheez

Spotted this FM transmitter (http://wholehousefmtransmitter.com/home-stereo-fm-transmitter/).

I'm looking to broadcast music throughout all my house's radios (through walls/floorboards) on 88-90 MHz which is RTE Radio 1's frequency (the station the radio is permanently set on).

When I disable it then the radios will go back to playing RTE radio 1.

Reckon this is what I'm looking for? Will it "take over" the RTE frequency when I activate it?

mrcheez

I also spotted this at $50.50

http://www.ebay.com/itm/7W-CZE-7C-Stereo-PLL-Car-MP3-FM-Transmitter-Radio-Broadcast-Station-76-108-MHz-/301029017316?hash=item4616ba46e4:g:zq4AAOSwPhdVCPVY

Would this offer the same functionality? It's not clear if it's purely for use in a car or not.

Greenman

Heading for the lock. :-)

mrcheez

Illegal I take it?

Losty Dublin

mrcheez wrote: »

Illegal I take it?

In general it's both illegal to own and illegal to operate transmitters without licences. There was talk of exempting some of the iPod type devices that are exempted in the UK by OFTEL; it hasn't happened here as of yet but if you were to do it then they are cheaper and far less hassle to work with.

More Music

Is there another house nearby/next door?

If so, they will also get to hear your musical ramblings when the urge takes you.....whether they want to or not.

It's just they might prefer Ronan Collins' selections.

Fuzzy Clam

Losty Dublin wrote: »

In general it's both illegal to own and illegal to operate transmitters without licences. There was talk of exempting some of the iPod type devices that are exempted in the UK by OFTEL; it hasn't happened here as of yet but if you were to do it then they are cheaper and far less hassle to work with.

It's Ofcom in the UK.
Low power devices (up to 50 nW, CE marked etc) are permitted here, licence exempt, and have been for a number or years.

L1011

Losty Dublin wrote: »

In general it's both illegal to own and illegal to operate transmitters without licences. There was talk of exempting some of the iPod type devices that are exempted in the UK by OFTEL; it hasn't happened here as of yet but if you were to do it then they are cheaper and far less hassle to work with.

We have allowed unlicensed microwatt (or nanowatt possibly) transmitters here for some years. Many non apple phones have them.

TallGlass

You might find that it might even be too low powered to overtake the FM signal from RTE.

https://www.aareff.com/en/1w-fm-transmitter.htm

1 Watt should do you from a good TX along with a 5/8 aerial outside the house. I still wouldn't recommend broadcasting on RTE FRQ but.

Fuzzy Clam

TallGlass wrote: »

You might find that it might even be too low powered to overtake the FM signal from RTE.

https://www.aareff.com/en/1w-fm-transmitter.htm

1 Watt should do you from a good TX along with a 5/8 aerial outside the house. I still wouldn't recommend broadcasting on RTE FRQ but.

(S)he only wants to transmit around the house, not the neighbourhood.

mrcheez

Fuzzy Clam wrote: »

(S)he only wants to transmit around the house, not the neighbourhood.

Pretty much. The range would probably need to be around 20m max, but work through brick walls.

Since posting I found there seem to be loads on ebay for around $50 incl delivery so I guess they'll all probably work.


Like this one: http://www.ebay.com/itm/Home-FM-TRANSMITTER-100mW-500mW-Power-adj-76-108Mh-/271642045167?ssPageName=ADME:X:AAQ:US:1123

Fuzzy Clam

mrcheez wrote: »

Pretty much. The range would probably need to be around 20m max, but work through brick walls.

Since posting I found there seem to be loads on ebay for around $50 incl delivery so I guess they'll all probably work.


Like this one: http://www.ebay.com/itm/Home-FM-TRANSMITTER-100mW-500mW-Power-adj-76-108Mh-/271642045167?ssPageName=ADME:X:AAQ:US:1123

Once you are aware that it is illegal.

4068ac1elhodqr

I have one that used to have in the car before it could manage mp3, legal and works fine from batteries or the cig lighter across 88-104.
Don't expect it (or anything similar i.e. consumer based products) to work well beyond 5 metres (at the most).
Bought new for 15e from well known high street tech store, don't use it much anymore.

mrcheez

Fuzzy Clam wrote: »

Once you are aware that it is illegal.

What sort of range would something like that have?

Fuzzy Clam

mrcheez wrote: »

What sort of range would something like that have?

If you use the small aerial that comes with it , it should cover the house.

TallGlass

Fuzzy Clam wrote: »

(S)he only wants to transmit around the house, not the neighbourhood.

In theory it would broadcast far but in practice I have found its the opposite and wouldn't go that far. 1 watt is not a lot of power, maybe use a different aerial with low or no gain so not to go that far.

The eBay micro transmitters will work, but I wouldn't expect audio to be great. I was under the impression that up to 1watt was legal to broadcast.

coylemj

Can you not do it on a frequency that's unused in your area? That's what people with in-car FM transmitters typically do. Picking the RTE frequency is a bit selfish as in all probability you will interfere with your neighbour's reception.

mrcheez

coylemj wrote: »

Can you not do it on a frequency that's unused in your area? That's what people with in-car FM transmitters typically do. Picking the RTE frequency is a bit selfish as in all probability you will interfere with your neighbour's reception.

Only if the neighbour is within broadcast distance surely?

This is for a farm house, nearest neighbour is several hundred metres away.

end of the road

mrcheez wrote: »

Only if the neighbour is within broadcast distance surely?

This is for a farm house, nearest neighbour is several hundred metres away.

why do you want to block out the RTE signal anyway? surely simply not listening to it and broadcasting on a clear frequency would be the best option

mrcheez

Sorry thought I made it clear in first post.. the radios are typically tuned to RTE. When I want to broadcast my own music I can do so without having to retune all the stations.

Will this be possible with this? http://www.ebay.com/itm/Home-FM-TRANSMITTER-100mW-500mW-Power-adj-76-108Mh-/271642045167?ssPageName=ADME:X:AAQ:US:1123&afsrc=1&rmvSB=true

Or is the RTE signal too strong?

Kensington

mrcheez wrote: »

Sorry thought I made it clear in first post.. the radios are typically tuned to RTE. When I want to broadcast my own music I can do so without having to retune all the stations.

Will this be possible with this? http://www.ebay.com/itm/Home-FM-TRANSMITTER-100mW-500mW-Power-adj-76-108Mh-/271642045167?ssPageName=ADME:X:AAQ:US:1123&afsrc=1&rmvSB=true

Or is the RTE signal too strong?

Not a hope, RTÉ FM networks transmit at anything up to 160kW of effective radiated power.
You might get a signal off your FM transmitter within a few feet on the receiving radio but no way it will cover the entire house, the RTÉ signal will simply swamp it out.

coylemj

Kensington wrote: »

Not a hope, RTÉ FM networks transmit at anything up to 160kW of effective radiated power.
You might get a signal off your FM transmitter within a few feet on the receiving radio but no way it will cover the entire house, the RTÉ signal will simply swamp it out.

There is every hope it will work, it all depends on where the OP lives. I have an FM radio and when I do an autotune to find the 10 strongest FM stations, not one RTE station comes up. I live less than 7 kms as the crow flies from Three Rock and RTE doesn't swamp out other stations, I have to manually tune the radio to receive it.

If RTE 'swamped out' other stations, they wouldn't need the 34 relay stations that are listed in the current 2RN frequency table.

mrcheez

hmm ... worth a punt for €55 I guess...

mrcheez

Kensington wrote: »

Not a hope, RTÉ FM networks transmit at anything up to 160kW of effective radiated power.

Just on this... I'm no radio expert but wouldn't a 100mW or 500mW signal be stronger than a 160kW signal in short range (circa 20m) ?

This is the tech spec on the FM transmitter...

power Supply: DC 9-14V (12V recommended)
Frequency Range: 76-108Mhz
Frequency Step: 100khz
Frequency Response 100-15000Hz
Frequency Stability: ±0ppm(-10°C to +60°C )
Antenna Design Rubber Antenna
Antenna Connector BNC type
Audio Input Interface: 3.5mm audio connector
Mic Input Interface: 3.5mm audio connector
Output Impedance 50 ohm
Distortion: <0.5%
SNR >70dB
output Power: 100mW/500mW±10%
Frequency Deviation: Less than ±75kHz
Tuning design method PLL Technology
Dimensions(L*W*H): 113mm * 88mm * 39mm

Fuzzy Clam

Even with the "capture effect", 1/2 a watt may not give you interference free reception throughout the house if you sit on an RTE frequency.
It doesn't state for sure but it looks to be mono only. It also doesn't state if the audio is pre emphasised. If it's not, the sound will be a little dull.

It may be a case of suck it and see.

STB.

Just get one of the small 15W TX's like a ST-15B from China. You can adjust the power on them (1W or 15W).

That little rubber aerial will be no good.

You need to stick some form of ground plane antenna or dipole up or you will burn out the board on them.

http://www.fmuser.org is the source of these. (there is cheap enough 7W with an adjustable 3db gain dipole included so you can match the frequency and keep the SWR low)

PS If you cannot adjust a preset on a radio you should mess not with these! Whilst what you are doing is fairly harmless its also technically illegal, so at least keep it away from legal frequencies.

@ fuzzy. They are stereo. Fairly wide.

jimceart

I think if your tx is tuned to a frequency it should block out any legit station in your immediate area. Having no aerial attached I think will achieve what u want without causing local disruption to the station which is broadcasting on the that freq.

mick masterson

jimceart wrote: »

I think if your tx is tuned to a frequency it should block out any legit station in your immediate area. Having no aerial attached I think will achieve what u want without causing local disruption to the station which is broadcasting on the that freq.

You will just burn out the transistor without a 50Ohm load / aerial .
Most modern transmitters have digital Phase PLL locking and tuning .

mrcheez

mick masterson wrote: »

You will just burn out the transistor without a 50Ohm load / aerial .
Most modern transmitters have digital Phase PLL locking and tuning .

and this affects what I want to do how? (bear in mind I'm not a radiophile) :rolleyes:

mick masterson

mrcheez wrote: »

and this affects what I want to do how? (bear in mind I'm not a radiophile) :rolleyes:

The transmitter will no longer deliver watt's / output power Dead .

mrcheez

So use the aerial to avoid this issue?

mick masterson

mick masterson wrote: »

The transmitter will no longer deliver watt's / output power Dead .

Yep a tuned antenna to the frequency or if you don't want much signal propagation you might use a dummy load resistor in parallel to achieve 50 Ohms over on your frequency. This saves transmitter from being damaged
if run on low power . The load heat's if too much power is used continuously.