Mid range FM transmitter

KrakityJones

Hi,

Apologies if this isn't the right forum to ask in. Would anyone have any idea if you are allowed to use a medium strength fm transmitter in ireland for personal use?

I'm looking at trying to make a cheap multi-room music system, I know you can get small fm transmitters for ipod/car but the range is only a couple feet. I've seen long range ones for sale online but figure it might be technically considered a pirate station (and would probably be taken by customs on the way in). I just want it to be strong enough to cover a house. I've looked online and that seems to suggest even those small ones are illegal. I'd chance spending 80 quid for one from china but don't fancy getting in trouble for it.

Thanks

PauloMN

Technically they are illegal, only the very low power ones like those you describe are permitted.

You could use a video sender with a few receivers which should do what you want, just don't use the video part. These are perfectly legal and will give you better results than a dodgy FM transmitter. Some of the video senders are quite cheap, like the ones you get in Lidl. I got mine on special in Maplin years ago and I was able to buy an extra couple of receivers.

watty

The Video senders use two separate audio channels. So quality is a bit higher.


But all the CE FM TX I have cover nearly the whole house when I'm using a good FM radio. I check first all over the house that the channel / frequency is empty. The "auto scan" FM radios are useless for these.

Also use one that has a 5V jack. If the power cable and the audio cable are both 0.5m to 1m the signal is better too. The external 5V is an "earth" (even if the PSU has no earth). Make sure the 5V PSU isn't producing radio interference on LW, MW or VHF, if it does it's likely too cost reduced and may also be a fire risk. Some cheaper FM TX only take a single 1.5V cell even though the internal IC needs at least 2.75V. Even the twin AAA or AA types can't use up the whole battery as the voltage will be 3.3V fresh dropping to 1.8V for end of life. So get a model with a 5V socket. They will work about 3.6V to 6V as they use a "low drop out regulator" for 3.3V. Some old 5V phone chargers are really 7V to 9V at low current.

I have a +5V plug and wire fitted to the 5V inside two of my Satellite receivers so I can have TSF Jazz and R4 (or any other pair of stations on 28E, 19E, 13E or 9E) and no extra PSU or batteries. A 0.5m RCA/Phono plug lead to extend to audio in. One Sat box has no separate audio out so I use a SCART to RCA/Phono adaptor on the 'VCR' SCART and a 20+ year old Philips 12" RGB monitor off an Atari that's only used occasionally as the sat box shows channel number.

KrakityJones

Cheers for the replies,

I'll check out the video sender idea, that sounds do-able and has the added bonus of better quality by the sounds of it

Thanks for that

Tallaght Twin

Search 'Whole House FM Transmitter' from the US. They sell for about the budget you have. Nice little units, good quality, and Recently improved with version 3.

watty

They are also illegal and irresponsible.

The perfectly legal locally bought in Ireland models under €10 CE marked units will cover a whole house if connected properly and a decent VHF-FM radio is the receiver.

Tallaght Twin

Watty, what's your opinion/view of the whole house FM transmitters designed and sold by Michigan outfit TAW Global LLC?

watty

If it's a CE product then OK.
Almost nothing specially produced for the USA (FCC is not CE) is legal in Europe.

The €6 (local Irish not even ebay) or less CE marked LEGAL FM TX for MP3 player to Car Radio are legal for say a media box to any FM Radio and have the same 150ft (50m approx) range!

At $125 it's grossly overpriced. Similar spec (many with CE) are under €10 inc postage on eBay. The external aerial connector makes it illegal in all of EU!

I'd wonder is that product legal even in USA as they make no mention of FCC (an FCC certification is mandatory in USA just as CE approval is mandatory in EU).

For a licensed Band II transmitter (e.g. Hospital, college, community or BAI licensed station) only ETSI certified equipment is allowed.

Comreg has Irish / CE specs for personal "licence free" FM transmitters. The CE certification is actually a licence so anyone can use it. The "whole house FM transmitters" by TAW Global don't seem much different range to legal CE models and x10 the price and illegal in EU.

I have bought and tested 4 brands priced €2 to €12. The €12 model use same cosmetics, electronics and features as some sold previously in HMV with better known brand name at €80. There are only two different kinds of RF IC used (same quality and range) in CE approved models. One has pins direct to a switch to set a small number of channels. The other IC is cheaper and has only a I2C serial data port. It connects to a small CPU with LCD controller built in so any channel can be selected. A variation of this not worth paying for is a model with also an I2C controlled poor quality single chip FM radio (the kind in €8 digital portable clock radio) used to scan for a vacant channel. Because it's such a rubbish radio you are better with cheaper manual only model and using the radio that will be used to receive to find a clear channel where it will be used!

RDS MP3 TAG
As an experiment I added a PIC with USB port (implementing Serial Emulation) and a 2nd PIC cpu implementing an RDS encoder. Then on PC with a Winamp to Serial (com 9, really the PIC USB) I could have the MP3 tags on the radio. Wiring up to the €2 CE FM TX didn't require any modification, just a 3 pin connection to existing circuit points to take out 19kHz pilot, ground return and RDS carrier via 100K resistor to where the L+R audio, Pilot and 38KHz L-R subcarrier is fed (the external varicap of the VHF oscillator).

Tallaght Twin

Watty, thank you for the very considered reply. Your RDS experiment sounds interesting. Unfortunately I don't have the same level of skills to emulate, but would sincerely love to.

watty

I might do a kit.
Or possibly this might be a feature built in to some gadgets in future. Sadly there is no cost effective way to connect Bluetooth stereo out of smart phone to a HiFi or FM Radio. A Bluetooth stereo gadget with built in FM TX and RDS with TX channel set by phone app ought to be under €20 in quantity and work with MP3 playback in any phone. More sensible that a stupid overpriced "Dock". Almost every Stereo speaker "Dock" I have seen is no better loudspeaker and audio quality than a sub €15 Chinese radio (e.g. Tesco Kitchen Radio).