Re: power supply interference with radio broadcast
 

Renton,

I sent an EMail to Jaycar. They answered (very promptly) saying they don't have an appropriate linear mode power supply. They recommended I try a place called Tradetech.

I sent an EMail to tradetech, and so have have received no reply from them.

--

OK, to satisfy everyone's curiosity, let's get a picture of the whole rig.

You have an iPod. You are using it to feed some sort of radio transmitter, right?

How does the transmitter get its power?

--

OK, another idea. Are there any technical schools (trade schools, or whatever you call them) near you, or even regular high schools that might teach some electronics courses? If so, contact the instructor(s) and explain why you need a linear regulated supply. It would be a very simple design/construction project for any high school class.

You need 6 parts: power transformer, diode bridge, two input filter capacitors, one linear voltage regulator (7805, LM340T-5, etc.), and one output filter capacitor. Really, a high school project at most.

Re: power supply interference with radio broadcast
 

Thanks Greg for bending over backwards on this. Much appreciated...

How is the transmitter getting its power? You guessed it. From a linear power supply!!!

...but not one that puts out 5v...(everything from about 3v to 'whatever, but not 5v) :-( ... I've forgotten what volts the transmitter takes...

I have another one of same...spare.

Was thinking. The ipod needs 5v...I believe. As I understand it, the mains power is to charge the battery. What would 4.5v do? Anything? Charge the battery?

Re: power supply interference with radio broadcast
 

I feel as if this is some sort of comedy program. You keep saying you don't know where to get a linear regulated power supply, yet it now comes to light that you have two of them. Have you, by any chance, called the place that sold you those?

How would a 4.5 V supply work with an iThing? I have no idea.

I belong to the "anything but iThings" school of thought. I have portable recorders by MicroTrack, Tascam, Sony, Archos, iRiver, Sansa, and a few that don't even have brand names on them. No iStuff for me. I pay for performance, and nothing else.

What about a tech school or high school nearby? Have you explored that option that I suggested?

Re: power supply interference with radio broadcast
 

Hmm, a second linear power supply?

What voltages DOES it put out, apart from NOT 5 volts?

If it puts out anything within a country mile of 5 volts - 6, 7, 9 etc this is doable, if a bit messy, if you're soldering skills are zero.

A simple and cheap silicon rectifier diode (1N4001 etc) will drop .6 volts if forward biased. Put in series with, say, a 9 volt supply you need 6 to drop 3.6 volts, taking you down to 5.4, which is close enough.

Else, building a simple voltage regulator using a 7805 as previously mentioned is a doddle for even the most ham fisted with just a bit of care, though it's probably possible to buy a kit that does the same job.

Else, pack it in and go with the "build a better mouse trap" approach suggested by Steve.

Gotta ask, how do you get a license to run radio stations without knowng anything about electronics? :)


CS

Re: power supply interference with radio broadcast
 

'Gotta ask, how do you get a license to run radio stations without knowng anything about electronics? :)'

Low power (max 1 watt) free to air. Two parts of the fm band. 87.6 > 88.1 and 107 something to something...

This is the first hiccup of this sort in 10 years, All the others have been equipment failures...

Re: power supply interference with radio broadcast
 

Geez, and there was me thinking 88 - 108 Mhz (a la the UK) was sacrosanct for the music stations, just goes to show, you learn something every single day.

No nearer to solving your problem though, sorry to take the thread off at a tangent.

What's it to be -

another linear regulatr attached to the spare one you have?

A new LR that O/P's what you need?

A total rebuild of the workflow?

Where are you in NZ BTW, 1 Watt doesn't get you far on the West coast of the South island?


CS

Re: power supply interference with radio broadcast
 

Just had a brain wave tonight... about a guy who I know can help and would love to...and I know has knowledge re ipods...

Re: power supply interference with radio broadcast
 

Glad to hear you finally thought of someone local with some knowledge of electronics.

Anyone with more than a basic high school knowledge of electronic circuits could solve this for you in about an hour. No smoke. No mirrors. No magnets. Just good old elementary electronics.

Re: power supply interference with radio broadcast
 

I was in my local second hand store this morning "Cash Converters" they had a box full of old phone chargers, computer power supplies, and plug packs from toys and video games etc.
Voltages range from 3v AC to 24v DC and every thing in between and several at 5v DC and by the weight some had transformers in them. and ALL............. $2 EACH.

Re: power supply interference with radio broadcast
 

Hmmm...now that is an idea. We have a 'Cash Converters' just down the road...Thanks!

Re: power supply interference with radio broadcast
 

Just be absolutely sure the output voltage is regulated! You don't want to fry your iThing.

Take a digital voltmeter with you when you dig through those old, relatively unknown, power supplies. If the output is much more than 5.1 or at worst 5.25 volts, don't buy that one.

And if you're going to wire a USB connector to it, it goes withotu saying that you need to be very careful of polarity and correct pinout.

Re: power supply interference with radio broadcast
 

I don't know how your going, but had another thought is get a plug in 12v car lighter adaptor for the ipod. It would have an inbuilt regulator to cope with varying car voltages 12-13.8v then feed it from a 12v DC transformer power adaptor that should be easy to find.

Re: power supply interference with radio broadcast
 

Thanks Brian. I haven't got there yet. Have talked to a friend with clues and contacts and hope to talk to someone tomorrow. I'll mention your idea.

Renton

Re: power supply interference with radio broadcast
 

Well, the car lighter adapter most likely has a switch-mode regulator in it. And most 12V "transformer power adapters" these days have switch-mode regulators in them. So you're trading his present problem (one switch-mode regulator) for twice as much potential problem (TWO switch-mode regulators). I fail to see any advantage in that approach!

One NZ vendor (tradetech) told me that NZ has power efficiency regulations in place, which prevent them from selling anything except switch-mode regulators at this point in time (with very few exceptions apparently).

So I think the previous suggestion of going to a used-stuff store (or yard sales, or wherever) with a voltmeter in hand, might be the only option *IF* he wants to buy locally.

Of course other countries might have other regulations, if he wants to import. I have a box of old linear supplies here, but they have the wrong input specs: USA is 120v/60Hz, whereas NZ is 230v/50Hz. He might find something appropriate from another European country. In that case, he'd have to change the original AC input plug for one of the NZ style... I doubt if he has the technical expertise to do that.

The OP apparently hasn't done anything about this in a week's time, so it doesn't appear to be terribly urgent.

Re: power supply interference with radio broadcast
 

I certainly don't have technical expertise in this area, but I am pursuing it with people here who do. I am in their hands.

While it is not crashingly urgent, I want to resolve it as quick as possible because of the PR with the owner of the house where the gear is.

Re: power supply interference with radio broadcast
 

The 12v adaptor would have only a 3 pin voltage regulator and some resistors in it as you are only working with low voltage DC volts. (not switch mode)

Just a little off subject... but are you transmitting music or chat type radio or some other, what is the range of the transmission and have you had copyright problems with music content (if any).

Re: power supply interference with radio broadcast
 

I've finally connected with someone who knows exactly what is needed and why, and is prepared to fix something up for me - a 5v linear power supply, which some here have suggested, which he has some of apparently. So problem may be solved next week.

RE your off topic question...I run a prerecorded 82 hour program (at the moment - though I have about 15 more hours available to go on to the program). The program is looped so runs 24/7/52. It sounds just like a conventional station though without time or geographic indicators. I'm the host and the program consists of serious documentaries about life the universe and everything focused on origin issues. I have about 480 music tracks without repeats of a wide variety of genre, most played in blocks of four back to back, between docos. I'm covered for copyright through paying a special annual fee to APRA, for low-powered non-commerial radio stations. NZ has several parts of the fm band set aside for low power (max 1w) free to air broadcasting. Range is about max of 10km...I have been on the web and need to get back on...

Re: power supply interference with radio broadcast
 

You might think so, but that's not necessarily the case. I have seen some (marketed for use with cellphones) that seemed (based on the parts I saw inside) to be some sort of switcher. No transformer, mind you, but apparently some sort of PCM switcher that ultimately charged the output cap to the desired voltage (I don't recall whether it was +5 or something else) by use of variable pulse width.

Even though the input is +12 and not +180, I suppose it still runs cooler and is more efficient than a linear, although it may seem like a minor point at that low a voltage.

Re: power supply interference with radio broadcast
 

What a great opportunity! Too bad the FCC didn't think of that when they allocated the FM broadcast frequencies here in the USA.

Re: power supply interference with radio broadcast
 

The FCC has Low-Power FM. (LPFM) One still needs a license to broadcast legally though of coarse. In fact I worked (audio) on a news show piece about it about eight or so years ago for NBC when the classification was still in congress. One of the main supporters was Sen. John McCain R-AZ . I don't recall the max. transmission wattage or other technical details though but I think with all favorable conditions, the range was about 5 miles at best.

Re: power supply interference with radio broadcast
 

The primary info for LPFM is at: Low Power FM (LPFM) Radio Service * * *(FCC) USA (imagine that)
The power limit is 100W.
There are currently 955 licenses (they may not all be on the air.
IIRC, the application window hasn't been open for several years.
Not that would do any good, as the FM spectrum is pretty much saturated in most larger cities.

There is also "Part 15" where power is limited to 100mW (1/10 W) and range is effectively a few hundred feet. You must not interfere with licensed services, but no license is required.

Re: power supply interference with radio broadcast
 

Yes, I'm aware of both of those options. But it sounds as if the NZ plan might be better.

Our LPFM licenses are largely being scarfed up by "religious" stations (e.g. the Joe's Garage Church of the Holy Smoke, etc.), conning the faithful believers out of enough money to run the broadcasts (and probably slip a little into the broadcasters' pockets as well), crowding the airwaves with content that is frequently syndicated and redundant, not to mention any of the political issues. IMHO a lot of these religious broadcasters have been a huge legal scam going back 50 years or more.

The Part 15 rules don't allow enough power to really cover any significant geographical area. Meanwhile, they do allow lots of $10 "modulators" that people use to feed their satellite radios, etc., into their FM receivers, thereby muddying up random FM channels (since Part 15 has no frequency limits) and ruining any chance for FM broadcast DX.

Re: power supply interference with radio broadcast
 

My stations are funded by myself and I receive no money from them whatsoever, in fact it costs me. What little advertising I carry is of no financial gain to myself - I don't charge for putting it on - and is there simply because I choose to put it on for the producers to benefit from. My stations are run to promote a message not make money...

Re: power supply interference with radio broadcast
 

Renton, I think that's wonderful, and I wish it were like that in this country.

Unfortunately, a 100-watt license has enough coverage to make it tempting and competitive as a money-making entity. And the Part 15 unlicensed transmitters are becoming a blight all over the FM band. The FCC made it bad enough several years ago, when they authorized first-adjacent channel spacing, without narrowing the transmitted bandwidth. Splatter, coupled with wideband receivers, has created a real mess. Now as the RF people retire, the FCC is being taken over by IT people and lawyers, so any reasonable broadcasting measures will probably never be implemented.

Re: power supply interference with radio broadcast
 

Our free to air licence has a max output of 1 watt not 100 watt...so it is very localised...max about 5>10km range depending on location of aerial. At the mo my original station is coming off virtually the top of a high hill at the centre of the population area so get about 75% of my small city - hills block the signal.

There can be an issue of interference with other stations and so there has to be a .1 separation in the frequencies 87.5, 87.7,87.9, 88.1

Only four stations can satisfactorily fit at any one place on each of the band sections made available, and it is all voluntarily controlled. If there is space on the band, anyone can go on it, and so long as you're broadcasting, you have the frequency. Major centres generally are filled up but small towns have plenty of options available apparently...

The hardware side of things is a piece of cake compared to producing a program. To produce my present 82 hour program would have taken me hundreds and hundreds of hours...6-7-800?...all in my spare time. I have about another 10-15 hours of material that could be added but I'm onto a major video production so it won't get added for months. That's no issue however as 82 hours is a hang of a long time for the program to loop. It's been running 18 months or so now - perhaps 2 years. I hear stuff on it I had forgotten I had put on!!! I think I have something unique in the world...

Re: power supply interference with radio broadcast
 

Yep, Renton, I think a 1-watt license is a great solution! It allows you to cover at least a "small community" so it's worthwhile to run such a station. It encourages public use and "free speech" on the airwaves, which is good, since the airwaves allegedly belong to the people (at least that was the original concept here, up through our Communications Act of 1934, although recent FCC actions have largely diluted or removed the concept of perpetual public ownership).

And by setting aside a certain part of the spectrum for these 1W allocations, you avoid the problems we have here with the "Part 15" very-low-power stations which can still produce enough RF to interfere with FM broadcast DX reception. (A local health center, which broadcasts their exercise music on 104.5MHz, prevents my listening for any distant legitimate stations on 104.3, 104.5, 104.7 MHz.)

There are a lot of other problems with the LPFM allocations here, and the channel spacing, but I won't go into that here.

So yes, I think NZ has come up with a much better solution.

And kudos to you and anyone else who is willing to invest enough time and energy to run such a station at your own expense. I do believe in free speech. 8-)

Re: power supply interference with radio broadcast
 

I bought a 1w FM transmitter off eBay and it works well on the occasions I have used it... I don't have a license and never even tried to get one. The times I have used it for wouldn't have mattered anyway.
It worked well as a 2 channel radio mic transmitter for about 2km in a forestry area at a car rally and I use it regularly as an FX mic transmitter on the starting gates for horse races, most of those tracks I work at are well out of town.
I work on the attitude if some one does come across the frequency, then works out what the sound is, then finds it.... I would have finished the job and out of there.
I have also used it as an IFB feed for some rowing championships.
In Australia they are used for things like Drive in movie theatres (and listen on the car radio), Real Estate sales info in new housing estates, Localised radio for outdoor sporting events like car and bike racing. One of the small towns nearby do a wonderful Christmas lights display with all the houses up in lights, run a Low Power FM TX for music of the season.

Re: power supply interference with radio broadcast
 

Just thought folks may like an UPDATE on this radio interference issue...

The problem definitely was the switching power supply for the Ipod...

After chasing a rabbit around for awhile, distilling all the advice I was getting from kind people all over the show, I finally got a 5v linear power supply out of Hong Kong (They seem as rare as hens teeth in NZ).

On Monday this was connect to a USB lead and I installed it tonight and the problem is solved.

There was a potential issue discovered on the web that fourth gen ipods will not charge if only the power wires are connected - a 'something er rather' reputedly needed to be installed across the data wires, but as it turned out, this was not necessary.

We could have got another power supply, one that could be switched between various voltages and put a different sort of 'something er rather' in the cable to limit a higher voltage output down to 5v, but as I got a 5v, one that wasn't needed. Ipod power input is limited to 4.75v > 5.25v.

So...thanks everyone for all the help given in tracking down and solving this issue...