power supply interference with radio broadcast

[Renton Maclachlan]

Apologies Greg, I read 'wal wart' as 'wal mart'. I assumed Walmart may have had an electronics dept that supplied these sort of things.

At present I am trying all sorts of avenues. I now know more specifically what to ask for and will ring another shop today...

Thanks for your help...:-)

[Greg Miller]

Renton:

Dang, I'm sorry for the confusion. I didn't notice the typo until you mentioned it just now. "Wall wart" is our nickname for those fat little power supplies that plug into a wall outlet.

I share your frustration and I really wish I knew the name of some appropriate vendors in NZ. I don't even know anyone who's ever been in NZ, so I have no idea where to start from here.

And believe me, if I could find one online with a 50Hz input, I would send you the link.

Actually, while we're on that train of thought, what is your line voltage there? Wikipedia says 230V, 50Hz, but they're not always correct.

[Renton Maclachlan]

'Don't even know anyone who's ever been in NZ.' Man you've never lived! Pocket wonder world. Successive guments have been progressively wreaking the place (as seems to be happening just about everywhere in the West), but the land is something else...

Yep we're 230v...never thought about Hz.

Probably the best supplier around here is jaycar.co.nz followed by Dick Smith dse.co.nz

[Jim Andrada]

I'll second the comments about NZ - it's really lovely. When I worked out of Tokyo flogging IBM's storage products in Asia/Pacific I had at least one trip a month to NZ and absolutely loved it. I even took my nephew there for his 11th birthday. Did the farm stay thing near Christchurch for a week.Happiest sheep I've ever seen (particularly compared to the poor sheep who have to eke out an existence in the deserts of Oz)

[Renton Maclachlan]

Jim.

Unfortunately Christchurch has been shattered by a number of servere earthquakes over the past year and it is not the delightful city it was...people have left in droves, and sections of the CDB are in ruins...something like 5000 houses are to be demolished...many of the beautiful stone churches, including the iconic Cathedral have effectively been destroyed...every new big shake has liquifaction flooding some suburbs...cry...

[Jim Andrada]

Yes, I know what a mess it is. It must still be heartbreaking even after all this time.

These things quickly fade from the international news, but are still very real for all those affected.

I lived in Japan for quite a few years and my wife is Japanese and we watch NHK every day. From what we see here in the US, the earthquake/tsunami is "old news" but it still takes up about 20% of NHK airtime. Fortunately her family is from Southern Japan, but, just as I've spent time in Christchurch, my wife and I frequently vacationed in some of the towns that were demolished and many of those ghastly scenes were from places we knew.

Maybe the moral of the story is that wherever I go, bad luck follows!

[Greg Miller]

Renton,

Thanks for providing those names.

I just scanned Jaycar's online catalog. There are numerous 5V power supplies, but, by damn, they all seem to be switchmode! So I fired off an EMail to their customer service department, asking if they have any linear supplies hidden away.

If that draws a blank, I'll try Dick Smith next time.

[Chris Soucy]

Hi Renton..................

Didn't really understand your reference to a "USB Power Supply" plugged into you Ipod, so didn't really get too excited.

However, as this is rumbling on, may I suggest something?

Still not entirely sure of the "what is plugged into what" chain with this, but here goes:

Dive into Jaycar (they're cheaper than DSE usually) and buy a couple of ferrite torroids that are appropriately sized for the cable(s) being used, such that you can pass the appropriate power cable (s) through the torroid at least 4 - 5 times, wound tightly to the torroid ring.

That should kill any HF noise passing down the power cable, though it can be a pretty moveable feast.

I've tried running a battery fed CB system off a linear power supply of my own build (a damn good one too) and even that couldn't keep the bloody stuff out of the transmitter.

A few more details about cables and connectivity may give me a better insight into the problem.


CS

[Renton Maclachlan]

Thanks Chris

I got a couple of ferrite rings from Jaycar last saturday. I wound the cable through them as many times as I could get the usb plug through the hole and...there was not the slightest scrap of difference. So...they don't seem to work...

Soo...it's seems to be either a linear supply or an elcheapo laptop serving as a power supply...

Renton

[Steve House]

Originally Posted by Renton Maclachlan

Thanks Chris

I got a couple of ferrite rings from Jaycar last saturday. I wound the cable through them as many times as I could get the usb plug through the hole and...there was not the slightest scrap of difference. So...they don't seem to work...

Soo...it's seems to be either a linear supply or an elcheapo laptop serving as a power supply...

Renton

Uhhhhh .. or you could ditch the iPod completely and use a real, purpose-built audio recorder ..... Seems like you're going to a lot of trouble and expense to use what would ultimately be a marginal solution even if everything worked perfectly.

[Greg Miller]

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.

[Renton Maclachlan]

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?

[Greg Miller]

Originally Posted by Renton Maclachlan

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

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?

[Chris Soucy]

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

[Renton Maclachlan]

'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...