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Darkmatter
Posted: Thu Apr 21, 2005 12:00 am Reply with quote
Forum moderator Joined: 21 Mar 2005 Posts: 1237
Ummmm?.that depend on where the problem lies. To be honest, you only ordered yours today, so I would hold off buying anything right now. Plug it in as see if there?s a problem ? most people will be fine right out of the box.
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sneeks
Posted: Thu Apr 21, 2005 12:08 am Reply with quote
Regular contributor Joined: 20 Apr 2005 Posts: 62
The only thing i'll need to buy is a new indoor aerial. I bought a Pioneer freeview box for the bedroom at Christmas and my standard aerial was terrible so I replaced that and all worked fine. Unfortunately it's that one i have in the livingroom but never used it often as i have the free channels on Sky.
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Darkmatter
Posted: Thu Apr 21, 2005 12:26 am Reply with quote
Forum moderator Joined: 21 Mar 2005 Posts: 1237
No problem?..One thing I would recommend before you buy a new aerial is to try your freeview box and aerial with your main TV ? just to get an idea of reception quality downstairs, as the digital TV signals are a lot weaker than the old analogue ones.
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sneeks
Posted: Thu Apr 21, 2005 9:27 am Reply with quote
Regular contributor Joined: 20 Apr 2005 Posts: 62
I'll be testing it tonight with both the newer aerial from the bedroom and also the older one that is in the livingroom. I'll let you know how i get on and if required ask for some advice on which sort of indoor aerial would be best.

The standard bedroom aerial achieves a 70-80% signal strength and 100% quality consistently.
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kieronishere
Posted: Sat Apr 23, 2005 9:54 pm Reply with quote
Regular contributor Joined: 23 Apr 2005 Posts: 41
It's way more sensitive than my Nokia 221T. It tuned to my local transmitter but also a far off one as well giving two of every channel. Had to turn off my booster and split the aeriel signal so that it would only tune to the local one. Now get nearly 100% strength and 100% quality with booster.
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Normsthename
Posted: Sat Apr 23, 2005 10:45 pm Reply with quote
Frequent contributor Joined: 12 Apr 2005 Posts: 118
I also live in an area that cannot get freeview....... but I can.
I get 78 channels in total (51 TV and the rest radio.
Channel 5 is the worst signal where I am, and I initially had very bad breakup etc, so as advised I got a signal booster, and it is fine now. On Channel 5 I get 99% Quality and 70% Signal, this is the worst, on the better channels I get 75% signal.

Hope this helps.

Andy
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phil.s
Posted: Tue Apr 26, 2005 4:13 pm Reply with quote
Regular contributor Joined: 25 Apr 2005 Posts: 46
Anyone know if there is a masthead amplifier that can handle the 5v which the toppy can output ?

All the masthead amplifiers I can see on maplin.co.uk require a separate psu which sends 12v up the coax lead.
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malc
Posted: Tue May 10, 2005 1:20 pm Reply with quote
Frequent contributor Joined: 08 May 2005 Posts: 1380
On the other hand, since the toppy already runs hot is it a good idea to use the 5V anyway? Taking current from the 5V supply would increase the dissipation in the toppy so I think an external PSU is a better bet.
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Darkmatter
Posted: Tue May 10, 2005 6:28 pm Reply with quote
Forum moderator Joined: 21 Mar 2005 Posts: 1237
That?s a difficult one to call. It could well make the Toppy run cooler - the efficiency of the PSU increases as the load increases. With the load being external, it?s heating effect will be outside the box, and with less heat from the PSU, you could well find the temperature of the Toppy goes down. However, we?re talking relatively small amounts of current, so any reduction is going to be slight.
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malc
Posted: Sat May 14, 2005 10:12 am Reply with quote
Frequent contributor Joined: 08 May 2005 Posts: 1380
You're mistaking efficiency for losses. Yes efficiency increses in a switch mode PSU (or even a linear) as the real load increases but that 's because the PSU has a standing loss for the power required to drive the PSU electronics.

It's easier to explain with numbers so say it takes 1W in the PSU circuit and there is 1W of load, eff=50%. Increase the load to 9W and eff=90%. But in terms of losses there is now 10W being dissipated in the toppy instead of 2W, even though the efficency has gone up.

With 5V being taken by an aerial amp the loss there is outside the toppy, however, the PSU will have some losses that increase with load as well as a fixed standing loss. Hence you will get more loss in the PSU with 5V supplied to an aerial amp.

I'd agree it might not be much power but since 12V supplies are cheap enough why do it? Also, sending 5V up the aerial cable to the roof would seem a good way to possibly introduce interference into the toppy so I wouldn't do it for that reason either.
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Darkmatter
Posted: Sat May 14, 2005 12:42 pm Reply with quote
Forum moderator Joined: 21 Mar 2005 Posts: 1237
You?re almost there. You have the right bits, just not connected together correctly.

Obviously the numbers you use are outside of what our Toppy can supply 100mA @ 5V = 0.5W, but if we stick with them by way of example ? if the PVR were to take 1W normally, and 9W with the amplifier attached, and the efficiencies were as you state, there would be no temperature rise inside the PVR.


Normal condition: 2W input power @ 50% efficiency give 1W of output power, and 1W of waste heat

Supplying amp: 10W input power @ 90% efficiency gives 9W of output power, and 1W of waste heat

In both cases, the PVR requires 1W of power to operate its circuitry, and this (the majority of) eventually becomes turned in to heat. So, the heat inside the PVR consist of 1W from the PSU, and 1W from the circuitry ? that?s 2W of heat ? in both cases ? with, and without the external amp.

As you rightly say, the 8W (5V) supplying the external amplifier is outside of the Toppy?s case, so the heat generated in the load will not increase the temperature of the Toppy (because it?s in a different place).

Having said all of that, it?s all fairly academic. We would have to obtain the characteristics of the PSU, and run a test to be sure: As I point out in the opening sentence of my OP ? it?s difficult to call whether the temperature inside the Toppy will increase, or not.
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malc
Posted: Sat May 14, 2005 2:32 pm Reply with quote
Frequent contributor Joined: 08 May 2005 Posts: 1380
The power you can take from the aerial supplu does make it somewhat academic, assuming that the toppy isn't derived the 5V off an internal 12V suply of course. However, it will increase the power loss inside the toppy, all be it not by much. You can't take more power from a PSU and not increase its losses. BTW, perhaps I should add I design electronics for living, PSUs included.

I would be more wary of using an expensive item, the toppy, as a power supply for a long bit of cable which ends up on the roof. I find it more comforting to have a cheap PSU in the line instead.
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Encrypter
Posted: Tue May 17, 2005 5:43 pm Reply with quote
Frequent contributor Joined: 09 Apr 2005 Posts: 137 Location: Bristol, UK
phil.s wrote:
Anyone know if there is a masthead amplifier that can handle the 5v which the toppy can output ?


No, but on my travels I have come accross this if anyone fancies trying it:

http://www.oneforall-int.com/english/products/soundvision/sv-9350.htm

This would appear to accept the Toppy's output voltage, but not sure how good an aeriel it is.

(It is supposed to be an outdoor one according to the specs).

That is of course if you can find one Smile
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