RE: Howzat work then?

["Paul Gordon" <paul_gordon@xxxxxxx>]

Hi Kevin,

>
>	With a decent psu you <should> be able to get exactly the
>same quality as a battery. They are always invaluable anyway. M*****s
>did d  a very useful multi regulated unit once (probably when they
>were still an electronics store rather than a toy shop).
>	Are there any other wires attached t  the transmitter that go
>t  other electrical devices eg your audio sources - there is a
>possibility of earth problems. With any transmitter good earthing is
>essential. A wall wart should have a totally 'floating' output that
>needs to be brought t  chassis earth on the transmitter, as probably
>do all other inputs. If the transmitter becomes unstable you would
>see nothing.


Yes the TX board has a pair of phono sockets that I have connected t  my
PC's soundcard via a 60cm twin-phono t  3.5mm jack cable.


>	. RF pickup is als  potentially a problem but usually only at
>high power levels. A ferrite core on each cable will help fix this.
>It may all get better when it is in the metal (grounded) box.

Ah, that's a shame, - the choice of boxes at M***ins was s  piss-poor that
the only sensibly sized one was a plastic one. (which is what I got)


>	I don't know how the frequency is fixed in the transmitter -
>if it is crystal controlled or derived from a synthesiser then the
>input voltage should have little effect however other methods may
>well cause frequency instability if the supplied voltage varies at
>all eg at 50Hz.

I did think of that, and tested by retuning the reciever by about 1MHz
either side of my TX frequency (88.6MHz), in 0.5MHz steps. (which is the
smallest change I can make with this digital tuner....)

>	I assume als  as you say it takes a wide ranging voltage
>input that there is on board stabilisation of the supply so I am


According t  the documentation operating voltage range is from 6 t  16VDC


>surprised you are seeing this problem. It would imply that the
>troughs in the wallwart 12V supply voltage are dropping below the
>regulators threshold yet it works fine on a 9V battery. Unregulated
>wall warts tend to output way too much usually and rely on the
>(known) load to reduce them t  roughly the right level. Maybe the
>drawn power is too high for the wall wart. What is the current
>consumption of the transmitter ?

Not stated, so no idea...

>I assume the psu feed and the 9V
>feed used the same wires ? (not bypassing the regulator for the
>battery usage ?)
>

Correct. - I remove the battery and replace it with the various wallwarts
for testing.

Cheers.

Paul G.



_________________________________________________________________________
Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com.




____________________________________
Automated Home UK
http://www.automatedhome.co.uk
____________________________________

Your use of Yahoo! Groups is subject t  http://docs.yahoo.com/info/terms/