Help with Power Adaptor

[gazzy21uk]

I think if we all tried to use and modify stuff it will save the planet for our children. This go out and buy new stuff mentality is killing our planet, and the manufacturing industries policy of building stuff that will brake down at a set time and so keeping us employed making replacements so that growth is substained is a madness we are all waking up to.
I think I have bought so much crap electronics stuff this year it is untrue I would say unbelievable but I'm trying not to sound like victor But I have binned so much junk this year.
We should all think twice before buying a new product and think of our children because the manufacturers are not, that's for sure.
Now our Charlies saved not only his own money but also our future by reducing his carbon footprint"Bravo".

[Trashcooky]

Hi @Trashcooky, you obviously know your stuff!

You can usually tell if the original power pack was ½ wave by a dotted line ----- whereas a fullwave device shows a continuous line ____ and of course the voltage and current rating.

Most of the power adaptors I've got show both a dotted and continuous line on the spec label... does that mean they are both full and half wave compatible?

Regards

Excel

Your packs are only halfwave then Excel. The two lines (both dotted and solid) means the packs output a direct current flow regulated by an alternating current input. Most off the shelf units are half wave devices, but for audio uses unless they are of cheap quality, they should be full wave and smoothed. A dotted line represents the broken feed that ac produces due to the polarity change of 50 times a second in the UK and 60 times a second in the US. This means that there is a point in time where the output is actually zero - at the point of changing from the positive cycle to the negative cycle and back again as with alternating current. A fully rectified output power pack will normaly be clearly marked with a - and a + (i.e. 3v - ____ + ). As a point of interest most battery chargers you buy for your car battery are only half-wave chargers. This means that for 50% of the time (at the cycle changes) no voltage is actually flowing so a 2 hour charge only produces an actual peak flow voltage for 1 hour. If car battery chargers were made as full-wave devices, you could theoretically charge your battery in half the time. The halfwave packs cause a hum on audio devices because they are actually switching on and off 50 UK or 60 US times a second.

[blueeagle69]

Whoosh, and there it goes. Straight over my head
And I thought I knew a fair bit about electrics too.
I think I will pop off, and chew on the end of that power cord. It has pretty-colour cables

[admin]

Whoosh, and there it goes. Straight over my head
And I thought I knew a fair bit about electrics too.
I think I will pop off, and chew on the end of that power cord. It has pretty-colour cables

LOL!

[JCB]

Hi @Trashcooky, you obviously know your stuff!

Most of the power adaptors I've got show both a dotted and continuous line on the spec label... does that mean they are both full and half wave compatible?

I thought that meant DC, as opposed to a wavy line indicating AC output

John

[Trashcooky]

Hi @Trashcooky, you obviously know your stuff!

Most of the power adaptors I've got show both a dotted and continuous line on the spec label... does that mean they are both full and half wave compatible?

I thought that meant DC, as opposed to a wavy line indicating AC output

John

The continuous line means full wave rectification with no interruptions.
The dotted line usually means half wave rectification which is pulses of DC with zero voltage gaps.
Hence charging from a half wave charger takes twice as long as it is only supplying power half of the time.

[JCB]

Hi, not meaning to get contentious as a newbie here, let's check we are talking about the same thing. Here is an example of the symbol I am thinking of -
http://en.wikipedia.org/wiki/Direct_current

I was wondering how far half-wave and ful-wave rectification is relevant with modern switch mode power supplies. I was assuming that the PSUs we are using with Android tablets wopuld be smoothed DC output. WIth the introduction of cheap mains voltage power switching transistors, the modern lightweight adapter isn't using the traditional transformer into rectifier into smoothing circuit. The weight of the 50Hz mains transformer is dispensed with and the AC is switched into a high frequency that can then be voltage dropped by a lightweight HF transformer. Of course the low voltage high frequency power still has to be rectified and smoothed.

John