DAB radio

trog said:
I had planned to use it to replace the FM radio I keep in my bathroom. Being
a bit of a miser I like to use rechargeable batteries
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One option is to power it off the mains plugged into the shaver socket using an inexpensive adaptor.
 
prpr. What about 10kW electric showers then. How does that sit with the 'no mains' rule?

trog. Most stuff will run on lower than optimal voltage (think batteries going flat). It was a serious suggestion to try. Just find some cheap and cheerful way of inserting some sort of electrical conductor in place of a battery and see if it works.
 
Thanks all for your advice. No shaver socket anyway. Mike0001's 2 charger option seems to be the best bet.
 
I find it difficult to believe a device designed to run on whatever voltage will run acceptably on 80% of that voltage. Easy enough to try it though (just find something conductive to fill the gap of one cell).
 
Trev said:
prpr. What about 10kW electric showers then. How does that sit with the 'no mains' rule?

trog. Most stuff will run on lower than optimal voltage (think batteries going flat). It was a serious suggestion to try. Just find some cheap and cheerful way of inserting some sort of electrical conductor in place of a battery and see if it works.
Click to expand...

That was quick Trev, cheers. Does that mean I could just charge 4 batteries and use a flat 5th? Pushing my luck but could the 5th be a
standard new battery that could just be left to drain down and still serve the purpose when flat?
 
trog said:
could the 5th be a standard new battery that could just be left to drain down and still serve the purpose when flat?
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If you want a high resistance in series with the remaining four cells, then fine - carry on.

Trev said:
What about 10kW electric showers then. How does that sit with the 'no mains' rule?
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You know full well the rule is no non-isolated power sockets. Permanent installations in an approved manner are exempt (otherwise you wouldn't even have lighting). Shaver sockets have a mains isolating transformer in them, and if you try to draw too much current the transformer saturates (thus limiting the output).
 
I doubt the only use 4 will work, or not for long. If the device is designed to run on standard cells (~1.5V) then it may not be very good using rechargeables (~1.2V), e.g., by needing more frequent recharging than you might expect.
So using just 4 out of 5 not only are you losing 20% as BH says, but possibly another 20%.
 
I covered that by the word "acceptably". Tuner circuits, in particular, lose discrimination as the operating voltage drops. Gain stages (an essential part of any RF or analogue audio circuit) are designed to operate over a particular supply voltage range because various points in the circuit have to have a specific bias voltage applied to them, and the circuit is designed to provide that bias voltage from the supply voltage. Probably the most telling point is the unusual use of five cells to power it (I've never come across that before) - if it could have been designed to run on four cells, it would have been!
 
My main option is to play music / radio on my bedroom stereo turned up *LOUD* and keep the doors open. :)
 
More food for thought hmmmm, looks like its 2 or 3 chargers then (plenty of 2's available cheaply with 4 being much rarer). At present I use 4 rechargeable AA's in the old FM radio, they are about 4 years old and I only need to charge them once every 3 months so more frequent charging is not much of an issue, volume is never cranked up due to the ungodly hours I have to perfom my daily ablutions and its only used for about 5 or 6 hours a week. Even if the DAB is a real energy guzzler the price of 6 R14 Duracell's makes rechargeables + chargers a better option. Yes 5 batteries is an odd numer, I would have preferred 6 if it made them last longer as 6 is the number you need to buy. Thanks again.
 
I just looked at the mains lead supplied and it has an AC/DC adapter that outputs DC 7.5V 2A Max. I wonder if there is such a thing as a rechargeable powerpack that I could use to power it instead of batteries.
 
I think my preferred solution would be to use AAA NiMH cells in C adapters. The NiMH cells are readily available, as are chargers for AA/AAA cells. The down side is that the terminal voltage would be 6V instead of 7.5V, but that would be a steady 6V instead of a declining 7.5V.

There's no difficulty knocking up a holder for cells externally and connecting to a DC plug; in that case I would go for a gang of six AA NiMH (7.2V)

http://www.maplin.co.uk/p/6-aa-battery-box-hq01b
http://www.maplin.co.uk/p/pp3-snap-battery-clip-hf28f
http://www.maplin.co.uk/p/maplin-25-x-50mm-dc-power-plug-l49ay *

* this is just an example - I don't know what size plug you need. Parts are also available elsewhere (eg eBay).

Always charge the cells separately - never charge them in series (the way they are connected in the battery holder).
 
trog said:
Yes 5 batteries is an odd numer, I would have preferred 6 if it made them last longer as 6 is the number you need to buy.
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Yes, 5 is certainly an odd number, but I personally would ho for the even number 10, 5 in, 5 ready charged to swap out. Eneloops if you can find some that are not fakes.
 
Damn! I replied to BH soon after he posted, no reason for it to be deleted so maybe my error. Anyway this was it as best I remember...........................

@BH. Now we are getting somewhere. I already have some new AAA rechargeables from Maplins and a couple of Uniross chargers that both take 4 x AAA's
"Always charge the cells separately - never charge them in series (the way they are connected in the battery holder). "
Are you saying that I should only charge 1 battery in each charger at a time? If so what is the reason? Also why AAA's in C adapters rather than AA's Thanks for your help. AFK for a while but will be back later for more education. ( Trev, that means away from keyboard).

mike 10?????? Under the present government such expenditure is not possible, I am not a member of the DUP
(Trev, thats Democratic Unionist Party)
 
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Deleted. I doubt it. Your error.
trog said:
Are you saying that I should only charge 1 battery in each charger at a time?
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No. Properly designed chargers actually charge batteries individually. That's why they often have 4 LEDs on them to indicate the state of charge of the individual cells.
trog said:
Also why AAA's in C adapters rather than AA's
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I think that's what he meant.
As far as abbreviations are concerned, I have no problem with commonly accepted ones, it's the txt spk ones that I have problems with. LOL. Jeez, it wasn't that bloody funny.:roflmao:
 
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