What are the 'new' Domestic 12vdc Transformer / power suppliers called ?

[Furkin]

Hi,
A long time ago, the old transformers used to burn out regularly, as they were left on 24/7 to power things (even though they'd been turned off).

You can tell the 'old' ones, because they are heavy (metals & windings etc), but the newer ones are a lot lighter, and don't burn out so easily.

Like a twerp, I can't remember what they're called !
Can someone remind me please ?

Of course they don't have to be 12v dc, they can be any size. Currently, I want to replace a 12vdc / 2A 3-pin plug (with 2-pin outlet): AB-4812167.

I may then look into changing all the transformers in my home.

regards
F

 

[davelx]

This'll be what you're thinking of:

https://en.wikipedia.org/wiki/Switched-mode_power_supply

(They still have transformers, just not heavy ones!)

Lots to choose from:

http://cpc.farnell.com/search?st=12v dc power supply

 

[ban-all-sheds]

Hi,
A long time ago, the old transformers used to burn out regularly, as they were left on 24/7 to power things (even though they'd been turned off).

You can tell the 'old' ones, because they are heavy (metals & windings etc), but the newer ones are a lot lighter, and don't burn out so easily.

There is absolutely no way that a (non-faulty) "old transformer" can burn out if left on 24/7.

Like a twerp, I can't remember what they're called !
Can someone remind me please ?

It largely depends on what they are meant to be used for.

"Modern" ones for ELV lighting are often called 'electronic transformers'. For LED lights there's a trend, I believe, to use the term "driver", although strictly speaking they may not be.

"Adapter" is sometimes used for the wall-wart type.

Of course they don't have to be 12v dc,

They do if that's what you need.

Currently, I want to replace a 12vdc / 2A 3-pin plug (with 2-pin outlet): AB-4812167.

Why?

What's it for?

I may then look into changing all the transformers in my home.

Why?


Also, can someone else this time take on the task of pre-emptively advising Furkin to completely ignore any pointless pedants who might pop up bleating about there being no such thing as "electronic transformers" etc.

 

[securespark]

often called 'electronic transformers'

Hide behind the sofa, I shall go and.

 

[winston1]

I may then look into changing all the transformers in my home.

That is a bad move. The switch mode supplies are actually less reliable, (can't think why the transformers burnt out, it has never happened to me). Also switch mode supplies are a source of EM interference (radio interference) which does not happen with transformers.

 

[winston1]

"Modern" ones for ELV lighting are often called 'electronic transformers'.

***

 

[333rocky333]

 

[ericmark]

Switch mode power supply, or pulse width modulated, or electronic transformer, or driver all have electrolytic capacitors in them so all have a limited life, a simple wire wound transformer and if DC a rectifier although they may have electrolytic capacitors they are not required for it to work so in theory they should last longer.

However the switch mode units often have over heat and over current shut down, so things like quartz lamps which when they rupture can cause ionisation in the bulb could over load simple wire wound where with a switch mode it auto closes down. However I have had a second hand 200 VA transformer in my loft for so 20 years and it's still going strong,

these seem to just go on and on.

 

[Furkin]

Thanks guys - yes, it was the 'switched mode' things I was thinking about.
But now i've read these messages, maybe I'll need to do some research before changing them all.
I was obviously misinformed before (not by a salesperson, so they had nothing to gain).

My immediate quest is to replace a 12v 2a one for a standard lamp with G4 bulb. It has 2-pin output - a pin & a flat plate - on a uk 3-pin plug.

It doesn't have to be the 2-pin outlet thing, as I can adapt the existing.

For this use, would a wound or switched mode transformer be best ?

 

[333rocky333]

What is the lamp wattage, most Electronic Transformers have a minimum load of 20 watt, though some modern stuff now has lower

 

[Furkin]

The lamp is a normal G4 (I have also imported some other types to try - SMC - COB etc,,,)
The original transformer states: AB-4812167 : 50Hz : 12V ~ 1.67A : 20VA. I think it's a common size.



I'm putting off replacing my other transformers for now. They all came with their own equipment, so must (!?) be the best for the item.
When/if they need replacing, I'll come back here to ask advice, which is always forthcoming and well appreciated.

thanks guys

 

[bernardgreen]

there's a trend, I believe, to use the term "driver", although strictly speaking they may not be.

A "driver" for LED lights controls the current that is driven through the LED elements. The voltage that appears across the output is NOT controlled by the driver, it is determined by the forward voltage of the LED element(s) that the current is bening driven through. With one element the voltage will be somewhere betweem 0.7 volts and 3.3 volts depending on the type of LED element. When 10 LED elements are connected in series across the poutput of the same driver the voltage will be 10 times ( 7.0 ~~ 33 volts )

A power supply for LED lamps supplies a controlled voltage to the lamp. The lamp consists of one or more LED elements and a driver that controls the current driven through the element(s).

 

[ban-all-sheds]

I'm sure there are some LED lighting systems which are powered by external constant-current sources.

 

[bernardgreen]

I'm sure there are some LED lighting systems which are powered by external constant-current sources.

Yes but not in the domestic market.

Several "lamps" can be connected in series with a controlled current driven through the series circuit from a single current source.

Each lamp has an LED element ( maybe more than one in series ) and a circuit to maintain continuity through the lamp if the LED element(s) goes open circuit. There is no driver in the lamp.

 

[aptsys]

The lamp is a normal G4 (I have also imported some other types to try - SMC - COB etc,,,)
The original transformer states: AB-4812167 : 50Hz : 12V ~ 1.67A : 20VA. I think it's a common size.



I'm putting off replacing my other transformers for now. They all came with their own equipment, so must (!?) be the best for the item.
When/if they need replacing, I'll come back here to ask advice, which is always forthcoming and well appreciated.

thanks guys

The only benefit you're likely to see is maybe slightly higher efficiency with electronic transformers, but it'll be negated by the cost of replacements.