G`day Folks,
                 Does any one know if there is a 240volt transformer available with the same output as one AA battery.                 
 In other words…….1.25volts @ 100 milliamps.

Cheers Gormo

Brian, first
AA battery is really a cell,  a battery comprise 2 or more cells. AA , as most single units,  are a nominal 1.5v - brand new may read 1.6 & will drop under a normal load.
If the load is 100 mA, then the supply should be capable of at least 150-200 mA - a supply of the same output in current as the load requires, means it is working to its maximum & is not ideal.
 
Second , I do not know of a specific transformer outside of many convertor/regulators from an existing DC supply or one like this
http://www.ebay.com.au/itm/Ex-Pro-Variable-Voltage-AC-DC-Power-supply-Regulated-1-5v-12v-DC-2250mA-2-25A-/370986404238?pt=UK_ConsumerElectronics_PowerAdaptors_SM&hash=item566083498e
 
I know many Transformers have 3v output but 1.5 would be rare commercially.

Thanks Sol,
                I think I may have it sorted. I`ve found an old phone charger…..4.5v @ 315 ma. I connected a 1/2 watt 560 ohm resistor in the line and it works !!!.
                Problem solved and thanks for your input.
Cheers Brian

I was gonna say, Gormo, what do you want to drive with it?

But Sol's covered it.

Brian, that will work as long as the load resistance does not change. I assume you have measured the voltage across the load when all connected up?

Bang!

Afraid not Sol !!!
Oh Well…….just wait for that Earth shattering Kar boom !!!
Thanks Sol

Could end up with an extremely hot resistor...

Or just like I have found on my signalling circuits - one got so hot, it burnt out & fortunately went open circuit.

Oh Well..?????…….today it does not work…….so back to the drawing board. The circuit works with the battery but not with the adapter.
I don`t have the electronics knowledge to work it out , so for the moment it can go back into the too hard basket.
We`ll call it day on this one.
Cheers Gormo

Brian, OK so I assume your globes, etc, so if you are certain that it needs 1.25 v and takes 100mA ,  with a 4.5 v supply, you have to drop 3.25 v & with 100mA load, you need a resistance of 32.5 ohms

Ohms Law  R= E/I  so 3.25 divide by 0.1  = 32.5   & the wattage needed is 0.325w so the closest resistor,  from Jaycar is 33 ohms 1 watt code  RR-2538.  Any change to the load requirements & you need to change the resistor.

Sometimes it is better to have a voltage regulator.

Thanks Ron,
                I am more inclined to walk away from it, however next time I`m at JayCar, I`ll get one of those resistors and give it a go……..thanks for your help.
Cheers Brian