Where to source an autotransformer, tapped coil

[eamonn58]

I am building an alarm circuit and need an autotransformer to step up the voltage powering the pizo sounder. Trouble is I can't find anyone who sells the aurotransforners. Any one know where to get them.

 

[MaxHeadRoom78]

What is the reason for using an Auto-transformer?
What voltages?

 

[eamonn58]

the auto transformer will up the voltage to give more volume to the pizo (the louder the better) it is also smaller than a traditional transformer. and cheaper (if I can find a manufacture) The voltage will be up to 12v from car battery and a backup battery of maybe 9volts.

 

[MaxHeadRoom78]

I don't see why it would be smaller than the isolated version?
The Va would/should be the same?
If this is high frequency, try the pulse transformers from Hammond, DigiKey etc.

 

[Nigel Goodwin]

I am building an alarm circuit and need an autotransformer to step up the voltage powering the pizo sounder. Trouble is I can't find anyone who sells the aurotransforners. Any one know where to get them.

I would imagine they are custom made for the manufacturers who use them, and probably not available 'off the shelf'. As already mentioned, there's little reason for such an auto-transformer to be much smaller or much cheaper - essentially all you save is the length of the primary on the secondary, and if you wire the isolated transformer as an auto-transformer you will get a higher output anyway.

 

[Les Jones]

Why not just buy a sounder that contains the oscillator as well as the transducer ? Most of these devices just need to be supplied with DC (Normally 12 volts,)
This is one example

Les