transformer mods

[jonastus]

just a little question

I have a ac dc transformer thas is rated 12 vdc

the one you plug direct in the wall its 1 amp

but I read 16 volt dc out of it

question

how can I step it down to 12 vdc

thanks

[anatech]

Hi jonastus,
This voltage will drop quickly under load. IIF your load is light enough, you may be able to get by with a three terminal regulator. There is every possibility that this will not work well as the regulator may "drop out" at the bottoms of the ripple wave form.

The proper way to do this might be with an AC wall mount unit rated at a higher voltage. You can then use more capacitance and better diodes. This will give you more headroom for the regulator.

-Chris

[jonastus]

ok so for a charlize amp for example

the maximum voltage is 13,8 volt

does the voltage will drop enough

or the regulator will be a must

[ocool_15]

whats the current draw for that? If anything has a 13.8V rating I wouldnt put 16V into it, at least from a reliability standpoint.

[Hector Ruiz]

Why don't you simulate the load on the transformer with a dummy resistor to see the "loaded" output voltage. You will need to know the voltage required by your amplifier and the nominal current draw. Apply Ohm's law: (amplifier's required voltage) / (nominal current draw) = dummy load resistance. You will also need to know the power dissipation by Watt's Law: (amplifier's required voltage) x (nominal current draw) = power dissipation. Purchase a resistor and place it across the wall-wart's DC output and measure with a voltmeter. Sure is a lot cheaper than a fried amplifier.