High current voltage regulator using lm7824

tigox

Member
2012-07-10 7:24 pm
Hey there, so in the future i'm building portable speakers with a tda7294 anplifier off ebay, the problem is i'm running this from a battery so i'll need an smps power supply to give me double supply off my battery, so the smps gives out +-35v but the amplifier only takes in 24-0-24 at max, so i was thinking of making a high current voltage regulator.
I've been seeing a lot of circuits like this:
ZENER-REGULATION-386x550.png


the problem is that i also have a negative regulation going on, and it might get unbalenced....
so what i am thinking of doing is instead of the zener i would put an LM7824 to control the base of the base pin of the transistors :D

So i first, will this work??
and second could i use the lm7824 for both the negative and positive transistor's base , or will i need an LM7924 for the negative transistor's base?

Thank you for your time :DD
 
It might be more economical to find an smps that delivers the right voltage. First of all because it will not cheap to build this regulator, if only for the heat sinking you will need. Second, you will waste precious battery power with this scheme, at least half of all your battery capacity, and.probably more.
 

tigox

Member
2012-07-10 7:24 pm
It might be more economical to find an smps that delivers the right voltage. First of all because it will not cheap to build this regulator, if only for the heat sinking you will need. Second, you will waste precious battery power with this scheme, at least half of all your battery capacity, and.probably more.

yeah i though so.... so any other ideas? :S because i for the life of me cant't find an smps with +-24v :(
 
@tigox it is a complete waste to have a SMPS with usually good eff rising the voltage and then have a linear regulator to stabilise the voltage at a needed level, linear regulators wase lots of power on the series pass element, i would never use this combination.

Any SMPS can be modified for lower voltage cus that usually means lower power so a smaller stress on the power elements, if the SMPS is regulated then just by changing the upper resistor on the voltage divider of the feedback network will reduce the voltage at the needed level, if the SMPS is not regulated then you need to modify the power transformer, rewind the secondary coils for the needed voltage.

If you are not sure what to do then post the SMPS schematic here and i will try to guide you trugh it.