alternative needed for LM7805 LM7809 LM79M09


Paid Member
2002-09-25 11:01 am

Try a similar circuit to shunt out noise from the 78xx series outputs, if you think it's needed.

Burr-brown has some REG series regulators that are fairly low noise and very low-drop, and so do Linear.

But you will require to build them up from the ground, the circuitry may be slightly different (the REG series are SO8, for example).

I'm not sure of any drop-in replacement for the 78xx series which will result in lower noise...
For a soundcard you are going to be working with surface mount components -- Linear introduced the LM3080 a few months ago -- this is a low noise, low dropout regulator which uses a single resistor and should certainly beat the LM7809 in the relevant terms. It is available in MSOP, SO223 and TO220, no such equivalent for the negative rail, however. They are available in samples from Linear, or from DK for ~ $2.50.

Check Linear's product tables -- I have been very pleased with their low noise regulators, but the best seem to be surface mount, like the LT1761, LT1964

And Sangram's citation of the Wenzel Associates article is a must read -- this knocks the noise down to the nanovolts.

my biggest problem is currently space is limited due the
currently big size of the soundcard already.

heres a picture of it (just put in those nichicons some hours before):


heres the schem of the dac :


pircture of the original card :


i am thinking about what to do next and if the change of the LM´s would be audible ?