7815 and 7915, which type A or C?

[rfenergy]

The 10uF caps are after the big 6800uF filter caps but before the regulators, so maybe they are part of some bypass for the big filter caps.
The design is mur860's into 6800uF the into 10uF caps and the into 7815 and 7915, then out to 10uF, the to 47uF then to op-amp power rails. (btw this is on Behringer Truth B2031 powered monitors,with LM3886 amps)

out,
Robert

[metalsculptor]

Originally Posted by nigelwright7557

The datasheet says you dont need a decoupling capacitor on the output.

Maybe so, but a board full of TTL with a 2 MHz clock and 10 ns rise times is not something I would hang off a slow regulator with no decoupling. The other advantage is the decoupling acts as a low pass filter reducing regulator noise.

[Speedskater]

I wouldn't base a design on spec. sheets that differ in age by maybe 30 years. Test methods change with time. Chip manufacturing processes change with time.

[rfenergy]

Originally Posted by Speedskater

I wouldn't base a design on spec. sheets that differ in age by maybe 30 years. Test methods change with time. Chip manufacturing processes change with time.

Hello,

Is this referring to what I posted?

Thank You,

Robert

[Speedskater]

Originally Posted by rfenergy

Hello,
Is this referring to what I posted?
Thank You,
Robert

Yes, I think that you are putting too much faith in spec. sheets. Manufacturing techniques change with time, mfg. seldom update the spec. sheets.

[rfenergy]

I get what you are saying.

The newer parts are probably an improvement, but the sheets do not reflect this fact.

out,
Robert

[jitter]

Originally Posted by Speedskater

Yes, I think that you are putting too much faith in spec. sheets. Manufacturing techniques change with time, mfg. seldom update the spec. sheets.

I wouldn't be too sure of that. Recently I downloaded some datasheets fom ST and others of some very standard components (78xx, LM317, etc). to answer a question in another thread (My Transistors, original or copy?) and actually found them to be very up to date. All of them had a revision date in 2010.
These were downloaded directly from the manufacturers and not at third party, though...

[rfenergy]

Jitter,

it looks like you are correct, I found new spec sheets at On-Semi. The newer 78XX and 79XX have different specs (and generally better) than some older spec sheets I found on the internet.

The newer 7915 form On-Semi has better specs than the older ones.

I guess the question I still have is the On-Semi NCP7815TG with 6.8uV/VO output noise voltage and 70db of ripple rejection better than the old LM7815A I have in there? The LM7815A is over 10 years old, the newer spec sheet I found on the LM7815A has a better noise spec of 90uV. but I do not know if this is the total noise or if it is measured in uV/VO.

Thank You,
Robert

[jitter]

The units tell you if it's total noise or noise per volt output.
total noise = uV
noise per volt output = uV/VO.
If the manufacturer used the units correctly, that means that 90 uV is total noise.

A bit of mathematics shows this is most likely true:
6.8 uV/VO * 15 VO = 102 uV (total noise for the NCP7815TG)
90 uV/15 VO = 6 uV/VO (noise per volt output for the LM7815A)