Hi,
build the neg. side, this has no probs with the mentioned cap over R2. For some reason, the op177 seems to be fine choice as error amp, and cheap as well.
Iko,
You should be able to calculate Vout = (R2*Vref/R3)+Vref, so you see, even small deviations in the LEDs (=Vref) can lead to quite a bit of difference.
Rüdiger
build the neg. side, this has no probs with the mentioned cap over R2. For some reason, the op177 seems to be fine choice as error amp, and cheap as well.
Iko,
You should be able to calculate Vout = (R2*Vref/R3)+Vref, so you see, even small deviations in the LEDs (=Vref) can lead to quite a bit of difference.
Rüdiger
ikoflexer said:
Well, it's basiclly syn08's design. It will be uesd for my next phonostage study which is far from being finished.
Rüdiger
Q1 and Q2 should have resistors to ground at the emitters to give them basic bias in case of low load current. Otherwise they will glitch on transients because the outputs will be horribly slow and very capacitive, easily saturating the drivers. Furthermore the dramatic reduction in Ft may destabilize the feedback loop and cause oscillation or resonance.
The D4xH11 are huge and slow outputs compared to the loading this reg is designed for. You will get better RF PSRR by using outputs suited to the application, which in this case would be something like the MJE150xx pair from ONSemi.
The D4xH11 are huge and slow outputs compared to the loading this reg is designed for. You will get better RF PSRR by using outputs suited to the application, which in this case would be something like the MJE150xx pair from ONSemi.
yesterday I noticed the big surface mount D2PAK LM317/337, listed as 40V/1.5A devices
are they good ? I dont know, but decided to give them a try
apparetntly the output cap should not have too low ESR
just thought I would mention it since most curcuits I have seen have had bypass film caps etc
and I have never heard about this before
are they good ? I dont know, but decided to give them a try
apparetntly the output cap should not have too low ESR
just thought I would mention it since most curcuits I have seen have had bypass film caps etc
and I have never heard about this before
Tinitus, look at the MC78xx/79xx regulator series from ONSemi. Going by the datasheet they are much improved versions of the LM regulators. They should perform better than the 337/317 except for not going below 5V. You can order samples. I would be very interested in your results with these.
Im going to use TO-92, MC78L12ACPG/MC79L12ACPG for +/-12V
relatively expencive, but they looked better than cheaper ones
maybe they are just 'selected', I dont know
but I also need 30V
and my trafo AC voltage is 2x 0-24-28V
I think the input voltage will be too high for any of the 78xx/79xx
would be easier to buy two new trafos
and probably even cheaper too, and easier
but what would I learn from that
bass guitar preamp
but since such amp curcuits are often 'simple', it ought to be benefitial with good low noise supply 
thats what I read, some time ago
but was told later it is rubbish
now, I expect it could very well be true
my guess is.......
'fixed voltage' types probably benefits from the much simpler ground connection
as said, I would use fixed volatge types
but the adjustable LM317 variant 'appears' to handle higher voltage
thats would be my only reason
and yeah, for whatever strange reason, not sure there would be a 20V type, if thats what you needed
For the LM devices it may be true. But I would treat the MC series as a different animal until I had some direct experience. IIRC according to the datasheet they are better than the LM3x7 and LM78xx/79xx series. I haven't measured them myself because I trust the datasheet, and the datasheet says they're better. I trust that means they should sound better.
Jenyok (and anyone else), I'm interested in what you think about my Kmultipliers. This is a bit more on-topic anyways. I've written a website article about them since I think they deserve some good documentation. I'd appreciate feedback on the article from anyone:
The K Multiplier
Jenyok (and anyone else), I'm interested in what you think about my Kmultipliers. This is a bit more on-topic anyways. I've written a website article about them since I think they deserve some good documentation. I'd appreciate feedback on the article from anyone:
The K Multiplier
Note that OnSemi uses 500mA load current on the MC78XX devices in their data sheet -- Zout is inversely related to load current, when you make this adjustment Zout for the LM317 @15V would appear identical to the MC78XXX.
If you're going to use the LM317/337 avoid the temptation of using more than a few tens of uF on the adjust pin --
If you're going to use the LM317/337 avoid the temptation of using more than a few tens of uF on the adjust pin --
MC type ? and high input voltage 
.....
highest output voltage, 24V, ofcourse
and voila, there it is, MC7824/7924, both 40V types, TO-220, 1A max for the negative, 2A for positive
Kean, you are a great guy
so, now I have might have the negative side of symmetric +/- sorted by using fixed voltage MC types
and for the higher 30V voltage I only need a positive voltage
and thus 'could' use a variable LM317
which I 'suspect' present less problems than the negative one, maybe
sorry if I sound confused, but that I am
..... highest output voltage, 24V, ofcourseand voila, there it is, MC7824/7924, both 40V types, TO-220, 1A max for the negative, 2A for positive
Kean, you are a great guy
so, now I have might have the negative side of symmetric +/- sorted by using fixed voltage MC types
and for the higher 30V voltage I only need a positive voltage
and thus 'could' use a variable LM317
which I 'suspect' present less problems than the negative one, maybe
sorry if I sound confused, but that I am
Jackinnj, maybe you were looking at the Fairchild MC7xxx datasheet. This is the ONSemi version:
http://www.onsemi.com/pub/Collateral/MC7800-D.PDF
http://www.onsemi.com/pub/Collateral/MC7800-D.PDF
tinitus
.
http://www.ti.com/lit/ds/symlink/tps7a3001.pdf
http://www.ti.com/lit/ds/symlink/tps7a4901.pdf
.
See and read those documents.
.
http://www.ti.com/lit/ds/symlink/tps7a3001.pdf
http://www.ti.com/lit/ds/symlink/tps7a4901.pdf
.
See and read those documents.
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