Pak budi.
Saya sudah aplikasikan yang sulzer dan hasilnya memang tidak bohong padahal
saya hanya memakai ne5332......gantungan kuncinya p'paul hehehe.
Salam...iwans
Budi H Roesdiharjo wrote:
> Katanya baik untuk power supply DAC-NOS.
> Experienced audio DIYers are familiar with monolithic linear
> regulators like the 78xx series and the LM317. Here’s a simplified block
> diagram
> of a standard linear regulator, from National Semiconductor’ s Application
> Note 1148 :
> Let’s see... We have an op-amp, a couple of transistors, a voltage
> reference, and a few resistors. Can we build a linear regulator from these
> individual components? Yes, we can!
> Why DIY a Regulator?
> Before monolithic IC regulators became popular, people made linear
> regulators from discrete components and maybe a general-purpose IC or two.
> I’ll
> call them DIY regulators, lacking a better term.
> Like the μA741 IC op-amp did to small discrete amplifiers in the
> late 1960’s, the invention of the 3-terminal fixed IC regulator a few years
> later started pushing out DIY regulators and fully discrete regulators. These
> IC
> regulators are easy to apply, take up little board space, and have quite good
> performance. The secondary effects of these facts are that 3-terminal
> regulators
> like the LM317 are made by several manufacturers, and you can get them for as
> little as about 50 cents in single quantities. And if you want to spend a
> little
> bit of money to get even better performance, there are many improved
> regulators
> on the market. So why would one want to return to the days where people made
> their own linear regulators from generic parts?
> The main problem with the improved IC linear regulators on the
> market is that they have nonstandard pinouts and they can be fairly
> expensive.
> Consider the Linear Technology LT1581 high-current high-speed LDO regulator:
> it’s a 7-pin TO-220 type package and it costs about $13 for single units. For
> $13, you can buy a pretty good collection of parts. If you can afford the
> board
> space the DIY approach takes up, you can often equal or better the
> performance
> of monolithic IC regulators.
> This article follows the history of a popular series of DIY linear
> regulators. Starting from initial concepts basically idential to the
> archetype
> block diagram above, this particular thread through history will wind up in a
> very sophisticated design. Because this final design developed piecemeal over
> the course of two decades, that’s how I'll show it. I think showing the steps
> this series of designs went through aids understanding of the final
> design.
> We will follow the thread through the pages of the journal The
> Audio Amateur , the forerunner of audioXpress . audioXpress offers a complete
> catalog of back issues going back to 1970, so that’s how I followed the
> history. (Most
> of the back issues are still available in printed form; a few years in the
> 1970s
> are sold out now and are only available on
> their 1970's reprint CD .) My purpose here is not to duplicate this material,
> but to
> summarize it and serve as a guide to it. If you want the full details of
> these
> designs, I recommend that you get the issues I reference. Many of these
> articles
> have a lot of information in them that I am glossing over
> here.
> How Does a Series Linear Regulator
> Work?
> The archetype block diagram above is called a series linear
> regulator, because the pass transistor is in series between the input and
> output. This type of regulator is based on a simple idea: you can control the
> voltage at the output leg of the transistor by manipulating the voltage at
> the
> base. Let’s study the archetype design above.
> Connected
> to one input of the op-amp (called the error amp) is the voltage reference,
> V REF .
> You can make voltage references in many different ways, so the technology
> used
> isn’t important at this point. A good reference puts out a fixed voltage
> under
> varying conditions, and you can get versions that put out any of several
> standard voltages.
> Connected to the other input of the error amp is the midpoint of a
> voltage divider. We’ll come back to this later.
> An op-amp tries to make its two input voltages equal by adjusting
> its output voltage. In the diagram, the output of the error amp is connected
> to
> the base of an NPN transistor: when the error amp drives current into this
> transistor’s base, it allows current to flow from collector to emitter, and
> that
> transistor in turn pulls current from the base of the pass transistor. This
> arrangement lets an op-amp capable of driving a few tens of milliamps control
> an
> amp or so of current across the pass transistor.
> Now
> comes the neat bit. Let’s say you have a 5V reference and the voltage divider
> is
> set up to divide the voltage from V OUT
> to GND by 4. Since the op-amp tries to make its two inputs equal and one
> input
> (the voltage reference) stays constant, it will adjust its output voltage
> until
> 5V appears at the midpoint of the divider. Since it’s a divide-by-4 voltage
> divider, V OUT
> goes to 20V and it stays there because it’s a real-time system, constantly
> adjusting to changing conditions.
> Voilá, you have a series linear
> regulator.
> (If you want to read more about the operation of linear
> regulators, I recommend reading the AN-1148 app note I reference
> above.)
> Now, this simple design isn’t perfect. The error amp can only slew
> so fast, the voltage reference will have some error, the output of the
> regulator
> has an effective impedance resulting in current-modulated voltage drops, and
> all
> of the components in question will drift to some extent as the temperature
> changes. Furthermore, all of the components in the regulator generate some
> noise, and this gets worse as temperature rises.
> Sophistication Begins: The Sulzer
> Regulator
> In the 2/1980 issue of The Audio Amateur Mike Sulzer
> published this regulator design:
> There are several subtle improvements in this design relative to
> the archetype:
> It uses the fast, low-noise NE5534 as the error amp.
> The unregulated supply voltage ripple is largely filtered by a
> RC low-pass filter with a low corner frequency (R3 and C3+C4), and the
> zener
> noise is mitigated by another filter, R4 and C5. These filters are a step
> beyond the bypass caps you find used on monolithic linear regulators,
> because they’re so tightly woven into this design.
> The large C1 cap rolls off the gain of the regulator starting
> at a low frequency so that high frequency noise isn’t amplified by the
> error
> amp.
> Output
> voltage is V REF
> × (R2/R1 + 1).
> The NE5534 was the hot new chip back in 1980, priced at about $11
> in 2003 money. Now the NE5534 is generic, and you can can get them for under
> $1.
> The cost of the op-amp pretty much exchanges evenly with the cost of an
> LM317.
> The parts above and beyond what you’d add to an LM317 circuit (say, 3 caps
> and 2
> resistors) should only cost a few dollars more, and the performance should be
> better than you get with an LM317. I'm reliably informed that the error amp
> within an LM317 is closest in performance to a 741; as the error amp’s
> performance goes, so goes the regulato’s performance. Some look back on the
> NE5534 with disdain these days, but it’s still miles ahead of the
> 741.
> There’s a lot of good information in the article about how Sulzer
> designed and tested his regulator, so it’s worthwhile to dig this one up if
> you
> plan on making Sulzer regulators.
> Sulzer Variations
> In the 1/1981 issue of The Audio Amateur , Sulzer published
> a follow-up article. This article feels more like a collection of random
> ideas
> thrown out for people to try, rather than another strong design like the
> first
> article. Since there are later variants that perform better and are no more
> complex, I won’t show a schematic for the '81
> circuit.
> The following ideas first appeared in the 1981
> article:
> using an LM317 as a pre-regulator
> replacing the zener with a precision voltage reference
> connecting the pass transistor’s collector directly to the
> unregulated supply
> adding another, bigger transistor on the output in Darlington
> configuration to get more output current
> The most notable of these advances is the pre-regulator. It keeps
> the voltage drop across the pass transistor more nearly constant, improving
> its
> performance. It also removes the need for the low-pass filter on the V+ pin
> of
> the error amp, which saves on parts and probably improves the op-amp’s
> performance since it reduces its supply impedance.
> In the 1980 article, Sulzer credits Jim Breakall (among others)
> with helping with the design of the regulator. In the 1/1983 issue of The
> Audio Amateur Breakall and others published an article with an extensive
> series of tests of what is basically Sulzer '81. They focused on output
> impedance, and they compared the new DIY design with the LM317 and LM340.
> They
> also tested a few different op-amps in the regulator. As one might guess, the
> Sulzer regulator with a 741 in it performed about the same as an LM317, but
> with
> a good op-amp the Sulzer regulator greatly surpassed the LM317. They did show
> a
> small amount of improvement from adding the pre-regulator, but not as much as
> you might think. This article is worth digging up for the test results and
> methods.
> In the 1/1987 issue of The Audio Amateur , Jan Didden chimes
> in with some variations on the Sulzer regulator. He uses a 7818 as a
> pre-regulator and a 7805 as a reference, and he uses a better pass transistor
> than the generic one Sulzer used. It’s an interesting circuit, but I don’t
> think
> it’s worth showing here.
> Sulzer-Borbely Regulator
> Also in the 1/1987 issue, prolific designer Erno Borbely published
> a moving coil preamp with a Sulzer type regulated power supply. Borbely
> didn’t
> go into any details about his variations, probably because it really isn’t a
> major improvement. The Borbely variant is simply a thoughtful pick-and-choose
> exercise from the ideas that went before. It’s a solid design worth
> repeating:
> As you can see, it uses an LM317 pre-regulator, but it’s more
> thoughtfully implemented than in the Sulzer and Breakall
> articles.
> The only quibble I have with the Borbely design is the choice of
> the LM336 band-gap reference. The main thing about band-gaps is that they can
> be
> made with much lower voltage drops than zeners, but they are noisier than a
> buried zener type reference. Since we don’t need the low voltage feature for
> high-quality audio, I think it’s more sensible to go with an LM329 buried
> zener
> here. Nevertheless, a band-gap reference is still an improvement over a
> standard
> zener both in terms of noise and stability. It’s just that a buried zener is
> even better, if you can afford the higher voltage
> drop.
> Jung Super Regulator
> Finally we come to the Jung regulator. In the first two issues of
> TAA in 1995, Jung describes his circuit and gives some very detailed test
> results of it vs. several other linear regulator types. In issue 3, Jan
> Didden
> gives a PCB layout for the circuit and gives some advice for applying the
> regulator circuit. And in issue 4, Gary Galo does some subjective tests on
> the
> regulator dropped in as mods to real circuits, with side-bars written by Jung
> and Didden. If you only want to pick up a few back issues of all the ones I
> mention, pick up the first two in this series at minimum. The full set of
> four
> is very helpful.
> The major differences in the Jung regulator relative to the
> original Sulzer design are: better pass transistor (D44H11), different drive
> scheme for pass transistor, no pre-regulator, better op-amp (AD797), op-amp
> protection, precision reference (LM329), and remote
> sensing.
> The error amp in the Sulzer regulator effects voltage regulation
> in a standard way: it varies its output current which changes the voltage
> drop
> across the pass transistor. The Jung regulator uses a much different control
> mechanism. In the Jung regulator, a constant current source (Q2 and assocated
> parts) pushes current to the base of the transistor, and the error amp sinks
> as
> much of this away as is required to maintain the desired output voltage. (The
> diode inline with the op-amp’s output is why it can only sink current.) As I
> see
> it, the primary advantage of this configuration is that the CCS indirectly
> limits the maximum output current of the regulator to a reasonable value. A
> short across the output of a stock Sulzer regulator would probably destroy
> the
> pass transistor.
> There is a low-pass filter on the op-amp’s V+ pin as in the
> original Sulzer design (R3, C2), but Jung says this is optional. One gets the
> impression that he’d rather just depend on the power supply ripple rejection
> behavior of the op-amp. There’s some worry that the resistor in this filter
> could have load-modulated voltage drops across it, thus possibly
> increasing the ripple at the supply pins. In the fourth article in the
> series, Gary Galo says he heard a difference between a version with the
> filter
> and without, and says he prefers the version with the
> filter.
> Notice that the pass transistor’s collector connects directly to
> the unregulated supply input, not after the low-pass filter like in the
> original
> Sulzer circuit. This keeps the high-current path low in impedance and lowers
> the
> influence of the output current on the op-amp’s power
> rails.
> The diodes on the error amp’s inputs protect it from overvoltages.
> Some op-amps have diodes across the inputs like this already, but even a
> small
> discrete diode can pass far more current than the on-chip
> diodes.
> There are a few layout considerations pointed out in this series.
> They aren’t part of the circuit design per se , but they are part of the
> intended implementation. (You could do both of these to the Sulzer variants
> as
> well.) First, R2 and R8 do not connect directly to the output of the pass
> transistor as drawn. Instead, just connect them together and put a wire pad
> between them. Second, I used two different ground symbols in the schematic;
> each
> one is a separate star ground. The two wires from the pass transistor’s
> output
> and the R2/R8 junction go to the positive side of the load. This allows the
> error sense circuit to see all errors that happen between the output of the
> regulator proper and the load. A separate wire from each star ground
> centerpoint
> goes to the negative side of the load, so the noise bypassed to ground from
> the
> control and sense circuits only mix at the load/sense point, so the error amp
> can control these errors as well.
> If you do run separate wires from the control and sense grounds to
> the load, you should also connect the ground of the unregulated section of
> the
> power supply to the negative side of the load to avoid a ground loop. Also,
> beware that there is a risk to remote sensing: it greatly increases the size
> of
> the error amp’s feedback loop, and it adds significant inductance and
> probably
> also capacitance from the long wires into this loop. If you add remote
> sensing,
> you must test the power supply for oscillations, especially if you use the
> fast
> op-amps that Jung recommends. The fourth article in the series has info on
> troubleshooting oscillations.
> Jung 2000 Regulator
> In the 4/2000 issue of Audio Electronics (successor to TAA), Walt
> Jung published a new version of his regulator with several improvements over
> the
> 1995 circuit:
> I've used the same component names as far as possible to aid
> comparison to the 1995 circuit. I reuse the C2 designation because it’s
> actually
> the same capacitor on the modified Didden boards, though it has a new role in
> this circuit. In all other cases, new components have new
> names.
> The first thing you notice is the LM317 pre-regulator, but I’ll
> talk about that later. Pretend for the moment that the input comes from just
> before D1.
> Far more important is the change to the error amp’s power
> connection. Notice that V+ comes from the output of the power supply. The
> error amp runs from the regulator’s clean output power instead of
> lightly-filtered unregulated power. Obviously R3 and C2 are no longer needed
> with this configuration. C3 also had to be removed because you can’t use a
> film
> bypass cap on the error amp’s V+ supply any more because the amp becomes
> unstable if the output cap’s impedance is too low.
> The diode on the error amp’s output is now a 6.8V zener. This
> helps the regulator start up more reliably. It may be needed in difficult
> situations in the original Jung circuit, but Jung says it’s absolutely
> essential
> in this new circuit. If you were to use a regular diode, the the error amp’s
> output is likely to lock up near the negative rail on
> startup.
> The circuit now uses the AD825. Jung says the AD797 had problems
> in environments with strong RFI, since its sensitive inputs would rectify the
> interference and make the output of the error amp unstable. FET input chips
> are
> less sensitive to this problem. Emitter-degenerated bipolar input chips are
> also
> said to be workable; Jung recommends the AD817. You still want a fairly fast
> chip for this purpose, and a strong output stage
> helps.
> The
> current source’s default value has been lowered. The D44H11's minimum
> h FE
> is 60, so the minimum current from this configuration is about 330mA. If you
> mirror this circuit for a negative regulator, the complementary D45H11's
> minimum
> h FE
> is 40, so the minimum current would be more like 225mA. You don’t want to
> increase the circuit’s output level needlessly because that puts an
> unnecessary
> load on the output stage of the error amp.
> The LED and its series resistor have been changed to match
> recommendations by Gary Galo in part 4 of the 1995 series. Galo said these
> lower
> the dropout voltage. Jung does mention using the 2N2907 instead of the
> 2N5087,
> but he doesn’t mention dropout, though Galo said this helped as
> well.
> And now for that LM317 pre-regulator. Jung’s implementation is
> infinitely more clever than the pre-regulators used by Sulzer and Borbely.
> Because the LM317 is a floating design, Jung is able to wrap the regulator
> around the pass transistor so that the output of the preregulator always
> stays a
> fixed amount above the output of the pass transistor. The resistor values
> shown
> give a 2.3V drop across the preregulator, which should be high enough that
> you
> can pull 1.5A from it without hitting dropout. The preregulator reduces the
> amount of ripple the error amp has to remove, it reduces small errors through
> the current source, and it takes some of the power dissipation load off the
> pass
> transistor. The only downside to the preregulator is that the dropout voltage
> of
> the combined regulator rises to something on the order of
> 5V.
> The article describes the changes as mods to the Didden circuit
> boards, so I suspect the boards distributed by audioXpress are still the
> original design.
> Schematics
> The schematics above are available as a PDF (36K) which will be easier to
> read than the graphics
> above.
> Final Comments
> Walt Jung has copies of many of the articles he’s written on
> his
> web site . He’s collected the ones relevant to this article’s topic
> here . (Note in particular that he published two intermediate circuits
> between the 1995 series and the 2000 culmination. ) As you can see, Mr Jung
> has
> been thinking about this since at least 1974, in which he gives essentially
> the
> same circuit as the archetype at the top of this article. Nevertheless, I
> think
> the 1980 Sulzer circuit really kicked off a new direction in DIY regulator
> design by concerning itself with cleaning up the error amplifier’s input
> power.
> Budi H Roesdihardjo Poca Jaringan Solusi
> PT.
>
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