Next time I'll do the math with my fingers instead using my head, you are right, your error amplifier input impedances are good.
Why use discrete master current source instead LM317? Becouse constant-current characteristic of LM317 tends to become deteriorated in the high frequency range much more against discrete CCS, but you could use one LM317 as floating preregulator Walt Young superegulator style as it will clean some garbage from mains.
Why use discrete master current source instead LM317? Becouse constant-current characteristic of LM317 tends to become deteriorated in the high frequency range much more against discrete CCS, but you could use one LM317 as floating preregulator Walt Young superegulator style as it will clean some garbage from mains.
Hi,aparatusonitus said:
the fast shunt regulator hides the slowness of the 317 current source.
I think the 317's only disadvantage in the fast shunt context is high voltage drop. That's why I asked for low voltage drop alternatives and why I was so interested in the voltage drop that On's CCS achieves.
Hi,
in sim, using zenys CSS gives an 30dB improvment of high frequency ripple rejection above 100kHz (the graph is acutally more complicated).
With aparatus' CSS I had no improvement, but, since no part values are given, I could have chosen wrong values.
One has to adjust R12 to get the same current, though.
Rüdiger
in sim, using zenys CSS gives an 30dB improvment of high frequency ripple rejection above 100kHz (the graph is acutally more complicated).
With aparatus' CSS I had no improvement, but, since no part values are given, I could have chosen wrong values.
One has to adjust R12 to get the same current, though.
Rüdiger
Uh-oh.
Things are more complicated. The sims tells a tendency of oscillation. And you screw up the high F's regulation with that LED at the output of the CS.
Don't know what's going on.
Rüdiger
EDIT: it's mostly wrong what I#ve written regarding those different CSS. The sim results are supersided by the ESR your provide for the caps...
Things are more complicated. The sims tells a tendency of oscillation. And you screw up the high F's regulation with that LED at the output of the CS.
Don't know what's going on.
Rüdiger
EDIT: it's mostly wrong what I#ve written regarding those different CSS. The sim results are supersided by the ESR your provide for the caps...
I checked the real circuit again at the workbench. It seems, if I use no current source, or current mirror for the diff-pair (j4 in the schematic) I got lower noise. With an active mirror or -source, I can see some noise on the scope at the output of the reg (5mV/div).
And what are your concerns against LEDs? There was a hot debate some years ago here about the noise of leds which led to no consensus (well, not that I know a single issue or thread where consensus had been found...)
Rüdiger
And what are your concerns against LEDs? There was a hot debate some years ago here about the noise of leds which led to no consensus (well, not that I know a single issue or thread where consensus had been found...)
Rüdiger
Noro's patent has all values for parts .
good for analysis
patent 4366432
useful link:
http://www.pat2pdf.org/
good for analysis
patent 4366432
useful link:
http://www.pat2pdf.org/
Thanks Zen Mod, that gives me a few ideas. I don't see, though, were my main CSS has major flaws. I'll try fet/resistor reference in order to achieve lower noise.
By the way, the use of the cfp in the diff-amp lowers Zout by a factor of 20.
@Andrew: with 100mA, the real reg could have a voltage drop of only 1 Volt. I don't think it's optimum in regard of regulation, though
Rüdiger
By the way, the use of the cfp in the diff-amp lowers Zout by a factor of 20.
@Andrew: with 100mA, the real reg could have a voltage drop of only 1 Volt. I don't think it's optimum in regard of regulation, though
Rüdiger
the lowest input voltage (Vimin) - Vdrop = max Vout.Onvinyl said:
If Vdrop goes up then a higher voltage transformer is required.
Go down that route and all the dissipations go even higher when mains voltage is running at maximum.
There is a big advantage in component size and heatsink requirement and internal heat generation by adopting the lowest Vdrop for the CCS. It should not affect the operation of the shunt or the circuit. It's simply down to heat.
Hi Rudiger,
how are things going? Round and round? However, you are going for a nice project this time. Shunt regulators are popular in Germany, right? Well, they offer excellent sonic performance due to low deteriorating level, Class A operation, not much harmful global negative feedback generated effects here...
The active series pass element (instead of resistor), improves ripple rejection, further improvements are possible by using more adequate current sources and voltage references. Even the LTP would deserve and highly appreciate a better CCS for its function. 1KOhm is a very low impedance compared to the achievable several tens of MOhms. Light diodes are noisy having a zener-like behavior.
May I come up with a slightly different version?
Both series and parallel regulators need a lot of internal feedback. FETs are much more accurate for voltage to current conversion than bipolars.
The LTP is heavily simplified.
how are things going? Round and round? However, you are going for a nice project this time. Shunt regulators are popular in Germany, right? Well, they offer excellent sonic performance due to low deteriorating level, Class A operation, not much harmful global negative feedback generated effects here...
The active series pass element (instead of resistor), improves ripple rejection, further improvements are possible by using more adequate current sources and voltage references. Even the LTP would deserve and highly appreciate a better CCS for its function. 1KOhm is a very low impedance compared to the achievable several tens of MOhms. Light diodes are noisy having a zener-like behavior.
May I come up with a slightly different version?
Both series and parallel regulators need a lot of internal feedback. FETs are much more accurate for voltage to current conversion than bipolars.
The LTP is heavily simplified.
Attachments
Hi Lumba,
thanks for this *very* useful contribution!
Your T14, however, does not turn in my simulation, still keeping my upside-down error amp configuration. As I understand it, it should be part of the current mirror (T12, T13) but probably I'm wrong.
Your input CSS looks tricky, I'll chew on this a bit...
thanks,
Rüdiger
thanks for this *very* useful contribution!
Your T14, however, does not turn in my simulation, still keeping my upside-down error amp configuration. As I understand it, it should be part of the current mirror (T12, T13) but probably I'm wrong.
Your input CSS looks tricky, I'll chew on this a bit...
thanks,
Rüdiger
Leaving T14 for now.
I have the problem, that with a current source in the diffpair tail, the error amp does (often) not work, if the output compound pair (Q1, M1) is attached. With resistor in the tail, this is no problem. I first had this problem with the real circuit, but the sim shows the same behaviour with a non-ideal current source.
So I inserted Q8, an E-follower which also helps Zout in the high freq region a lot.
But, since I did not check if it works in reality, and there might stability issues as well, *and* it was an attempt out of pure desparation: why doesn't it work without Q8?
Rüdiger
I have the problem, that with a current source in the diffpair tail, the error amp does (often) not work, if the output compound pair (Q1, M1) is attached. With resistor in the tail, this is no problem. I first had this problem with the real circuit, but the sim shows the same behaviour with a non-ideal current source.
So I inserted Q8, an E-follower which also helps Zout in the high freq region a lot.
But, since I did not check if it works in reality, and there might stability issues as well, *and* it was an attempt out of pure desparation: why doesn't it work without Q8?
Rüdiger
Attachments
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.