Elso, you can improve your 431 regulator. Let R5 be connected to the output. Then you will get a precision voltage. I have used it often when I have wanted a precision 5.00 V reference AND supply voltage (microcontroller with ADC).
A "tripleton" isn't neccessary, a Darlington will do if you have feedback from output.
A "tripleton" isn't neccessary, a Darlington will do if you have feedback from output.
Elso, i didn't read too carefully but why didn't you use global feedback? 431 is a very reliable and stable chip. It has never failed for me, never got broken. I have used around 50000 and they simply work! Not all of them are in the "power" configuration but rather many.
The big advantage is the surprisingly dynamic impedance. Good for surpressing incoming noise.
The big advantage is the surprisingly dynamic impedance. Good for surpressing incoming noise.
Improvements
Hi peranders,
If you read my post carefully you will notice I tried your suggestion already. In fact this was one of the first things I tried. We don't need a "precision" 5 V for the TDA1543. It also works on 8V. 5.08 V is accurate enough. I choose to make a non-feedback circuit to avoid oscillation and HF garbage from the TDA1543 entering the regulator circuit as much as possible. Triple Darlington or simple two transistor Darlington is not a big difference though. That's why I stopped at three. Did you know Audionote has five transistors Darlington connected in the Audionote DAC3 supply?. Thanks again Jean-Paul for a copy of the schematic!
😉
Hi peranders,
If you read my post carefully you will notice I tried your suggestion already. In fact this was one of the first things I tried. We don't need a "precision" 5 V for the TDA1543. It also works on 8V. 5.08 V is accurate enough. I choose to make a non-feedback circuit to avoid oscillation and HF garbage from the TDA1543 entering the regulator circuit as much as possible. Triple Darlington or simple two transistor Darlington is not a big difference though. That's why I stopped at three. Did you know Audionote has five transistors Darlington connected in the Audionote DAC3 supply?. Thanks again Jean-Paul for a copy of the schematic!
😉
Re: Improvements
I used this circuit mainly to reduce cost in my MCU application. 431 is very worth the price. I don't know if there is any better reference?
431 can oscillate accordning to the datasheet but my experience is that the chip isn't so sensitive in real life. It can take much RF-emission too. I have had very good experience with CE testing. Never been to a trouble.
Elso Kwak said:
I used this circuit mainly to reduce cost in my MCU application. 431 is very worth the price. I don't know if there is any better reference?
431 can oscillate accordning to the datasheet but my experience is that the chip isn't so sensitive in real life. It can take much RF-emission too. I have had very good experience with CE testing. Never been to a trouble.
Improvements
Hi Peranders,
I was more worried about emittor follower oscillations than the TL431 as the latter is in its stable region.😎
Hi Peranders,
I was more worried about emittor follower oscillations than the TL431 as the latter is in its stable region.😎
Re: Improvements
Can this really be good?
Leakage from the first approx. 50 nA x 300 x 300 x 300 x 300 = 405 A
Hfe 50 => 300 mA
Leakage 10 nA, Hfe 100 => 1 A
Isn't this a VERY sensitive circuit? Very small leakage generates VERY much current which you don't can control.
Am I wrong?
Elso Kwak said:
Can this really be good?
Leakage from the first approx. 50 nA x 300 x 300 x 300 x 300 = 405 A
Hfe 50 => 300 mA
Leakage 10 nA, Hfe 100 => 1 A
Isn't this a VERY sensitive circuit? Very small leakage generates VERY much current which you don't can control.
Am I wrong?
Am I wrong?
Probably you are probably wrong............ I have no idea what you are talking about from your collection of numbers without a clue as to what they are supposed to represent.
Leakage of what?
50 nA x 300 x 300 x 300 x 300 = 405 A!!!????
Thanks again for your insightful input to the forum.
BTW When using a darligton follower load each follower with a resistor to ground to set a quiesent current for each follower stage. This is neccesary to get a decent Hfe out of each follower stage and will also make each stage operate Class A.
Probably you are probably wrong............ I have no idea what you are talking about from your collection of numbers without a clue as to what they are supposed to represent.
Leakage of what?
50 nA x 300 x 300 x 300 x 300 = 405 A!!!????
Thanks again for your insightful input to the forum.
BTW When using a darligton follower load each follower with a resistor to ground to set a quiesent current for each follower stage. This is neccesary to get a decent Hfe out of each follower stage and will also make each stage operate Class A.
Leakage?
Hi peranders,
I don't know where you got these leakage numbers from and it may escaped your attention but my circuit is a <B>working</B> one!
Audionote uses 680 Ohm resistors from bases to ground in the last four transistors as also Guido Tent does. I just edited in Guido is using 470 Ohm. I will not post the Audionote schematic but Guido's is very similar and can be found here:
http://members.chello.nl/~m.heijligers/DAChtml/suplv.pdf 😎
Hi Fred,
I considered fitting these resistors too as you suggested but as the circuit worked quite satisfactory I stopped adding parts. Remember the "partsfarm"?😉 😉
Hi peranders,
I don't know where you got these leakage numbers from and it may escaped your attention but my circuit is a <B>working</B> one!
Audionote uses 680 Ohm resistors from bases to ground in the last four transistors as also Guido Tent does. I just edited in Guido is using 470 Ohm. I will not post the Audionote schematic but Guido's is very similar and can be found here:
http://members.chello.nl/~m.heijligers/DAChtml/suplv.pdf 😎
Hi Fred,
I considered fitting these resistors too as you suggested but as the circuit worked quite satisfactory I stopped adding parts. Remember the "partsfarm"?😉 😉
Improvement?
Hi Fred,
I just tried it with 680 Ohm resistors from the bases of the Q2 & Q3 to ground. Outputvoltage is slightly lower: 4.75 V but sound is the same. Sonically no improvement. Thanks anyway, Fred.😉
Hi Fred,
I just tried it with 680 Ohm resistors from the bases of the Q2 & Q3 to ground. Outputvoltage is slightly lower: 4.75 V but sound is the same. Sonically no improvement. Thanks anyway, Fred.😉
Re: Am I wrong?
Fred, you know about leakage current in transistors?
I wonder of the benefits of a "quadrupleton".
Besides, Fred, can't _you_ come with some insightful input instead of just complaining?
Fred Dieckmann said:
Fred, you know about leakage current in transistors?
I wonder of the benefits of a "quadrupleton".
Besides, Fred, can't _you_ come with some insightful input instead of just complaining?
Re: Re: Improvements
I think you mean that we cannot ignore recombination and surface leakage for the first one or two transistors, but
your calculations are wrong, since you do not take all effects of
this into consideration. As you might remember from your
semiconductor-physics books, and as can also be seen in the
datasheets for most BJTs, we have a beta-droop not only for
high IC values, but also for low values. Hence, you cannot use
the same hfe figures for all transistors. The first ones will have
a very low Vbe and also a very low hfe.
peranders said:
I think you mean that we cannot ignore recombination and surface leakage for the first one or two transistors, but
your calculations are wrong, since you do not take all effects of
this into consideration. As you might remember from your
semiconductor-physics books, and as can also be seen in the
datasheets for most BJTs, we have a beta-droop not only for
high IC values, but also for low values. Hence, you cannot use
the same hfe figures for all transistors. The first ones will have
a very low Vbe and also a very low hfe.
Re: Leakage?
I look at BC546 datasheet: Collector cutoff current: 15 nA, worst case at 150 deg C 5 µA.
Do you mean four emitter followers connected in chain, with load down to ground from each one of them? If, so that's better.
A "real" quadrupleton has a huge current gain if not measures are taken.
Elso Kwak said:
I look at BC546 datasheet: Collector cutoff current: 15 nA, worst case at 150 deg C 5 µA.
Do you mean four emitter followers connected in chain, with load down to ground from each one of them? If, so that's better.
A "real" quadrupleton has a huge current gain if not measures are taken.
Re: Re: Re: Improvements
Still, some transistors have substantial Hfe at low currents.
This was interesting though, I might test what happens with a quadrupleton.
Christer said:
Still, some transistors have substantial Hfe at low currents.
This was interesting though, I might test what happens with a quadrupleton.
Elso
I don't doubt your subjective sonic results for one second, after all, if it sounds good, it is good.
But any theory as to why the Jung type reg's sound 'hopeless' in this application.
I mean, DC is DC, closer to DC is a better PSU, does the chip somehow thrive on imperfect supply rails?
Line rejection of a bootstrapped Jung reg. is almost immeasurable without great care in measurement technique, so I don't feel that's the issue. Output impedance and noise will all be lower with the Jung reg too.
Any thoughts?
Andy.
I don't doubt your subjective sonic results for one second, after all, if it sounds good, it is good.
But any theory as to why the Jung type reg's sound 'hopeless' in this application.
I mean, DC is DC, closer to DC is a better PSU, does the chip somehow thrive on imperfect supply rails?
Line rejection of a bootstrapped Jung reg. is almost immeasurable without great care in measurement technique, so I don't feel that's the issue. Output impedance and noise will all be lower with the Jung reg too.
Any thoughts?
Andy.
Re: Elso
I am not sure but I suspect the TDA1543 is spitting HF-garbage back into the powersupply. And second with all these clocks running in the same enclosure, Latch, Bitclock, etc. these might couple into the powersuply too, upsetting the regulator.
😉
Hi Andy,ALW said:
I am not sure but I suspect the TDA1543 is spitting HF-garbage back into the powersupply. And second with all these clocks running in the same enclosure, Latch, Bitclock, etc. these might couple into the powersuply too, upsetting the regulator.
😉
Re: Re: Leakage?
May I quote from the Low-Noise Electronic Design book for the one transistor capacity multiplier:
<B><I>"The capacity multiplier circuit has the potential for increasing the filtering time constant by a value equal to the transistor Beta. This conclusion follows because the filtering takes place in the base current, whereas the load current is the transistor emittor current and Ie= BetaxIb. The presence of ripple at the collector of Q1 has little effect since Ie is essentially independent of that voltage " </B></I>
and<B><I>
"If lower ripple is needed, a second transistor can be added as in fig.11-5. This can reduce the ripple by another factor of Beta. It is possible to use the extra transistor as a trade-off for a smaller capacitor. It may be less expensive to buy the second transistor than a large electrolytic capacitor. This two-transistor circuit is also useful when the supply must deliver a large load current. Transistor Q1 handles the current and Q2 provides the gain. When Q1 is a low-Beta powertransistor, Q2 can be selected to increase the current gain".</B></I>
😎
You see peranders gain is just what we want.😎
Hi peranders,peranders said:
May I quote from the Low-Noise Electronic Design book for the one transistor capacity multiplier:
<B><I>"The capacity multiplier circuit has the potential for increasing the filtering time constant by a value equal to the transistor Beta. This conclusion follows because the filtering takes place in the base current, whereas the load current is the transistor emittor current and Ie= BetaxIb. The presence of ripple at the collector of Q1 has little effect since Ie is essentially independent of that voltage " </B></I>
and<B><I>
"If lower ripple is needed, a second transistor can be added as in fig.11-5. This can reduce the ripple by another factor of Beta. It is possible to use the extra transistor as a trade-off for a smaller capacitor. It may be less expensive to buy the second transistor than a large electrolytic capacitor. This two-transistor circuit is also useful when the supply must deliver a large load current. Transistor Q1 handles the current and Q2 provides the gain. When Q1 is a low-Beta powertransistor, Q2 can be selected to increase the current gain".</B></I>
😎
You see peranders gain is just what we want.😎
Re: Regulators for DAC chips
http://db.audioasylum.com/cgi/m.pl?forum=tweaks&n=36904&highlight=elso+tda1541&r=&session=
😎 😉
Hi Andy see also;ALW said:
http://db.audioasylum.com/cgi/m.pl?forum=tweaks&n=36904&highlight=elso+tda1541&r=&session=
😎 😉
Re: Re: Re: Leakage?
But are your circuit really a capacity (capacitance) multiplier???
Elso Kwak said:
But are your circuit really a capacity (capacitance) multiplier???
Elso
The only way I could see this being a problem (assuming a stable regulator) would be non-ideal power or earthing connections, the current flows in which could upset other items / the DAC. An unstable reg. obviously needs rectifying rather than blaming.
That layout issues can certainly be a problem when modifying items, but when designing from scratch you have control, one should never overlook (I'm sure you don't) the importance of layout, the PCB is part of the circuit. it's characteristics rarely shown on the schematic 😉
Interesting stuff anyway,
Andy.
The only way I could see this being a problem (assuming a stable regulator) would be non-ideal power or earthing connections, the current flows in which could upset other items / the DAC. An unstable reg. obviously needs rectifying rather than blaming.
That layout issues can certainly be a problem when modifying items, but when designing from scratch you have control, one should never overlook (I'm sure you don't) the importance of layout, the PCB is part of the circuit. it's characteristics rarely shown on the schematic 😉
Interesting stuff anyway,
Andy.
Re: Re: Re: Re: Leakage?
WIIILMAAAAAAAAAAAAAAAAAAAAAAAAAA!!!!!!!!!!!!!!!!!! </B>
Wilma (in her well controlled and friendly voice): "What is the matter Fred?"
Fred:<B> "*&#$%^
@!&%#
" </B>
In other words, Peranders Give It up or Let Me Go.
Bonnie Raitt, my sweetheart, thanks for the line.
Sorry Fred Dieckmann this is not meant to be you but Fred from the comic TV cartoon "The Flintstones"😀 😀 😀
Peranders,<B>peranders said:
WIIILMAAAAAAAAAAAAAAAAAAAAAAAAAA!!!!!!!!!!!!!!!!!! </B>
Wilma (in her well controlled and friendly voice): "What is the matter Fred?"
Fred:<B> "*&#$%^
@!&%#" </B>In other words, Peranders Give It up or Let Me Go.
Bonnie Raitt, my sweetheart, thanks for the line.
Sorry Fred Dieckmann this is not meant to be you but Fred from the comic TV cartoon "The Flintstones"😀 😀 😀
- Status
- Not open for further replies.