Re: PSUD3 Windows Beta / Preview edition
Duncan,
?
I'm a programmer with 40 years of experience in FORTRAN, C, C++ and Python. ?I've been been doing DSP lately but I've done some GUI development in the past. ?I'm generally known to be excellent at getting a bead on other people's code and an excellent debugger.
?
Is there anything I can do to help with the development of PSUD3?
?
Cheers,
John
|
Re: Anode series resistor
Thank you so much!??
?
Pierre
|
Re: Anode series resistor
I think PSUD assumes the full load is there at
startup unless you set a delay. Normally, the cold valve does not
conduct for a few seconds. The anode resistors are calculated for
full voltage and current, so the transformer winding is normally
enough on its own. If a cathode follower is involved and you are
using NOS valves, watch the cathode-heater voltage. The modern
6922 equivalents have a much higher rating.?
Richard
On 24/09/2024 08:48, Duncan Munro
wrote:
toggle quoted message
Show quoted text
Hi Pierre,
?
PSUD2 should be able to deal with this for you. If you
measure the leg of the transformer at 70 ohms, simply add the
required resistor value (100 ohms) to give your secondary of 170
ohms.
?
Double click on the transformer icon to access the
transformer properties box:
?
?
The press the [...] button shown by the arrow. This will
bring up the Source Impedance Calculator:
?
?
Enter your off load voltage on one leg and the winding
resistance, again for one leg. In reality, you may find the two
secondary legs have a different resistance so just average two.
Note that I've used 170 which is 70 plus the 100 extra. PSUD (in
this example) calculates the source impedance as 230.6 ohms,
however it is taking the effect of the primary into account too.
?
Click OK and it will feed the transformer parameters back to
PSUD2 and you're good to go.
?
Having a small input cap on CLC filters is OK, it helps to
increase the conduction angle and reduce the peak current in the
rectifier. Hope this is helpful.
?
Regards,
Duncan
?
|
Re: Anode series resistor
Hi Pierre,
?
PSUD2 should be able to deal with this for you. If you measure the leg of the transformer at 70 ohms, simply add the required resistor value (100 ohms) to give your secondary of 170 ohms.
?
Double click on the transformer icon to access the transformer properties box:
?
?
The press the [...] button shown by the arrow. This will bring up the Source Impedance Calculator:
?
?
Enter your off load voltage on one leg and the winding resistance, again for one leg. In reality, you may find the two secondary legs have a different resistance so just average two. Note that I've used 170 which is 70 plus the 100 extra. PSUD (in this example) calculates the source impedance as 230.6 ohms, however it is taking the effect of the primary into account too.
?
Click OK and it will feed the transformer parameters back to PSUD2 and you're good to go.
?
Having a small input cap on CLC filters is OK, it helps to increase the conduction angle and reduce the peak current in the rectifier. Hope this is helpful.
?
Regards,
Duncan
?
|
Dear Members
I am trying to design a PSU for a simple ECC88 line stage with a broken PSU. The original one has SS rectification but I'd like to rebuild it completely using EZ81 followed by CLCLC filtering. The reason for the EZ81 is that I have a lot of them! I used the super-cool PSUD2 software but I have some problems because it says that the input current at start is too much. I need to feed a 40mA load at B+ = 250V?
The max input cap suggested for the EZ81 is 50uF so I played around with values like 30uF and 25uF but the PSUD2 still says that there are problems. I should keepp the first cap down to 10-15uF to solve the problem... but I've never seen such a small input cap in a CLCLC filter.??
Now, searching the web I found people saying that with the EZ81 it is important to reach the series resistance stated in the datasheet. My transformer has a secondary rated at 70 Ohms so probably I need something around 100 Ohm. This resistor should go between the secondary and the EZ81's anode, but it seems it is not possible to add it on PSDU2. I am almost sure that this is the same setting? 170 Ohm in the secondary in PSUD2, am I?right?
The other thing is about experiences with the EZ81. If somebody worked with this tube and he's willing to share some experiences, it would be great to get any suggestion!
Regards Pierre?
|
Re: Modelling Dual-Output-Voltage supplies
Correction, the final paragraph should read as follows:
?
Typically the bridge voltage is about 2x the full-wave voltage.
|
Modelling Dual-Output-Voltage supplies
Can PSUD2 model the "dual voltage" circuit?
?
This is where the topology looks like a bridge circuit with four diodes, but you also tap the circuit to get a second output as a full-wave voltage.
?
Typically the bridge voltage is about 2x the bridge voltage.
?
Thanks.
?
73 de Martin, G3EDM
|
I have not touched a Mac in a decade.
But a geek site reports that Mac is going to be less friendly toward un-signed apps:
"... The right-click/control-click option for easily opening unsigned apps is no longer available. Users who want to open unsigned software will now need to go the long way around to do it: first, ... ... ..."
The essay also says why this matters less for BIG developers, and is critical for "hobby" software like PSUD.
|
Re: Modelling PSUD2 into a voltage regulator
Ian,
?
Thanks for the guidance/idea.
So the concepts is a dirty regulator circuit for the start up and a clean linear non-regulated for the in-use period. = sounds like a great idea :-)
What I am unclear on is the process of transition, and the way to manage the balance of current draw to the dirty circuit and then to only the clean circuit?
?
Rich
?
?
|
Re: Modelling PSUD2 into a voltage regulator
I don't know what the powered circuit is, but all regulators are not
created equal.
They can have enormous phase & impedance non-linearities that
really screw up the sonics.
I can assure you that attention to PS linearity pays huge sonic
dividends.
This thread from 2009 goes into the detail.
As far as the PSU, why not parallel a high current winding feeding a
simple transistor regulator with a lower current precision one.
After the appropriate time, the high current can be shut off.
To avoid a transient, kill the high current winding input at the
line zero crossing
More complicated in some aspects for sure.
As simple as possible in others
Cheers,
- Ian
On 7/22/2024 03:07, Tonescout wrote:
toggle quoted message
Show quoted text
Duncan,
?
This is great! thanks so much
?
I have only designed power supplies that are not regulated
before :-)
?
That approach makes life very simple!
?
I can also add a capacitor after the Regulator, when I looked
at this unit (an alternative one I might consider) the
application of a 100uF seemed useful.
?
|
Re: Modelling PSUD2 into a voltage regulator
Duncan,
?
This is great! thanks so much
?
I have only designed power supplies that are not regulated before :-)
?
That approach makes life very simple!
?
I can also add a capacitor after the Regulator, when I looked at this unit (an alternative one I might consider) the application of a 100uF seemed useful.
?
https://www.mouser.co.uk/datasheet/2/268/MIC29510_12_5A_Fast_Response_LDO_Regulators_DS2000-3443948.pdf
|
Re: Modelling PSUD2 into a voltage regulator
Thanks Rich.
?
For the load, is it a motor or something like that? Just trying to get my head round why the startup current is 10x the run current.?
?
Some feedback on the PSU, not trying to pick it apart, just some thoughts:
?
- There's quite a bit of resistance in the chain. Adding it up in my head it's over 3 ohms. A 3 amp draw will cause a minimum of 9 volts drop, and the resistance in the earlier part will cause much more. The chart bears this out - there's a drop of 12 or 13 volts between the low current and the high current draw
- As you are feeding into a regulator, some ripple is OK on the output of your PSU. The solid state regulator from your datasheet has a line regulation of 0.015%. That means it will cut the ripple going in by 6000-7000 times. So some ripple is OK as long as the "trough" of the cycle doesn't drop below the dropout value of the regulator
- The RC sections will give a small amount of ripple reduction but will mess up the regulation. Again, think about how much ripple is OK and drop the RC sections. And probably the LC too
- If I was having a go at this, I would probably just have transformer, bridge, capacitor. And that's it. Nice and easy, compact and should give better regulation
- The 16.5V seems high for a 5V regulator, would need to keep an eye on power dissipation as it's a linear regulator
?
Putting all the above into practice, I've clipped an example where I've used a 9V / 3A (10% regulation) transformer into a simple capacitor. On the high current draw there is about 3V peak to peak of ripple. That may look bad, but the regulator will get it down to 0.0005V which may or may not be OK for your application. The light load rises to 12V which means your regulator will drop 7V @ 0.25A which is 1.75W, but worse is the 3A draw where it will lose 12-15W. I skimmed the data sheet for a power envelope but couldn't quickly find anything, just some stuff about how it limits the power by shutting down automatically.
?
Hope this is some help to you.
?
?
Regards,
Duncan
?
?
|
Re: Modelling PSUD2 into a voltage regulator
Duncan,
?
Thanks for this; for some reason I had to really play with the circuit it get it to produce reasonable voltages in both scenarios.
This is the regulator I was looking at https://www.ti.com/lit/ds/symlink/lm1084.pdf?ts=1721541195139&ref_url=https%253A%252F%252Fwww.mouser.com%252F
?
The start up current is 2.5>3A and running 240-260mA so this is what I ended up with.
?
Rich
|
Re: Modelling PSUD2 into a voltage regulator
There's a couple of things I can think of.
?
First is to ensure that the voltage feeding the regulator doesn't drop below the dropout voltage. You'd have to check the data sheet, but say the dropout for your 5V regulator is 6V then ensure that it doesn't drop below that. You probably want to add safety margin for component tolerance, lower than normal mains voltage, etc.
?
Second thing is you can simulate the environment with a stepped load. This could be 3A for N seconds then change to 240mA after that.
?
Set up stepped load
?
- Right-click in the load box (outside of the resistor itself), select Change then select type of load as Constant current.
- Right-click on the constant current symbol click edit, then click the stepped load box
- Value 2 and After will light up, so you can key in value 1 of 3A, value 2 of 240mA and the delay between the two you would have to decide for yourself as you know best what the timings are
?
Regards,
Duncan
?
|
Modelling PSUD2 into a voltage regulator
I have a design I want to explore to power a 5V device that consumes up to 3A on start up as the system boots up and consumes more power, and then settles and takes a steady state at 240mA
?
How is this best modelled to make sense of the war DC design before the regulator
?
Any ideas/experience?
?
Thanks
|
Locked
Re: This marvellous and 'easy to use' programme fails for the simple and very obvious reason that there is no guide on how to its use it (nor, apparently, any intention to provide such...)
There's a guide in the help file which explains how to use the software and a video on how to make up your own custom rectifiers. Every on-topic question I get on here gets answered by me personally, so nobody is left trying to figure out how things work.
I'm struggling to see why someone would continue to operate a "useless" piece of software between 2006 and 2024 (a total of 18 years!), also you've been a member on here since 2020 and you've been provided with help on every question you've posted.
Congratulations on becoming the first person I've had to block from posting on this forum.
Regards,
Duncan
|
Locked
Re: This marvellous and 'easy to use' programme fails for the simple and very obvious reason that there is no guide on how to its use it (nor, apparently, any intention to provide such...)
I found it intuitive and useful from the first click, but then I worked 45 years as an electrical engineer...? I think you need a bit more background first.? I'd suggest you Google "Vacuum tube amplifier power supply design", read a few of the articles.? If none of them make any sense, you might try the Navy training course on vacuum tubes and power supplies - search "NEETS module 6" and it'll pop up.? If you've never used the power tools in a metal shop, don't start without some training - you can make a mess out of a job easily, even if you manage to keep both eyes and all of your fingers.? Some tools are like that.
|
Locked
This marvellous and 'easy to use' programme fails for the simple and very obvious reason that there is no guide on how to its use it (nor, apparently, any intention to provide such...)
…and the question ‘where can [I] find a guide,’ or very similar, has been asked since at least 2006… except, all we get is avoidance and/or ‘nice’ obfuscations…
Personally, I have come to the conclusion that PSUD(x) is useless (to myself) as it stands. And… that is a great shame on tts author? How many of us wish it were otherwise?
|
Re: Resistor at center-tap
Is there some reason you can't lower the input voltage.
I built this two stage bucker to lower our 120v+ to ≈117
is case the link is stripped.
- Ian
On 6/30/2024 06:46, Tom Bavis wrote:
toggle quoted message
Show quoted text
[Edited Message Follows]
Topic locked, so I'll start a new one.
A resistor inserted at the center tap of a full-wave rectifier
acts the same as adding two resistors of the same value, one in
series with each diode, and could be modeled as extra resistance
in the secondary. Of course the dissipation? is doubled (RMS
current is 1.4 times what is modeled).? This could also be used
provide a negative bias voltage, though it's not much different
from cathode bias.? Often called "back bias".? Definitely out of
PSUD territory...
|
Topic locked, so I'll start a new one.
A resistor inserted at the center tap of a full-wave rectifier acts the same as adding two resistors of the same value, one in series with each diode, and could be modeled as extra resistance in the secondary. Of course the dissipation? is doubled (RMS current is 1.4 times what is modeled).? This could also be used provide a negative bias voltage, though it's not much different from cathode bias.? Often called "back bias".? Definitely out of PSUD territory...
|
Paul Reid
Tonescout
Ian Eales
