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Since this shouldn't have been an issue from the software, I've contacted the guy I bought the laptop from to see if he can help.?
It was a struggle to make the Excel program do what you showed in the video, this admin stuff is beyond me.
Would be nice if you ever feel like doing an updated video to show the steps taken to make all the equations copy and paste?
I had to manually do it, but it works. Even figured out the graph. I've attached the screen shots of the bridge recs I'm trying to use in the sim.

V2.22 VER 76, it is under the Program files (x86)
folder

This is a system issue. The folder is located on the system disc that needs admin rights to write data.?

PSUD was updated in 2019 to move storage of the rectifiers to the AppData area instead of the Program Files area. This was mandated by security changes on Windows 10 which prevented writing data to program areas so the previous version from 2017 would not run correctly.

Hence my question to the OP on what version they were running.

If you are running lower than version 2.10.0 / build 63, I would strongly recommend upgrading as your software is 6+ years out of date. The most recent Windows versions of PSUD2 are stored here ->?/g/duncanampspsud/files/psud2_windows

Regards,
Duncan


Regards,
Duncan

This is a system issue. The folder is located on the system disc that needs admin rights to write data.?

You can either run the program as an administrator (right-click on the icon and choose this option), or install it to the other drive (this may not actually help if the folder path is hard coded into the program).?

Yet another solution is to change access permissions for that particular folder, this is a more involved solution though.?

On 8/12/2023 6:54 PM, Eric W via groups.io wrote:

capacitors have a resistance field. The start up schematic has 2 ohms

This of this as "lead resistance".

Actually in electrolytics it is more like "paste resistance", the semi-damp electrolyte between the electrodes. In foil caps, foil resistance too.

If this series resistance could be ZERO, then INFINITE current could flow for an instant, and blow-up other parts. And blow-up the mathematics, which does not have infinite fingers to count on. Fortunately ZERO resistance doesn't happen in our everyday world.

120, 1K, and 10KHz, should use the lowest resistance? ie 120Hz?

Use the number for (nearest) YOUR power frequency. In 60Hz lands with full wave rectifier, the 120Hz number is perfect. Probably close-enough for 50Hz power or half-wave rects (DCR changes little with frequency). If on the other hand you are messing with power vibrators (1940s car radio) or switching supplies, you are filtering for 400Hz to 40kHz and should use the high-frequency numbers.

Shouldn't this be in the megaohms for a cap?

That's shunt (parallel) resistance. Yes, much higher than your load. May be "only" hundreds of Kohms for a high-uFd electrolytic, even less first thing after long storage; but the cap makers know it must be "negligible" compared to load or you will complain about waste power and heat. (Hasn't been a problem in almost 100 years?)

Forgot I can measure ESR, the ESR readings are at 120, 1K, and 10KHz, should use the lowest resistance?

This is for series resistance. All capacitors have this, and it contributes to reducing the current that can flow in and out of a capacitor and therefore its effectiveness.

It's a necessity to make the simulation work, and manufacturers of capacitors (decent ones, anyway) will publish figures for the series resistance. Sometimes it's displayed on the data sheet as ESR (Effective Series Resistance), hope this helps.

Regards,
Duncan

Thanks! I'll check that out.
One more question, the capacitors have a resistance field. The start up schematic has 2 ohms here. Shouldn't this be in the megaohms for a cap? I don't understand where this measurment is derived from.

There's some resources which should help with this. You will need a data sheet (that's a must) but once you have this, the process is quite simple; there's a YouTube video which describes the process in some detail and some spreadsheets in the files area which help.

The YouTube video is at ->?

There's a couple of spreadsheet files here in groups.io that help with solid state and vacuum tube rectifier modelling ->?/g/duncanampspsud/files/documentation

Hope this helps.

Regards,
Duncan

Any possibility of having you add a GBL06 and GBU806 rectifiers to the list? I really don't understand how to find the "vlaw / vfac / and dres" fields.?

ps: Don't forget the primary resistance as this forms part of the source impedance.

Regards,
Duncan

Hi, you just measure one half.

As you say, they are likely to be different; I would recommend measuring across both (red to red) and dividing by 2 for our purposes (both volts off-load and ohms).

PSUD3 will allow a different off-load voltage and resistance for each half of the secondary.

Regards,
Duncan

(red-ct-red)? For full wave rectifier, do we enter the measured full (red-red) Secondary winding's DC resistance into the Secondary winding resistance field of the Calculator?? Or, do we enter only half (red-ct) of the full winding's DC resistance value? ?
If the later, should we take the measured red-red ohm value and divide by 2 since the two red-CT values are never identical?
(The off-load voltage of the two halves of the winding are never identical as well so I assume we use the full red-red voltage value divided by two.)

Thank you! and thank you for PSUD2!!!

Regarding the offline transformer voltage to use. When I have the actual transformer, I measure the actual secondary open circuit voltage. With the transformer already in the circuit, which I think is so in your case, I would just pull out the 5Y3 rectifier so you can measure the unloaded voltage. You can also measure the actual secondary resistance with the circuit powered down. I realize that you are already on the path to fix an issue with PSUD2 but it's nice to know the actual characteristics of your power transformer when possible. When I do the measurements that I described, I often find variations from the printed schematic values.
Cheers,
Tom

Hi Jonah,

The thump is to be expected - the CLC filter is a resonant item. Solid state rectifiers apply power straight away and the sudden increase in voltage to the system causes the CLC filter to resonate slightly. I didn't see it on PSUD2 which is what made me think something was wrong.

Regards,
Duncan

Hi Duncan,

Thank you so much for your thoughtful response.?

I thought I was going crazy, glad to know it wasn't just me. I wonder what that thump is all about?

That said, the programs is wonderful and look forward to PSUD3 later this summer.

Best,
Jonah

Thanks for letting me know about the other channel, it was in Japanese, but I should have done the decent thing and waved Google Translate over it, apologies.

I've keyed your schematic into PSUD2 and I'm getting exactly the same results. I tried it in (the unreleased) PSUD3 and it's giving 10V more and a "thump" at the start. So there's a problem in PSUD2. If you simulate PSUD2 for about 10-20mS it shows a substantial amount of dithering so the simplified model is getting confused.

Here's what PSUD3 shows:



Here's the bump at the start in more detail:



By increasing the transformer off-load voltage to 260V which is a typical value (base + 8%) it will give 257-258V output. However, the results are still low on PSUD2, here's the dithering at the start of the simulation I mentioned earlier - a sure sign that it's struggling to do the calculations:



Conclusion: PSUD2 has some holes in the simulator and they are showing up on the schematic you keyed in. There's no bug fix that I can apply as the PSUD2 simulator engine is broken as designed. I'll put a beta of PSUD3 out on here about 2nd / 3rd week in August; being a beta it will probably have a few issues of it's own but at least it's accurate and any issues that are found should be fixable.

Regards,
Duncan

Thanks for the clarification regarding off-load voltage and rated voltage.

About the current draw... the schematic is for a stereo amp so I estimated around 96mA for two 6V6 and two EF86. The arrow at the node that reads 258V translates as "To other channels."

That said, maybe I'm reading the schematic wrong and the 258V reflects only that one side of the amp... but wouldn't you model the entire current draw (all tubes) on the power supply?