Where can I find a guide on using this program. I have played with it but without understanding or success. I have looked at DHTROB's article and follow his explanation but when I try and simulate I usually end up with a thick red line which will not go away even after returning to the component value I had before.
I am installing a valve output stage in a cd player and would really like to get the PS right. I have read the help section but find I need a longer more detailed approach. For instance nowhere do I see anything about the time duration required for the simulation or info about what I'm looking at when I zoom in. Any advice welcome. I have searched the forum but only find members specific problems, not an overall tutorial. ??
regards
Charles
I am installing a valve output stage in a cd player and would really like to get the PS right. I have read the help section but find I need a longer more detailed approach. For instance nowhere do I see anything about the time duration required for the simulation or info about what I'm looking at when I zoom in. Any advice welcome. I have searched the forum but only find members specific problems, not an overall tutorial. ??
regards
Charles
The display function is... not terribly intuitive. If you get a thick red line, you either have to zoom in to see detail or zoom out if it's taking up the whole screen. To look at a portion of a display, click and drag a rectangle of the region you're interested in (like selecting an area in Paint).
Usually, I zoom out until detail is lost using the "zoom out" button, then use the above method to zero in on the region of interest.
As for time, it depends on your supply. If you are using a solid state rectifier, it will come up quite quickly, so you can see the "final" voltage and ripple after just a few seconds. With a tube rectifier, you need to add more delay before looking at the output.
Finally, you should check the stability of the supply by using the stepped-load option with a current sink load. Use the expected current draw, then have it step to something like 10-20% more. Use the delay function to look at the output just before and for a few seconds after the step to see if the supply settles to the new value smoothly, or whether there's wiggles as it bounces around.
An example: I have a preamp with a tube rectifier. I expect it to draw 20mA from the supply. OK, I would model it, set the load as a 20mA current sink, have it step to (say) 24 mA after 15 seconds. This gives the supply a chance to warm up before the current step. I would look at the output for 4 or 5 seconds starting after 14 seconds. Check the box next to V(I1). Ideally, the voltage initially will hit your target, then drop smoothly and exponentially to a lower value after the step. If it rings, you've got some work to do, but it's easier to do in sim than with real parts.
I'm not a big fan of sims, but PSUD2 works very well and does a good job of prediction. I use it constantly.
Usually, I zoom out until detail is lost using the "zoom out" button, then use the above method to zero in on the region of interest.
As for time, it depends on your supply. If you are using a solid state rectifier, it will come up quite quickly, so you can see the "final" voltage and ripple after just a few seconds. With a tube rectifier, you need to add more delay before looking at the output.
Finally, you should check the stability of the supply by using the stepped-load option with a current sink load. Use the expected current draw, then have it step to something like 10-20% more. Use the delay function to look at the output just before and for a few seconds after the step to see if the supply settles to the new value smoothly, or whether there's wiggles as it bounces around.
An example: I have a preamp with a tube rectifier. I expect it to draw 20mA from the supply. OK, I would model it, set the load as a 20mA current sink, have it step to (say) 24 mA after 15 seconds. This gives the supply a chance to warm up before the current step. I would look at the output for 4 or 5 seconds starting after 14 seconds. Check the box next to V(I1). Ideally, the voltage initially will hit your target, then drop smoothly and exponentially to a lower value after the step. If it rings, you've got some work to do, but it's easier to do in sim than with real parts.
I'm not a big fan of sims, but PSUD2 works very well and does a good job of prediction. I use it constantly.
Hi Sy,
Thanks for the response. Seems like lots of people have their supplies running perfectly, either that or they don't bother to simulate. Or maybe its just me who fails to understand. If we take the example you chose using 20mA, you recommend using the stepped load option. How do I do this and then step to a higher load. Also how do I use the delay function. This is why I was hoping for a ' how- to guide
Thanks for the response. Seems like lots of people have their supplies running perfectly, either that or they don't bother to simulate. Or maybe its just me who fails to understand. If we take the example you chose using 20mA, you recommend using the stepped load option. How do I do this and then step to a higher load. Also how do I use the delay function. This is why I was hoping for a ' how- to guide
Charles,
To get a more complete picture of operation you can edit the transformer values.
Right click on the schematic for T1, left click on the "edit" box that appears.
A window will pop up offering an RMSV and an Ohms window with button on the right. Left click the Ohms button and you can enter custom data in the fly out.
This will give you a very accurate model of the transformer circuit performance.
Do not re edit this window. If you want to change transformer information save this simulation as a series numbered document and then open the edit structure. You will find that all of your previous data has been changed back to the default design settings and you must re enter the new data.
Also notice that the data window on the main page has peak and RMS data. This is very reliable and can be used to choose component value ratings so you have less of a chance to let the smoke out. I request a sim circuit in PSUD from my customers any time their data seems odd. This is a great tool for communication with another engineer/designer/hobbyist as well as for your own work.
The only place I have trouble with it is for bridge circuits with capacitance only for ripple smoothing. A typical use for this is in a DC heater supply, where in reality 10 volts AC is needed for 12.6 VDC and the AC current required from the transformer is about 1.9 times the DC current. Psud does not model this fairly common circuit well.
Hope this helps some. I am sure there are others who can speak to specific usage, but I do not know of any tutorial and I looked, before just shrugging my shoulders and starting to investigate the quirky interface and hidden abilities.
But, as SY points out, the learning curve is a bit haphazard
Bud
To get a more complete picture of operation you can edit the transformer values.
Right click on the schematic for T1, left click on the "edit" box that appears.
A window will pop up offering an RMSV and an Ohms window with button on the right. Left click the Ohms button and you can enter custom data in the fly out.
This will give you a very accurate model of the transformer circuit performance.
Do not re edit this window. If you want to change transformer information save this simulation as a series numbered document and then open the edit structure. You will find that all of your previous data has been changed back to the default design settings and you must re enter the new data.
Also notice that the data window on the main page has peak and RMS data. This is very reliable and can be used to choose component value ratings so you have less of a chance to let the smoke out. I request a sim circuit in PSUD from my customers any time their data seems odd. This is a great tool for communication with another engineer/designer/hobbyist as well as for your own work.
The only place I have trouble with it is for bridge circuits with capacitance only for ripple smoothing. A typical use for this is in a DC heater supply, where in reality 10 volts AC is needed for 12.6 VDC and the AC current required from the transformer is about 1.9 times the DC current. Psud does not model this fairly common circuit well.
Hope this helps some. I am sure there are others who can speak to specific usage, but I do not know of any tutorial and I looked, before just shrugging my shoulders and starting to investigate the quirky interface and hidden abilities.
But, as SY points out, the learning curve is a bit haphazard
Bud
Choose a current source for your load. In the dialog box, there's a check box for stepped current. Once you check that, you can input initial and after-step, along with time until step.
There is no explicit delay. Reread my post above- you have to tell it when to step and when to sim (and for how long). If you start the sim at a time a second or so before the step and run it for 2-3 seconds, you'll see if your supply is stable.
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