I have been in touch with Duncan, and he has clarified the ambiguous PSUD2 setting of secondary resistance for a full-wave configuration:
"The voltage and resistance are for one leg only. So if a transformer is shown as 170 ohms, it is 340 ohms across the whole winding. The help file covers the voltage but not the resistance so I will update this."
Ciao, Tim
"The voltage and resistance are for one leg only. So if a transformer is shown as 170 ohms, it is 340 ohms across the whole winding. The help file covers the voltage but not the resistance so I will update this."
Ciao, Tim
Hi Tim
That's strange. It goes against what I measured vs. simulated using the manufacturer's own data for single leg static resistance. For single leg of X ohms, I had to enter 2X then calculate impedance to get a correct simulation in PSU II.
I'm using build 43 of his software. Admittedly, I only have two transformers that can be truly set up for full wave with center tap and only tested one of them - one with high enough static resistance so that a difference would be significant.
Ian
That's strange. It goes against what I measured vs. simulated using the manufacturer's own data for single leg static resistance. For single leg of X ohms, I had to enter 2X then calculate impedance to get a correct simulation in PSU II.
I'm using build 43 of his software. Admittedly, I only have two transformers that can be truly set up for full wave with center tap and only tested one of them - one with high enough static resistance so that a difference would be significant.
Ian
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Yes that sounded like a conundrum.
I guess if you were keen then verifying all the measureable items would be a good start, such as transformer winding resistances, and open circuit secondary voltage, and then trying to check the simplest configuration with a known resistive load - perhaps no capacitive filter, just a resistance - but that would need a true-rms meter with ac and dc measurements to cross check the sim. I won't get a chance for a few days to see if I can set up a somewhat similar cross-check.
I guess if you were keen then verifying all the measureable items would be a good start, such as transformer winding resistances, and open circuit secondary voltage, and then trying to check the simplest configuration with a known resistive load - perhaps no capacitive filter, just a resistance - but that would need a true-rms meter with ac and dc measurements to cross check the sim. I won't get a chance for a few days to see if I can set up a somewhat similar cross-check.
Tim
I will go back and redo these measurements with this transformer. Its possibly an odd-ball. I only have one of them. I have a true RMS meter, but don't like to use it on transformers. In the past, I did and it worked fine but then I had to de-gauss a few after, which was a bit of a bother. I have a feeling that the specs I have are suspect. The manufacturer appears no longer available too.
The only other transformer with a center tap is a Hammond, and it is frankly useless for this exercise since its secondary DCR is so low.
In any case. for full-wave rectification simulations I can attest that Duncan Amps PSU II is very accurate.
Ian
I will go back and redo these measurements with this transformer. Its possibly an odd-ball. I only have one of them. I have a true RMS meter, but don't like to use it on transformers. In the past, I did and it worked fine but then I had to de-gauss a few after, which was a bit of a bother. I have a feeling that the specs I have are suspect. The manufacturer appears no longer available too.
The only other transformer with a center tap is a Hammond, and it is frankly useless for this exercise since its secondary DCR is so low.
In any case. for full-wave rectification simulations I can attest that Duncan Amps PSU II is very accurate.
Ian
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