what's wrong or difficult with adding 100 turns of 1.4mm diameter wire around the toroid?
One could add 50, then wind on the remainder in groups of 10 turns. Bring all the ends to the edge.This then makes an excellent multi tapped (adjustable) primary that will perform very well.
for 1kVA you could probably use 1.3mm diameter wire without any significant difference in performance. 1.2mm diameter wire will probably show a slight increase in the secondary impedance due to the reflected primary resistance.
One could add 50, then wind on the remainder in groups of 10 turns. Bring all the ends to the edge.This then makes an excellent multi tapped (adjustable) primary that will perform very well.
for 1kVA you could probably use 1.3mm diameter wire without any significant difference in performance. 1.2mm diameter wire will probably show a slight increase in the secondary impedance due to the reflected primary resistance.
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If you want that done properly, then you can use a regulator. In Class AB and B this won't generate too much heat.
In the Russian magazine "РАДИО" (= Radio), issue 05-12, there was a very nice circuit purposed for exactly that kind. The guy needed +-27V and used a +-29V source.
The MOSFETS are used as Drainfollowers here and can be used with even the slightest difference between input and output.
If you need the PDF with copyable text, PM me. With that you can use Google translator. But it's not too complicated. The TL431 is used as the regulating element here as usual
In the Russian magazine "РАДИО" (= Radio), issue 05-12, there was a very nice circuit purposed for exactly that kind. The guy needed +-27V and used a +-29V source.
The MOSFETS are used as Drainfollowers here and can be used with even the slightest difference between input and output.
If you need the PDF with copyable text, PM me. With that you can use Google translator. But it's not too complicated. The TL431 is used as the regulating element here as usual
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Several months ago I asked why it has never/rarely been seen an implementation of MOSFET split supply with the same cct for both positive and negative rails.
The concern was that it is almost impossible to get a matched N-channel and P-Channel MOSFET. Here in this magazine, IRF4905 and IRL2505 are used. Those are not even common devices and may be difficult to source...
Really? My my my!!! oh well do you know what it mean? The same as what the hen said when she saw a scrambled egg. "My poor mixed up child!"
Hier woon een in my agterplaas. Of is dit Husse met lang ore.Nico waar kan jy 'n krokkenoster kry? Vertel my as jy KAN!!! Gert
Welcome to the forum Gert. It may be a late welcome but never-the-less, hope tp see many posts by you.
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Yup. Just curiosity. I have seen many regulators with difficult-to-find mosfets, or even non-complementary mosfets, but never/rarely seen exact copy like the one I used. Just a little worry
45 volt regs
Nico if you want to use two positive regulators to give you the two polarity supplies then two windings or two transformers WILL BE MANDATORY . The only way around this is to use an amplifier that can handle 100volts and then use the loudspeaker output pin as the "Ground" or "0" lead. The basic circuit will be the same as those that can be read in the LM380 power amp specs. (I tried this but with lower currents and voltages) With this amp I could draw enough current for a supply up to 500mA. Therefore two SEPARATE supplies must be constructed each with its own smoothing and rectifier circuit. All that is done is to connect the two in "series" and to use the common point as the "zero" of your supply. If you want to make them to "track" in a variable system then a high quality tandem potentiometer should be used I think that this get too involved! I think that I've seen a dual regulator chip's specs made by National Semiconductors. They were quite expensive . I hope this help. Just keep in mind that the old LM317 CAN ONLY ABSORB 15 WATTS so if you want to go for more power then LM338KSTEEL will have to be used. JUST KEEP IN MIND THAT THE DIFFERENCE between your input voltage and the output that you need MUST NEVER BE ABOVE 30 (THIRTY) VOLTS . So if you want to work with a higher in/out difference then a high voltage regulator will be needed. If you do not need it down to zero then it will work say 25 to 55 volts variation then go for it but be careful and work out your values of the adjusting voltage that it CANNOT go below the safe tension.
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