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How much transformer VA headroom is required for sigma25?

sigma25, sigma26, sigma24

How much transformer VA headroom is required for sigma25?

Postby itsikhefez » December 18th, 2016, 5:51 pm

Based on the calculations on the sigma25 page,
For a 6V DC, 600mA load, the result is 6.4W
For 12V DC, 500ma load, the result is 7.5W.

For 6V, I can go with 7VA, 10VA, 15VA.
For 12V, I can go with 10VA, 15VA.

At digikey atleast, I can only find 15VA in toroids.
Are there any issues with going with 15VA ?

How much increase in rating to the calculation is actually needed?
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Re: How much transformer VA headroom is required for sigma25

Postby amb » December 18th, 2016, 7:16 pm

No issue with using a transformer with higher VA ratings as long as it's within reason. A very large transformer will produce stronger magnetic field interference, but something small like 15VA shouldn't be a problem as long as you don't put sensitive audio circuitry right next to it.

The transformer should have a higher VA rating than the sum of the load wattage and heat loss on the voltage regulator.
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