Rank: Member
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Joined: 8/5/2009(UTC)
Posts: 6
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Hi,
How many VA's the 7V transformer needs to be to drive 2*Volumite, 2*controller, and 2*Joshua Tree?
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Rank: Member
Groups: Member
Joined: 8/5/2009(UTC)
Posts: 6
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Since LM7805CT is rated for 1A, am I correct to calculate:
Dropout Voltage = 2V
min. Voltage in = 5V + 2V = 7V
Minimal dropout current
2KBP01M Bridge Rectifier:
Forward Voltage @ 1A = <1V
min. Voltage in = 7V + 1V = 8V
Minimal dropout current
Transformer:
min. Voltage Out = 8V/sqrt(2) = 5.7V
So, at minimum 6V 1A transformer can power one of everything.
For the whole set 15VA 2*7V should be safe and enough?
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I would think that should work fine.
But you might want to go slightly larger if you have the space just to be safe.
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Rank: Member
Groups: Member
Joined: 8/5/2009(UTC)
Posts: 6
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Thanks!
I'm currently planning to use 30VA 9V toroid. PSU will produce 5V 3A to power the units.
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