ebay board kits v 542 boards

[Jonathan]

how you worked that out i have no idea.. as grey is 115v and violet is 0 volts.

The position of the black dot on the diagram shows the relative polarity of the windings, so if a primary wire with a dot is connected to one without, and the other two are connected to the mains that's correct for 230V. If the dotted wires are connected together, then to the mains and similarly for the wires without the dot then the primary windings are in parallel and in phase, so 115V is required - i.e. ideal for the countries with 115V mains (e.g. USA). Any other connection is not permitted since it will involve connecting the windings 180° out of phase, so they'll approximately cancel and you'll get nothing.

also on the description ie. 500va 0-35 0-35.

does this mean its 70v output.

If you put the two secondary windings in series then yes you would get 70V, however we want them in parallel to get 35V at twice the current as if they were in series. Most transformers are wound with at least two secondaries to give you this option.

[crossleymarko]

The position of the black dot on the diagram shows the relative polarity of the windings, so if a primary wire with a dot is connected to one without, and the other two are connected to the mains that's correct for 230V. If the dotted wires are connected together, then to the mains and similarly for the wires without the dot then the primary windings are in parallel and in phase, so 115V is required - i.e. ideal for the countries with 115V mains (e.g. USA). Any other connection is not permitted since it will involve connecting the windings 180° out of phase, so they'll approximately cancel and you'll get nothing.



If you put the two secondary windings in series then yes you would get 70V, however we want them in parallel to get 35V at twice the current as if they were in series. Most transformers are wound with at least two secondaries to give you this option.

so secondry in series on the diagram would be red 70v+ , yellow and black joined. orange -v

sorry here is a good detailed page.. http://www.routoutcnc.com/PowerSupply.pdf

[crossleymarko]

ok so i got it, apparently times your ac voltage by 1.4... right gonna go with it i think.. been looking at maplins,?

off the shelf 225va 2x35 3.2a,39.99. not as good as your link to rapid johnathon, i know but what do ya think.

thanks all

[m_c]

ok so i got it, apparently times your ac voltage by 1.4... right gonna go with it i think.. been looking at maplins,?

off the shelf 225va 2x35 3.2a,39.99. not as good as your link to rapid johnathon, i know but what do ya think.

The proper figure is the square root of 2, which is roughly 1.412, however the rated output voltage of the transformer is with the it under the rated load, so off load the voltage is normally a few percent higher, and you need to allow that mains voltage can drift up and down, so you need to allow some margin for error.

Also check out http://www.airlinktransformers.com/ for transformers.

[crossleymarko]

thanks what range of va am i looking at. ie 300va 0-35 0-35