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VCT Transformer

PostPosted: Mon Jul 07, 2014 1:22 pm
by MacL
Hi All,
I built a power supply a few years back and I am thinking of using it for a small project... anyway I am trying to understand my VM reading.
Using a 20 VCT transformer - I added a few caps and two diodes on each leg. I am getting 15.6 volts on each leg unloaded (and 31.2 across - & +).
I am trying to understand why or what this will be putting out once it is under load. The voltage x 1.4 or 1.2 doesn't seem to "add up"?
What am I missing? I though it would be 10v x 1.4 or 14 volts or maybe a little less. It's appears to be a well built Triad transformer.
Thanks

Re: VCT Transformer

PostPosted: Mon Jul 07, 2014 8:36 pm
by Geek
What's your line voltage?

Triad datasheets show a 25% transformer regulation.

Cheers!

Re: VCT Transformer

PostPosted: Tue Jul 08, 2014 5:51 am
by MacL
122 volts! Just moved into this apartment two months ago and have never checked the line voltage...
So transformer is rated at 115v - so I have about 6% more volts than transformer was designed to use.
So I guess that would account for about 1 volt extra? What does 25% regulation mean?
Appreciate the input Geek!

Re: VCT Transformer

PostPosted: Tue Jul 08, 2014 11:54 am
by Geek
25% regulation means the AC side unloaded to full load falls about 25%. This way you can figure the minimum voltage it'll output from a rectifier/filter for your circuit and the maximum unloaded for the cap voltage ratings ;)