Re: Calculating DC Output Current From Unregulated AC Transformer
- From: John Fields <jfields@xxxxxxxxxxxxxxxxxxxxx>
- Date: Fri, 11 Jul 2008 15:34:47 -0500
On Fri, 11 Jul 2008 12:29:09 -0700, The Phantom <phantom@xxxxxxx>
wrote:
On Wed, 9 Jul 2008 18:26:12 -0700 (PDT), emailaddress@xxxxxxxxxxxxx wrote:
I have an application in which I need to determine if a transformer is
suitable.
Transformer is rated for 12VAC, 1.67A but I need DC. I could put a
bridge rectifier and capacitor after it easily enough but how does one
go about calculating the DC output this is capable of?
I've previously used a x 1.41 factor to convert which would give
16.92V, minus the forward drop of a couple silicon diodes in the
bridge rectifier estimated at roughly ( 2 * 0.7V, ignoring changes in
diode forward drop at different current) which would leave (16.92 -
1.4) = 15.5V, but am I correct in thinking this is peak DC output and
there is a different calculation needed to arrive at the output
voltage if the load were drawing 1.67A?
Perhaps a little more info about the project is in order. Following
the transformer there'll be a bridge rectifier, smoothing cap... then
a linear regulator suppling constant current to charge batteries. The
circuit is a bit more involved than only this (protection diodes,
charge controller, etc) but this is the subsection in question and the
rectified output of the transformer will need to stay above roughly
12.3VDC so I'm trying to figure out what constant current this
transformer (or others) can supply. I've alread accounted for other
looses like that through the regulator when coming up with the 12.3V
figure.
How much rectified DC voltage can that transformer maintain at 1.67A?
How much current can it maintain while staying at or above 12.3V, or
if there is another voltage to consider because we don't know the
other properties of this transformer, what voltage would that be and
at that voltage what is the DC current capability?
Please I'm asking to learn how to calculate this myself instead of
only the numerical answer.
Thanks,
JC
You should go to the library and make a copy of the paper:
"Analysis of Rectifier Operation", O. H. Schade, Proceedings of the IRE,
July 1943
This will give you an idea of what's involved in a detailed analysis of the
sort you're asking for.
---
There's also Motorola's Silicon Rectifier Manual, an excellent
reference and cheap at:
http://www.amazon.com/gp/offer-listing/B000HVEWGK/ref=dp_olp_3/103-7647257-4204638
JF
.
- Follow-Ups:
- References:
- Calculating DC Output Current From Unregulated AC Transformer
- From: emailaddress
- Re: Calculating DC Output Current From Unregulated AC Transformer
- From: The Phantom
- Calculating DC Output Current From Unregulated AC Transformer
- Prev by Date: Re: Calculating DC Output Current From Unregulated AC Transformer
- Next by Date: Re: Calculating DC Output Current From Unregulated AC Transformer
- Previous by thread: Re: Calculating DC Output Current From Unregulated AC Transformer
- Next by thread: Re: Calculating DC Output Current From Unregulated AC Transformer
- Index(es):
Relevant Pages
|
