[ARC5] Receiver AC Power Supplies

[Mike Feher]

It has been a long time, but, could it have to do with core saturation? 73 -
Mike 

Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 

-----Original Message-----
From: ARC5 [mailto:arc5-bounces at mailman.qth.net] On Behalf Of
hwhall at compuserve.com
Sent: Friday, December 12, 2014 9:31 PM
To: jeepp at comcast.net; arc5 at mailman.qth.net
Subject: Re: [ARC5] Receiver AC Power Supplies


 Something that was bugging me today....Ohmic copper loss increases as the
square of the increase in current (power equals I-squared x R). Windings
carrying 4amps will dissipate 4 times the heat they did at 2amps. So,
wouldn't a transformer rated 25vct 2amps (delivering 50watts output) run
even hotter if you used it to obtain 12.5volts at 4amps (still delivering
50watts)? Might spell eventual trouble for the insulation around them, if
not for the wire itself.

Wayne
WB4OGM

 

-----Original Message-----
From: DSP3 <jeepp at comcast.net>
To: arc5 <arc5 at mailman.qth.net>
Sent: Fri, Dec 12, 2014 1:35 pm
Subject: Re: [ARC5] Receiver AC Power Supplies



On 12/12/2014 10:28 AM, Robert Eleazer wrote:
> Also, Radio Shack has a 25.2 CT 2.0 Amp Chassis Mount transformer, 
> Model
273-1512 for $14.49.  The RS stores in my area seem to have them in stock.
>
> By the way, that raises a question.  I think I knew once, but when 
> they say a
center tapped transformer has 2 amps of output, do they mean that it can
provide 25.2VAC at 2.0 amps, which would be 12.5 VDC at 4 amps if connected
for full wave rectification?
>
> Wayne
>
Tell you what I was told by Hammond when I was working with them for the
ART-13 transformer suite.  The word they passed was that the current rating
would be, in this case 2 amps... period.  That's the total current that
could be drawn.  I've always thought exactly as you but 
maybe they've changed the way things are rated?   If you use the thing 
in a bridge circuit, the rating is 50%.  It appears that the assumption
being made is that if its CT'ed, that the expected mode.  I have no idea,
though, how R/S rates their xformers.  But then, what do I know....  If'n it
don't sag or smoke.. go with it!

Jeep - K3HVG
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