[ARC5] 28VDC Regulator

[Rich Post]

Wayne,

Does the transformer have other secondaries?  Most of the older solid state
receiver transformers have a 12-15 volt source also.  If so, hook that in
series with the primary, or hook it up as a bucking source to the primary.
I have also rescued a few such transformers, including one that had enough
secondaries which when hooked in series made a useful isolation
transformer.   And yes, several 2N3055 pass transistors with bases fed by a
low current regulator source make that a nice regulated PS.   I have also
recycled the output transistors for pass regulation as well as the heat
sink, assuming you have discrete transistors for output as opposed to a
large IC.

Rich KB8TAD


On Sun, Jul 1, 2018 at 6:43 PM, Robert Eleazer <releazer at earthlink.net>
wrote:

> Today I found a Toshiba AM/FM stereo receiver someone had thrown out.  It
> was dead but yielded a  nice big heavy transformer that has a number of
> outputs, including one with 64VCT.  I still would like to build a dedicated
> 27.5VDC power supply that could run my ARC-114 and ARC-116.  They run fine
> on my variable bench power supply.  I have found the LM317 and related
> series to be inadequate due to its input voltage limitation.
>
> I looked at the  LM338 specs and it does not refer to an input voltage
> limitation, although max output is 32VDC and output versus input cannot be
> greater than 40VDC. That 64VCT transformer will give me about 45VDC cap
> filtered input to the regulator.
>
> So, do y'all think the LM338K will do the job? Needless to say I would
> rather stay linear and not use a switcher.
>
> Thanks
>
> Wayne
> WB5WSV
>
>
>
>
> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient> Virus-free.
> www.avg.com
> <http://www.avg.com/email-signature?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=emailclient>
> <#m_-8102347568631960738_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
>
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: http://www.qsl.net/donate.html
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/arc5/attachments/20180701/74141ee2/attachment.html>