Re: [CAD_CAM_EDM_DRO] Re: Power supply

----- Original Message -----
From: "Stephen Wille Padnos" <spadnos@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: Saturday, June 24, 2006 12:47 PM
Subject: Re: [CAD_CAM_EDM_DRO] Re: Power supply


> He's saying that the output from the buck transformer should be
> connected on the *primary* of the larger transformer, to reduce the
> input voltage by roughly 10%.
>
> In that case, 4A in the primary of the main transformer (and the
> secondary of the buck transformer) would allow roughly 440W at the
> secondary (I think he forgot to subtract the 12V from the input voltage,
> so it's 4 * 108 = 436W)
>
> This will reduce the final output voltage by only about 6V, rather than
> a 12V reduction if it were on the secondary.
>
> - Steve
>
> Peter Reilley wrote:
>
>>A .05 KVA transformer that is driving a perfectly
>>resistive load is capable of supplying 50 Watts.
>>There is no getting around that 50 Watt limit.
>>Volt-Amps (VA) is the same as Watts for a
>>resistive load.
>>
>>This transformer can supply about 4 Amps at
>>12 volts or about 2 Amps at 24 volts. It will
>>draw about .4 Amps if the primary is wired
>>for 120 Volts or about .2 Amps at 240 Volts.
>>
>>>From this it can be deduced that the wire used
>>in each of the two secondaries is capable of carrying
>>about 2 Amps. The wire in each of the two
>>primary windings is capable of carrying .2 Amps.
>>You cannot exceed these current limits without burning
>>up the transformer.
>>
>>Pete.
>>
>>
>>
>>
>>----- Original Message -----
>>From: "David Speck" <Dave@...>
>>To: <CAD_CAM_EDM_DRO@yahoogroups.com>
>>Sent: Saturday, June 24, 2006 11:49 AM
>>Subject: Re: [CAD_CAM_EDM_DRO] Re: Power supply
>>
>>
>>
>>
>>>Peter,
>>>
>>>It's true that the buck transformer is rated at 4 amps, but if applied
>>>to the primary side of the power circuit as is usually practiced, then
>>>that means you would be drawing 4 amps through the 120 volt primary, or
>>>delivering about 480 watts to the secondary of the original
>>>transformer. The original enquirer didn't spec the size of the original
>>>transformer, but 480 watts sounds like a reasonable initial guess.
>>>
>>>Dave
>>>
>>>Peter Reilley wrote:
>>>
>>>
>>>>That transformer is not adequate.
>>>>It is spec'ed as .05KVA. That means that it is good
>>>>for about 4 Amps when wired for 12 Volts.
>>>>
>>>>Pete.
>>>>
>>>>----- Original Message -----
>>>>From: "David Speck" <Dave@...>
>>>>To: <CAD_CAM_EDM_DRO@yahoogroups.com>
>>>>Sent: Saturday, June 24, 2006 10:39 AM
>>>>Subject: Re: [CAD_CAM_EDM_DRO] Re: Power supply
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>>This buck / boost transformer would do the job for $29.99 w/ $10.00
>>>>>shipping on eBay's "Buy it Now"
>>>>>
>>>>>Dave
>>>>>
>>>>>GE BUCK BOOST TRANSFORMER CATALOG# 9T51B0102 Item number: 3853854254
>>>>>
>>>>>====+====+====+====+====+====+====+====+====+====+====+====
>>>>>
>>>>>Robert Campbell wrote:
>>>>>
>>>>>
>>>>>
>>>>>>Tony,
>>>>>>
>>>>>>I am with you. PartsExpress has transformers for about $70 which are
>>>>>>affordable.
>>>>>>
>>>>>>
>>
>>
>>
>>Addresses:
>>FAQ: http://www.ktmarketing.com/faq.html
>>FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
>>Post Messages: CAD_CAM_EDM_DRO@yahoogroups.com
>>
>>Subscribe: CAD_CAM_EDM_DRO-subscribe@yahoogroups.com
>>Unsubscribe: CAD_CAM_EDM_DRO-unsubscribe@yahoogroups.com
>>List owner: CAD_CAM_EDM_DRO-owner@yahoogroups.com, wanliker@...,
>>timg@...
>>Moderator: pentam@... indigo_red@... davemucha@...
>>[Moderators]
>>URL to this group: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO
>>
>>OFF Topic POSTS: General Machining
>>If you wish to post on unlimited OT subjects goto:
>>aol://5863:126/rec.crafts.metalworking or go thru Google.com to reach it
>>if you have trouble.
>>http://www.metalworking.com/news_servers.html
>>
>>http://groups.yahoo.com/group/jobshophomeshop I consider this to be a
>>sister site to the CCED group, as many of the same members are there, for
>>OT subjects, that are not allowed on the CCED list.
>>
>>NOTICE: ALL POSTINGS TO THIS GROUP BECOME PUBLIC DOMAIN BY POSTING THEM.
>>DON'T POST IF YOU CAN NOT ACCEPT THIS.....NO EXCEPTIONS........
>>bill
>>List Mom
>>List Owner
>>
>>
>>Yahoo! Groups Links
>>
>>
>>
>>
>>
>>
>>
>>
>>
>