[ARC5] [Milsurplus] Quieting A DC/DC Converter

[Scott Robinson]

Folks,

It's possible to build switching supplies that are 90+ percent efficient 
(resonant mode topologies) but flybacks are cheaper so that's what you 
generally get.

The 4 kW supply I have been building at work does this.
eace,

Scott


On 1/18/18 12:22 PM, Bob kb8tq wrote:
> Hi
> 
> You will not *hear* the 75 KHz by ear, but it will get into your radios. 
> It takes a bit of effort to
> filter *both* the input and output for RFI. That said, no, you can’t 
> come close to anything like
> this price on a roll your own basis.
> 
> Best guess on efficiency (based on similar units) is around 70%. Running 
> 40W out you will have
> almost 60W in. That cute little PCB could be trying to dump near 20W 
> into the surrounding area …..
> (yikes !!) …. they will get warm …. Even 80% and 10W off the board would 
> get toasty without some
> moving air.
> 
> Bob
> 
>> On Jan 18, 2018, at 3:00 PM, Jim Whartenby <antqradio at sbcglobal.net 
>> <mailto:antqradio at sbcglobal.net>> wrote:
>>
>> These are interesting modules Dave.  Several are available for under 
>> $5 each with free shipping.  All seem to be rated for 40 watts so at 
>> the maximum 390 VDC output, one has 100 mA available.  Can't 
>> roll-your-own for twice the money!
>>
>> Does anyone have experience in using this module with 28 VDC input and 
>> around 250 VDC output?  Wonder what the efficiency is in this 
>> condition?  Operating at 75 kc, it should be as quite as a church 
>> mouse and easy to filter.
>> Jim
>>
>>
>> ------------------------------------------------------------------------
>> *From:* Bob kb8tq <kb8tq at n1k.org <mailto:kb8tq at n1k.org>>
>> *To:* David Stinson <arc5 at ix.netcom.com <mailto:arc5 at ix.netcom.com>>
>> *Cc:* ARC-5 <arc5 at mailman.qth.net <mailto:arc5 at mailman.qth.net>>; 
>> milsurplus at mailman.qth.net <mailto:milsurplus at mailman.qth.net>
>> *Sent:* Sunday, January 14, 2018 6:24 PM
>> *Subject:* Re: [Milsurplus] [ARC5] Quieting A DC/DC Converter
>>
>> Hi
>>
>> One of the “interesting” things about boards like this are the empty 
>> slots on the board
>> for other parts. In some cases the performance can be improved by 
>> putting those parts
>> on the board. In other cases the result is a pretty dramatic burst of 
>> smoke ……
>>
>> Bob
>>
>> > On Jan 14, 2018, at 5:35 PM, David Stinson <arc5 at ix.netcom.com 
>> <mailto:arc5 at ix.netcom.com>> wrote:
>> >
>> > Here's a listing for these DC-DC thingies.  It's
>> > 390 VDC max.
>> >
>> > https://www.ebay.com/itm/142555893852
>> >
>> > ______________________________________________________________
>> > 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 <mailto:ARC5 at mailman.qth.net>
>> >
>> > This list hosted by: http://www.qsl.net <http://www.qsl.net/>
>> > Please help support this email list: http://www.qsl.net/donate.html
>>
>>
>> ______________________________________________________________
>> Milsurplus mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Milsurplus at mailman.qth.net 
>> <mailto:Milsurplus at mailman.qth.net>
>>
>> This list hosted by: http://www.qsl.net <http://www.qsl.net/>
>> Please help support this email list: http://www.qsl.net/donate.html
>>
>>
>> ______________________________________________________________
>> Milsurplus mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/milsurplus
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:Milsurplus at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
> 
> 
> 
> ______________________________________________________________
> 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
>