[ARC5] Cool New DC-DC Converter

[Peter Gottlieb]

Also, watch out for the power ratings.  A 25 Watt converter with an output range 
of 30-400 VDC might well only give 25 Watts at a particular output voltage, 
maybe 350 Volts.  At half that voltage it might only give half output power 
before overheating or burning out.  You really don't know exactly what you will 
get with these dirt cheap Chinese modules.

Peter
kb2vtl


On 3/18/2018 12:12 PM, Bob kb8tq wrote:
> Hi
>
> The real point is that a “250V” cap may or may not have a max rating of exactly 250.0V.
> It may indeed have an actual max voltage on that sample a bit higher than 250V. These
> days it’s very much a “who knows” sort of thing.
>
> Oddly enough the same rule that says “don’t use the last 10	%” also says “don’t use less
> than 60%” on an electrolytic cap. Learned that one in a design review …. on product headed
> for space no less …. gulp ….
>
> Bob
>
>> On Mar 18, 2018, at 12:06 PM, Scott Robinson <spr at earthlink.net> wrote:
>>
>> Well, a switching power supply designer who is even older than I am told me that if you avoid the using the last 10% or so of an electrolytic cap's voltage rating that it will last longer.
>>
>> FWIW,
>>
>> Scott Robinson
>>
>> On 3/18/18 7:33 AM, Bob kb8tq wrote:
>>> Hi
>>>
>>> In some cases, indeed a 250V cap is quite happy for a very long time at 300V. It’s not
>>> all “great balls of fire” sort of stuff ….
>>> Bob
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