Re: [Phys-L] AC power calculations

[bernard cleyet <bernardcleyet@redshift.com>]

> On 2021/Feb/22, at 13:06, Daniel MacIsaac via Phys-l <phys-l@mail.phys-l.org <mailto:phys-l@mail.phys-l.org>> wrote:
>
> Actually Bernie, there are a lot of cheapie power supplies out there using capacitive droppers to avoid the transformers in wall warts.  Many LED lamps use these.  
>
> If you buy a super cheap (eg quite lethal when wet) $2 cell phone charger that’s for sure a capacitive dropper.  The Apple charger costs 10X as much, but is much safer (real HV isolation).
>
> Dan M
>
> https://en.wikipedia.org/wiki/Capacitive_power_supply <https://en.wikipedia.org/wiki/Capacitive_power_supply>




Daniel!  


I obviously miscommunicated.  

I meant as a load, i.e.  the cap. across the AC domestic power.  I may try that again to verify.  

One may test if a cap is the connection to the wall wart or a better high freq W/toroid v. low standby consumption P/S (< one watt) if it sparks on connection.  The 65 W  apple book P/Ss (curiously) does this!    The usual, now ancient, transformer types don’t, and standby is often about 4 W.  


bc  uses his kill a watt v. often. He's taken apart many wall warts, but not yet a “modern” one.  (Too valuable and usually potted. He does not like potted electronic.) 

BTW, I previously used a d’ Arsenal type watt meter, but now in the to be repaired box.   They’re very interesting:  The W/Q [1] is the armature, the current is the magnet.  Smart, nicht wahr?    


[1] I suppose nearly universally voltage, which makes as much sense as using feeterage or meterage for length.  But then using voltage indicates not abvolt or statvolt.  OTOH, coutures use yardage.   Oh, I can use pd, except w/q is specific potential.   The English maybe use tension especially in EHT   The French tension, and the Germans a very long word, typical!    (according to google translate)