XPost: alt.home.repair, uk.d-i-y   
   From: rod.speed.aaa@gmail.com   
      
   "Max Demian"  wrote in message   
   news:psKdne6Qrs3cy-HBnZ2dnUU78KfNnZ2d@brightview.co.uk...   
   > On 03/03/2019 21:08, Rod Speed wrote:   
   >>   
   >>   
   >> "Max Demian"  wrote in message   
   >> news:U5Gdnfm02MNroOHBnZ2dnUU78cvNnZ2d@brightview.co.uk...   
   >>> On 03/03/2019 18:59, Mark Lloyd wrote:   
   >>>> On 3/2/19 1:20 PM, Art Todesco wrote:   
   >>>>   
   >>>> [snip]   
   >>>>   
   >>>>> Here's the way it is.  There are 2 full wave rectifiers.  The DC   
   >>>>> outputs are connected together; + of each and - of each.  These feed   
   >>>>> the converter which is the standard chip, pulsing a transformer.  The   
   >>>>> output of this is 1/2 wave rectified, filtered and goes to the string   
   >>>>> of LEDs. Now back to the 2 full wave rectifiers (FWR).  One input to   
   >>>>> the 1st FWR comes from a pin on one end of the tube and the other   
   >>>>> input to the 1st FWR comes a pin on the other end.  The 2nd FWR is   
   >>>>> wired the same way, except it uses the unused pins on the ends of the   
   >>>>> tube.  For some reason there is a 5 ohm resistor in 3 of the 4 inputs   
   >>>>> to the FWRs.  The 4th is direct connected.  But if you trace is out,   
   >>>>> you can supply 120 VAC to any 2 pins and it works.  You can even power   
   >>>>> from one end and short the pins on the other end and it still works.   
   >>>>> Clever!   
   >>>>   
   >>>> And I seem to remember some that work on any supply voltage from 120V   
   >>>> to 277V.   
   >>>   
   >>> Did anyone need to run a TV on DC,   
   >>   
   >> Yeah, a small portable CRT TV could run on 12V   
   >   
   > "Obviously" I was talking about DC *mains*. Portables that you could run   
   > off a car battery as well as AC mains were available in the eighties (and   
   > beyond no doubt).   
   >   
   >>> or was it just to save having a heavy mains transformer?   
   >>   
   >>> There were certainly AC/DC *radios* that would cope with 120V to 250V or   
   >>> so. Needed a whopping great dropper resistor when working on the higher   
   >>> voltages. I used to have such a (portable valve) radio which would work   
   >>> on battery as well.   
   >>   
   >> Yeah, my first portable radio did it that way.   
   >   
   > *Valve*??   
      
   Yep, full line of valves designed for that situation.   
      
   >>> The dropper was originally in the mains lead but had been replaced with   
   >>> a component in the case.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)