XPost: alt.home.repair, uk.d-i-y
From: rod.speed.aaa@gmail.com
"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
> 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.
> 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)
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