[BC] 110 V DC AC/DC radios 5 tube all american

[Harold Hallikainen]

> I worked at a Radio Station where they had a AC/DC TV set and they had put
>  a
> jack on the speaker so they could tape audio.  In several previous
> incidents
> I even placed an isolation transformer the audio line to reduce  to
> potential
> hazard.
>
> Most of these types of  receiver sets are now gone away and most gear
> uses a
> power transformer. Some transmitters even use a transformer just for
> isolation.  For example our last AM product line used 220 VAC single phase
>  and three
> phase. In any case we could have rectified the line coltage directly  and
> filtered the ripple as the voltage used was around 210 VAC.  The use of
> transformers elminated the potential of ground loops and provided taps for
>  voltage
> ranges from 190 to 250 VAC.  Several companies are now using  switching
> techniques and using AC  direct with no transformers.
>
> Dave


I designed a one-off battery charger for an electric car. It had 11 12V
lead acid batteries. The charger consisted of an SCR and a series light
bulb for each phase of a 3 phase wye line. The SCR did rectification and
allowed us to turn off the charger when the battery string was charged.
The light bulb acted as a ballast current limit, so we charged with a
voltage limited constant current source. If 3 phase power was not
available, single phase 120VAC or 240VAC could be used. The neutral went
to the negative side of the battery. The battery string is isolated from
the body of the car. So, it was transformer isolated, but we let the power
company provide the transformer...

Harold


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