Heath product with 120/240 slide switch instead of diff.wiring

[Heinz und Hannelore Breuer]

Hi,

Brian is correct that a lot of gear (HP, Fluke, Tektronix etc) is
switchable and these units usually have a detachable power cord and here
is where Marshall's posting makes sense about different kind of power
plugs used for 110V and 220V. However there are always exeptions from
the rule: I had a O-12 scope sold in Germany by Daystrom (Heath) which
had a fixed power cord and required changing the connector to get it on 110V.
.
Murray wanted a schematic where a DPDT switch is used for switching:

                           •
    o-----|-----------------II
          |                 II
          |         a       II
       |--)---------o       II    primary 1
       |  |                 II      110V
       |  |   |----o==o-----II
       |  |   |    b
       |  |   |
       |  |   |    a
       |  |---)----o
       |      |            •
       |      |---o==o------II
       |          b         II
       |                    II
       |                    II    primary 2
       |                    II       110V
     o----------------------II

Switch in settind a: primaries parallel = 110V
Switch in setting b: primaries in series = 220V

Just observe the polarity of the primary windings or it will not work.

73
de Heinz DH2FA, KM5VT



Brian Carling wrote:
>
> On 1 Sep 2002 at 23:06, Marshall wrote:
>
> > Hello, Murray and Group,
> >
> > The reason you don't see equipment switched for 120/240 volts is
> > two-fold:
> >         1. 120 volt line cord plugs are different from 240 volt plugs.
> >            Look at your toaster, and then your electric clothes dryer!
> >
> >         2. If this switch was set for 240 volts and assuming you could
> >            plug it into 120 volts, the secondary voltage would only be
> >            one half of what it was when selected for 240 volts, BUT...
> >            if the switch was set for 120 volts and you were able to
> >            plug it into 240 volts, the secondary winding would be
> >            TWICE as much, and that would absolutely ruin your day.
> >
> > Marshall M. Dues - WB5MYO
> > Katy, Texas
>
> Hmmmm... strange, but a LOT of gear is switchable for 1115 and 230 Volts. Many
> power supplies, commercial, ham, medical etc.
>
> I don't know about the older Heath gear because none is sitting on my bench at
> present, but there is NO reason why they could not have made them switchable.
>
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