17-09-2015, 06:41 PM
Hi Nick, that is the Philips "simple" voltage selector. They normally don't do anything simply at Philips.
There is another type that has at least 2 links on the selector and there are 2, primaries, each rated for about 130v these can be series and parallel connected for voltages from 100 to 250 py various positions of the voltage selector.
Complicated, but all down to economics of transformer production for various countries/ voltages worldwide.
The technique mentioned earlier of feeding a low voltage into the heater windings will work very well to ID windings. This works best when the valves that were used with the particular transformer are known.
Note that sec windings often had "compensating " turns to overcome losses in the transformer, so a 4v winding, when used as an input may need 4.5 v to get the correct output on another winding.
Ed
There is another type that has at least 2 links on the selector and there are 2, primaries, each rated for about 130v these can be series and parallel connected for voltages from 100 to 250 py various positions of the voltage selector.
Complicated, but all down to economics of transformer production for various countries/ voltages worldwide.
The technique mentioned earlier of feeding a low voltage into the heater windings will work very well to ID windings. This works best when the valves that were used with the particular transformer are known.
Note that sec windings often had "compensating " turns to overcome losses in the transformer, so a 4v winding, when used as an input may need 4.5 v to get the correct output on another winding.
Ed
