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ms660 · 2nd Dec 2019, 10:21 pm

I would have thought that was about right, especially for the one across the scale lamps, as that one only has any significant purpose when any of the scale lamps go open circuit, if you do the ohms law for their respective hot values given in the schematic you will find that everything tallies up voltage drop wise for the dropper resistors and heater string for the mains voltage selected (the resistance given for the one across the scale lamps being the hot resistance with one or both of the scale lamps open circuit)

For instance look at the hot and cold resistances for the VA1009, VA1010, VA1011 etc here for 100mA series heater chains:

http://www.electrojumble.org/DATA/Mu...o%20VA1040.pdf

Lawrence.

2nd Dec 2019, 10:21 pm	#15
ms660 Dekatron Join Date: Apr 2011 Location: Cornwall, UK. Posts: 13,454	Re: Philetta BD 244U I would have thought that was about right, especially for the one across the scale lamps, as that one only has any significant purpose when any of the scale lamps go open circuit, if you do the ohms law for their respective hot values given in the schematic you will find that everything tallies up voltage drop wise for the dropper resistors and heater string for the mains voltage selected (the resistance given for the one across the scale lamps being the hot resistance with one or both of the scale lamps open circuit) For instance look at the hot and cold resistances for the VA1009, VA1010, VA1011 etc here for 100mA series heater chains: http://www.electrojumble.org/DATA/Mu...o%20VA1040.pdf Lawrence.