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Philips Historische Producten museum Eindhoven (51/52) In the early 1900s Philips expanded its business beyond (incandescent) lamps and lighting. Following early works on gas discharges at the company's NatLab in Eindhoven, it began producing various electrical devices for the radio and the electrotechnical industry. A good example of this is the gas-filled diode shown here, which formed the basis of later low-pressure mercury and sodium lamps. Keywords: Miscellaneous

Philips Historische Producten museum Eindhoven (51/52)


In the early 1900s Philips expanded its business beyond (incandescent) lamps and lighting. Following early works on gas discharges at the company's NatLab in Eindhoven, it began producing various electrical devices for the radio and the electrotechnical industry. A good example of this is the gas-filled diode shown here, which formed the basis of later low-pressure mercury and sodium lamps.
_IMG0287.JPG _IMG0288.JPG _IMG0289.JPG _IMG0292.JPG WC-C150S55-D-40-1.jpg
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Filename:_IMG0289.JPG
Album name:Max / Places and displays
Keywords:Miscellaneous
Filesize:1298 KiB
Date added:30 May 2026
Dimensions:1800 x 1200 pixels
Displayed:88 times
DateTime Original:2016:08:23 14:20:28
URL:https://trad-lighting.net/gallery/displayimage.php?pid=1293
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Comment 1 to 3 of 3
Page: 1

Drew   [Sun 31 May 2026 at 01:01]
What an interesting device, looks just like a mercury arc rectifier (the kind with the mercury pool), but it has an oxide cathode. I assume the long electrode arms on these devices are mainly there to increase the maximum reverse voltage?
Max   [Sun 31 May 2026 at 07:23]
Your assumption is correct. The anodes are placed far away from the central cathode to prevent reverse ignition at a too low voltage. Another interesting detail is the aquadag strip painted on each leg. I think those play the dual roles of preventing reverse ignition by homogenizing the electric field around the side electrodes when they are at negative potential, while facilitating forward ignition via a capacitive influence with the central electrode. It's a very interesting design!
Drew   [Sun 31 May 2026 at 20:54]
Very interesting, I have also seen pool-style mercury arc rectifiers that had anode arms completely covered with aquadag (or as completely as is expected for a device many decades old). Cool to know!

Comment 1 to 3 of 3
Page: 1