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Vintage Radio (domestic) Domestic vintage radio (wireless) receivers only. |
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11th Jun 2021, 7:54 am | #1 |
Pentode
Join Date: Jan 2014
Location: Cape Town, South Africa
Posts: 214
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Selenium Rectifier Globe (Lamp) Query
The globe in the pic attached is in series with the mains HT AC side of the rectifier, and gradually starts to glow after switch on to give the valve heaters time to get up to temp.
Can someone enlighten me on the type of globe used? The voltage drop across the globe reaches 2,7 - 2,9V. |
11th Jun 2021, 8:31 am | #2 |
Heptode
Join Date: Mar 2017
Location: Romsey, Hampshire, UK.
Posts: 511
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Re: Selenium Rectifier Globe Query
Hi
Difficult to be sure, but it looks like a miniature bayonet cap light bulb, the sort that would be used for old fashioned torches or radio dial illumination. Assuming that it doesn't glow at full brightness, it could be rated at 6 volts 0.3 amps, but that's only a guess. Looks like a retrofit. |
11th Jun 2021, 8:59 am | #3 |
Dekatron
Join Date: Sep 2006
Location: Kilmarnock, Ayrshire, UK.
Posts: 5,420
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Re: Selenium Rectifier Globe Query
Probably used as a fuse.
I'd say a 100ma bulb, if an HT short occurs or fault in the rectifier it would blow. Definitely a retro fit.
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11th Jun 2021, 10:22 am | #4 |
Dekatron
Join Date: Feb 2007
Location: Leominster, Herefordshire, UK.
Posts: 16,528
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Re: Selenium Rectifier Globe Query
Are the bulb's (globe's) ratings not marked on its metal base?
They may be somewhat difficult to read- a bright light and magnifying glass are handy!
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11th Jun 2021, 11:44 am | #5 |
Pentode
Join Date: Jan 2014
Location: Cape Town, South Africa
Posts: 214
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Re: Selenium Rectifier Globe Query
The globe has GE 57 and what appears to be CANADA printed on it. If it were a regular globe wouldn't it glow at its full brightness on switch on? It takes about 5 - 10 sec to warm up.
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11th Jun 2021, 11:52 am | #6 |
Dekatron
Join Date: Apr 2011
Location: Cornwall, UK.
Posts: 13,454
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Re: Selenium Rectifier Globe Query
At switch on the valves take time to pass sufficient current to illuminate the bulb.
Lawrence. |
11th Jun 2021, 11:53 am | #7 | |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,824
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Re: Selenium Rectifier Globe Query
Quote:
It will only start to light once the valves start to draw HT. In the US they often numbered small lamps rather than putting their ratting on the lamp itself. Haven't had time to check but I think a 57 is a 14V 3.3W MBC Cheers Mike T
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11th Jun 2021, 12:48 pm | #8 |
Pentode
Join Date: Jan 2014
Location: Cape Town, South Africa
Posts: 214
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Re: Selenium Rectifier Globe Query
Great. Thanks for the feedback.
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11th Jun 2021, 8:25 pm | #9 |
Moderator
Join Date: Dec 2010
Location: Exeter, Devon and Poole, Dorset UK.
Posts: 6,824
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Re: Selenium Rectifier Globe Query
OK finally remembered where to find the list of US lamp types.
Hopefully the link will work for non members https://www.radiomuseum.org/forumdata/upload/lamp1.png Cheers Mike T
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Invisible airwaves crackle with life or at least they used to Mike T BVWS member. www.cossor.co.uk |