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 2.5 volt dial light bulbs
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 Return to top of page · Post #: 1 · Written at 9:04:54 AM on 7 September 2020.
Simplex's Gravatar
 Location: Bathurst, NSW
 Member since 7 August 2008
 Member #: 336
 Postcount: 342

Putting the finishing touches to a 1930's floor stander radio which I have mentioned in another thread. Has the 57/58/55 2.5v valve lineup and the original dial bulb runs of the heater supply.

The original bulb has long blown and been putting in 2.5v torch bulbs but they do not last long as guess torch bulbs not meant for continuous duty.

By chance would the be a supplier whom has 2.5v edison screw bulbs about, perhaps a stash of NOS bulbs ?

Incandescent bulbs are getting hard to find nowadays. LED's give a horrible blueish light and I avoid the LED path.

Thanks for any help with this.


 
 Return to top of page · Post #: 2 · Written at 9:46:06 AM on 7 September 2020.
Johnny's avatar
 Location: Hobart, TAS
 Member since 31 July 2016
 Member #: 1959
 Postcount: 429

The automotive supplies would probably have old stock of the miniature interior light fittings.
So, perhaps we may have to resort to say an old plugpack transformer hidden within the chassis and a separate dial light circuit.
With the right voltage choices they could potentially (globes) last for a very long time.
JJ


 
 Return to top of page · Post #: 3 · Written at 9:50:50 AM on 7 September 2020.
Jimb's Gravatar
 Location: Kanahooka, NSW
 Member since 18 November 2016
 Member #: 2012
 Postcount: 710

I think I have some. I will check later. I have one in my 1934 STC model 55 I think and it is lasting well.


 
 Return to top of page · Post #: 4 · Written at 11:21:09 AM on 7 September 2020.
Robbbert's avatar
 Location: Sydney, NSW
 Member since 18 September 2015
 Member #: 1801
 Postcount: 1464

My oldest radio uses those bulbs, but they kept blowing so I switched over to 3.5 volt bulb, works great.

Last time I looked (a few years ago), both were available at Jaycar.


 
 Return to top of page · Post #: 5 · Written at 11:31:32 AM on 7 September 2020.
Simplex's Gravatar
 Location: Bathurst, NSW
 Member since 7 August 2008
 Member #: 336
 Postcount: 342

Yes 3.5's were suggested by a fellow collector and have a few but want to hang onto them for old torches I have.

Trouble is the day of the incandescent bulb is over and not sure Jaycar is now even selling torch bulbs of any sort.

Will have a look online.

Thanks

EDIT: just looked at Jaycar, they have a 4.8v krypton bulb which may do. A new store has opened up at Orange so will pay a visit.

As before there are very few incandescent bulbs about nowadays.

Thanks for the tip re Wagner, forgot about them.


 
 Return to top of page · Post #: 6 · Written at 11:35:00 AM on 7 September 2020.
GTC's avatar
 GTC
 Location: Sydney, NSW
 Member since 28 January 2011
 Member #: 823
 Postcount: 6142

Check also Wagner. They keep a pretty diverse stock of parts: https://www.wagneronline.com.au/


 
 Return to top of page · Post #: 7 · Written at 12:49:56 PM on 8 October 2020.
Keith Walters's avatar
 Location: Sydney, NSW
 Member since 16 January 2008
 Member #: 219
 Postcount: 56

We still sell 2.5V MES bulbs at Jaycar, but I can't see where we ever sold a 3.5V type. Either that pre-dates the current record keeping system, or it might have been Dick Smith you're thinking of.

Actually we shift over 7,000 SL3210 a year, (actually 14,000 bulbs as they come in a pack of 2) as they're still widely used in kids' school projects.

https://www.jaycar.com.au/2-5v-screw-in-type-globe/p/SL3210

Also about as many of the "breadboard"sockets:

https://www.jaycar.com.au/bakelite-mes-globe-holder/p/SL2659

As for service life, basically, "they are what they are."
Some popular items are getting almost impossible to obtain now, and we have to take what we can get.
I suppose for a kids' school projects a short operating life isn't a big issue. For radio use I can only suggest you do a "burn-in" before actually fitting to the radio.

Incidentally, we also sell huge numbers of SL2654 annually, the 6.3V type.


 
 Return to top of page · Post #: 8 · Written at 12:00:33 AM on 9 October 2020.
Marcc's avatar
 Location: Wangaratta, VIC
 Member since 21 February 2009
 Member #: 438
 Postcount: 4460

Note that there are two types of 6.3V types. The long envelope one at around 300mA and a smaller round envelope & around half the current draw. These are the ones that don't burn holes in the dial plastic of "Empire States" & a few others.


 
 Return to top of page · Post #: 9 · Written at 1:35:01 AM on 9 October 2020.
Tallar Carl's avatar
 Location: Latham, ACT
 Member since 21 February 2015
 Member #: 1705
 Postcount: 1594

Simplex I believe I might have some 2.5s here in my stack. If you see this send me a email reminder and I will look for them and you can have them. I have a box full.


 
 Return to top of page · Post #: 10 · Written at 7:27:47 AM on 26 June 2021.
Wa2ise's avatar
 Location: Oradell, US
 Member since 2 April 2010
 Member #: 643
 Postcount: 772

You could insert in series a resistor or diode to cut the effective voltage on the bulbs. Which should make them last much longer.


 
 Return to top of page · Post #: 11 · Written at 11:45:20 AM on 26 June 2021.
Brad's avatar
 Administrator
 Location: Greenwich, NSW
 Member since 15 November 2005
 Member #: 1
 Postcount: 6532

I'd be careful going too high with the voltage rating. The higher the working voltage of a globe, the lower the resistance may be and you could get to the stage of creating a short in the circuit. WA2ISE's suggestion of a diode in series with the globe may do the trick. A 1N4001 in series will give a voltage drop of 0.6V and cost next to nothing and Jaycar will have boxes of them. If a slightly less intense glow from the globe isn't an issue, this should see it last a lot longer.

The only LED globes that are suitable for vintage radios are warm white but retailers absurdly believe that everyone wants the harsher daylight colour temperature and this is not the case. 3000K is perfect for radios.

Do some reading on any LED globes you buy. They may be expecting DC and most radio globe holders supply AC to the globe. In such cases, the best you'll get is a globe that flickers at the mains frequency. At worst, the driver may want to go on strike.


‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾‾
A valve a day keeps the transistor away...

 
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