Grain-of-wheat bulbs

  • Thread starter Paul Hovnanian P.E.
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Paul Hovnanian P.E.

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I'm looking for a couple of these to repair some (antique) equipment. They
should be 1.5V, about 30mA and produce a relatively 'white' light at this
current. Some Radio Shack 6V, 100mA bulbs draw approximately the correct
current at 1.5V, but they are too reddish and dim to be of any use.

These are used in an old photographic light meter as a null indicator. LEDs
won't work at this voltage level (too dim and no where near linear
brightness vs voltage).

--
Paul Hovnanian paul@hovnanian.com
----------------------------------------------------------------------
Have gnu, will travel.
 
In article <Noadne83-tm2XszRnZ2dnUVZ_sKdnZ2d@posted.isomediainc>,
Paul Hovnanian P.E. <paul@hovnanian.com> wrote:

I'm looking for a couple of these to repair some (antique) equipment. They
should be 1.5V, about 30mA and produce a relatively 'white' light at this
current. Some Radio Shack 6V, 100mA bulbs draw approximately the correct
current at 1.5V, but they are too reddish and dim to be of any use.

These are used in an old photographic light meter as a null indicator. LEDs
won't work at this voltage level (too dim and no where near linear
brightness vs voltage).
Click to expand...
First Googling turns up some bulbs offered by Kit Kraft, for dollhouse
use: http://www.kitkraft.biz/product.php?productid=5582

Stated as 1.5 - 3 volts, current draw not stated.

--
Dave Platt <dplatt@radagast.org> AE6EO
Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior
I do _not_ wish to receive unsolicited commercial email, and I will
boycott any company which has the gall to send me such ads!
 
On Thu, 29 Jul 2010 11:07:21 -0700, "Paul Hovnanian P.E." wrote:

I'm looking for a couple of these to repair some (antique) equipment. They
should be 1.5V, about 30mA and produce a relatively 'white' light at this
current.
Click to expand...
You could cannibalize a cheap LCD watch. They use tiny 1.5V bulbs to
backlit the display.

Piotr
 
On Thu, 29 Jul 2010 11:07:21 -0700, "Paul Hovnanian P.E." <paul@hovnanian.com> wrote:

I'm looking for a couple of these to repair some (antique) equipment. They
should be 1.5V, about 30mA and produce a relatively 'white' light at this
current. Some Radio Shack 6V, 100mA bulbs draw approximately the correct
current at 1.5V, but they are too reddish and dim to be of any use.

These are used in an old photographic light meter as a null indicator. LEDs
won't work at this voltage level (too dim and no where near linear
brightness vs voltage).
Click to expand...
If you could add an opamp for voltage to current, you might be able to
use a LED. Otherwise more shopping around, perhaps hobby model shops?

Grant.
 
On 7/29/2010 2:07 PM, Paul Hovnanian P.E. wrote:
I'm looking for a couple of these to repair some (antique) equipment. They
should be 1.5V, about 30mA and produce a relatively 'white' light at this
current. Some Radio Shack 6V, 100mA bulbs draw approximately the correct
current at 1.5V, but they are too reddish and dim to be of any use.

These are used in an old photographic light meter as a null indicator. LEDs
won't work at this voltage level (too dim and no where near linear
brightness vs voltage).
Click to expand...
Ebay #> 120598027723

Have to hack the cute lampshades off maybe?
JC
 
On 7/29/2010 7:05 PM, Archon wrote:
On 7/29/2010 2:07 PM, Paul Hovnanian P.E. wrote:
I'm looking for a couple of these to repair some (antique) equipment.
They
should be 1.5V, about 30mA and produce a relatively 'white' light at this
current. Some Radio Shack 6V, 100mA bulbs draw approximately the correct
current at 1.5V, but they are too reddish and dim to be of any use.

These are used in an old photographic light meter as a null indicator.
LEDs
won't work at this voltage level (too dim and no where near linear
brightness vs voltage).


Ebay #> 120598027723

Have to hack the cute lampshades off maybe?
JC
or you could try
Click to expand...

http://www.miniatronics.com/Merchant2/merchant.mvc?Screen=CTGY&Category_Code=1_1

JC
 
On 7/29/2010 11:07 AM Paul Hovnanian P.E. spake thus:

I'm looking for a couple of these to repair some (antique) equipment. They
should be 1.5V, about 30mA and produce a relatively 'white' light at this
current. Some Radio Shack 6V, 100mA bulbs draw approximately the correct
current at 1.5V, but they are too reddish and dim to be of any use.

These are used in an old photographic light meter as a null indicator. LEDs
won't work at this voltage level (too dim and no where near linear
brightness vs voltage).
Click to expand...
Is that meter by any chance a Gossen? the type with two bulbs that light
up equally bright when the dial is adjusted correctly? I had one of
those when I was a kid. Luna Pro?


--
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.

- Comment from an article on Antiwar.com (http://antiwar.com)
 
On Thu, 29 Jul 2010 11:07:21 -0700, the renowned "Paul Hovnanian P.E."
<paul@hovnanian.com> wrote:

I'm looking for a couple of these to repair some (antique) equipment. They
should be 1.5V, about 30mA and produce a relatively 'white' light at this
current. Some Radio Shack 6V, 100mA bulbs draw approximately the correct
current at 1.5V, but they are too reddish and dim to be of any use.

These are used in an old photographic light meter as a null indicator. LEDs
won't work at this voltage level (too dim and no where near linear
brightness vs voltage).
Click to expand...
Try a hobby shop that caters to model railroaders (lots of other
interesting stuff there too!)

Eg.
http://www.grsmicroliting.com/eshop/index.html?target=dept_5.html&lang=en-us
"1.5V and 3.0V Super GOR Bulbs"




Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com
 
In article <Noadne83-tm2XszRnZ2dnUVZ_sKdnZ2d@posted.isomediainc>,
paul@hovnanian.com says...
I'm looking for a couple of these to repair some (antique) equipment. They
should be 1.5V, about 30mA and produce a relatively 'white' light at this
current. Some Radio Shack 6V, 100mA bulbs draw approximately the correct
current at 1.5V, but they are too reddish and dim to be of any use.

These are used in an old photographic light meter as a null indicator. LEDs
won't work at this voltage level (too dim and no where near linear
brightness vs voltage).


www.cir-kitconcepts.com
Click to expand...

--- news://freenews.netfront.net/ - complaints: news@netfront.net ---
 
Paul Hovnanian P.E. wrote:
I'm looking for a couple of these to repair some (antique) equipment. They
should be 1.5V, about 30mA and produce a relatively 'white' light at this
current. Some Radio Shack 6V, 100mA bulbs draw approximately the correct
current at 1.5V, but they are too reddish and dim to be of any use.

These are used in an old photographic light meter as a null indicator. LEDs
won't work at this voltage level (too dim and no where near linear
brightness vs voltage).
Click to expand...
1.5v @ 40 ma. lamp (All Electronics): http://tinyurl.com/24khy9l
....they also carry a 3v @ 55 ma. version.
 
David Nebenzahl wrote:
On 7/29/2010 11:07 AM Paul Hovnanian P.E. spake thus:

I'm looking for a couple of these to repair some (antique) equipment. They
should be 1.5V, about 30mA and produce a relatively 'white' light at this
current. Some Radio Shack 6V, 100mA bulbs draw approximately the correct
current at 1.5V, but they are too reddish and dim to be of any use.

These are used in an old photographic light meter as a null indicator. LEDs
won't work at this voltage level (too dim and no where near linear
brightness vs voltage).

Is that meter by any chance a Gossen? the type with two bulbs that light
up equally bright when the dial is adjusted correctly? I had one of
those when I was a kid. Luna Pro?
Click to expand...
Yes.

One lamp is burned out. I measured the voltage and lamp current of the
good one. I'll be replacing both of them (just to keep the differential
circuit properly balanced).

--
Paul Hovnanian mailto:paul@Hovnanian.com
------------------------------------------------------------------
c (velocity of light in a vacuum) = 1.8x10^12 furlongs per fortnight
 
"Paul Hovnanian P.E." <Paul@Hovnanian.com> wrote in message
news:4C68AE9C.5AFCA9AF@Hovnanian.com...
David Nebenzahl wrote:

On 7/29/2010 11:07 AM Paul Hovnanian P.E. spake thus:

I'm looking for a couple of these to repair some (antique) equipment.
They
should be 1.5V, about 30mA and produce a relatively 'white' light at
this
current. Some Radio Shack 6V, 100mA bulbs draw approximately the
correct
current at 1.5V, but they are too reddish and dim to be of any use.

These are used in an old photographic light meter as a null indicator.
LEDs
won't work at this voltage level (too dim and no where near linear
brightness vs voltage).

Is that meter by any chance a Gossen? the type with two bulbs that light
up equally bright when the dial is adjusted correctly? I had one of
those when I was a kid. Luna Pro?

Yes.

One lamp is burned out. I measured the voltage and lamp current of the
good one. I'll be replacing both of them (just to keep the differential
circuit properly balanced).

--
Paul Hovnanian mailto:paul@Hovnanian.com
------------------------------------------------------------------
c (velocity of light in a vacuum) = 1.8x10^12 furlongs per fortnight
Click to expand...

Model train hobby shops carry all sorts of small lamps. Might give one of
them a try.

Mark Z.
 
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