Hi all,
I have a quick question I was wondering if someone might be able to
answer. What is the standard light bulb number for the 5V lamps in a
Heathkit GC-1195/1197 clock. They are 5V miniature wedge type light
bulbs that are used for the display segments. I guess this could be a
proprietary Heathkit part, but I was hoping maybe someone had changed
these and maybe knew if there was a standard bulb equivalent (the
Heathkit part number is 412-621. Thanks and I do appreciate any help.

Ralph Farr

What you should do is see if you can get a Newark or equivalent catalogue
and carefully go through it. There are hundreds of different types of these
small lamps. I am sure that your lamps are of some standard. I doubt very
much that Heath had their own made, especially in the time that they were
around.

If there are any electronic suppliers in your area, which you can check to
verify in your yellow pages, pay them a visit with a sample of a lamp. You
can try Radio Shack, or a TV service place, but these would be very limited.

If you know the voltage and current rating of the lamp, you can probably
substitute it and also install new sockets to match. This is too much of a
hassle for something that is standard.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
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"Ralph Farr" wrote in message
...
Hi all,
I have a quick question I was wondering if someone might be able to
answer. What is the standard light bulb number for the 5V lamps in a
Heathkit GC-1195/1197 clock. They are 5V miniature wedge type light
bulbs that are used for the display segments. I guess this could be a
proprietary Heathkit part, but I was hoping maybe someone had changed
these and maybe knew if there was a standard bulb equivalent (the
Heathkit part number is 412-621. Thanks and I do appreciate any help.

Ralph Farr

They sound like a standard wedge base 5v lamp. Can you scan or photo this,
and I will match.
Kim
"Ralph Farr" wrote in message
...
Hi all,
I have a quick question I was wondering if someone might be able to
answer. What is the standard light bulb number for the 5V lamps in a
Heathkit GC-1195/1197 clock. They are 5V miniature wedge type light
bulbs that are used for the display segments. I guess this could be a
proprietary Heathkit part, but I was hoping maybe someone had changed
these and maybe knew if there was a standard bulb equivalent (the
Heathkit part number is 412-621. Thanks and I do appreciate any help.

Ralph Farr

Ralph Farr wrote in message ...
Hi all,
I have a quick question I was wondering if someone might be able to
answer. What is the standard light bulb number for the 5V lamps in a
Heathkit GC-1195/1197 clock. They are 5V miniature wedge type light
bulbs that are used for the display segments. I guess this could be a
proprietary Heathkit part, but I was hoping maybe someone had changed
these and maybe knew if there was a standard bulb equivalent (the
Heathkit part number is 412-621. Thanks and I do appreciate any help.

Ralph Farr

Hi Ralf,

I built one of those clocks a long time ago and it is currently
lounging on my "to play with" pile. It was a great conversation piece,
and always drew comments.

Those little bulbs are problematic. I've had the clock for years and
they get loose in the socket, or burn out at different times. I'm
planning on replacing them with high brightness L.E.D.'s. You could
measure the lamp voltage with the photocell light (I think I remember
the intensity increasing with room light) and calculate an appropriate
value of series resistance for the LED. Glue it into the segment,
wire it to the board with soldered connections and you are done for
probably a few decades. I did illuminate a segment red, and it looked
great (keep the LED at the back of the bulb hole so the segment can
spread the light). I'd love to see it in blue, but then you get pretty
expensive.

Illuminate a segment for yourself with a LED before you commit to
hacking it up. If you use multiple LEDs per segment, I'm sure you can
make the thing overly bright.

As I said, it is waiting for me to try and I have no final report. For
me, if it doesn't work out, I'll trash the clock anyway. I'm done
playing bulb-boy.

That clock used to throw off some warmth from the linear regulator.
This should save some power as well.

Now, if you could only add the "atomic clock" circuit so the thing
sets its own time on power outage...

Good Luck,

Jim

In article ,
says...
Ralph Farr wrote in message ...
Hi all,
I have a quick question I was wondering if someone might be able to
answer. What is the standard light bulb number for the 5V lamps in a
Heathkit GC-1195/1197 clock. They are 5V miniature wedge type light
bulbs that are used for the display segments. I guess this could be a
proprietary Heathkit part, but I was hoping maybe someone had changed
these and maybe knew if there was a standard bulb equivalent (the
Heathkit part number is 412-621. Thanks and I do appreciate any help.

Ralph Farr

Hi Ralf,

I built one of those clocks a long time ago and it is currently
lounging on my "to play with" pile. It was a great conversation piece,
and always drew comments.

Those little bulbs are problematic. I've had the clock for years and
they get loose in the socket, or burn out at different times. I'm
planning on replacing them with high brightness L.E.D.'s. You could
measure the lamp voltage with the photocell light (I think I remember
the intensity increasing with room light) and calculate an appropriate
value of series resistance for the LED. Glue it into the segment,
wire it to the board with soldered connections and you are done for
probably a few decades. I did illuminate a segment red, and it looked
great (keep the LED at the back of the bulb hole so the segment can
spread the light). I'd love to see it in blue, but then you get pretty
expensive.

Illuminate a segment for yourself with a LED before you commit to
hacking it up. If you use multiple LEDs per segment, I'm sure you can
make the thing overly bright.

As I said, it is waiting for me to try and I have no final report. For
me, if it doesn't work out, I'll trash the clock anyway. I'm done
playing bulb-boy.

That clock used to throw off some warmth from the linear regulator.
This should save some power as well.

Now, if you could only add the "atomic clock" circuit so the thing
sets its own time on power outage...

Good Luck,

Jim

Thanks for your reply Jim - I had never thought about using LED's but
that is something I would definitely consider now.

Ralph

Thanks for your reply Jim - I had never thought about using LED's but
that is something I would definitely consider now.

Ralph

Seems it would kinda lose some of it's vintage charm if you did that,
incandescent segments are something you don't see much these days.

Yeah, and the reason you don't SEE many of them any more is that they keep
burning out!

Perhaps the way to keep the vintage stuff original would be to put a small
value resistor in series with the bulbs so they last longer. They'd be
dimmer, but put it on a shelf near the ceiling where it's darker anyway and
maybe no one will notice.

Bob M.
======
"James Sweet" wrote in message
news:[email protected]_s03...


Thanks for your reply Jim - I had never thought about using LED's but
that is something I would definitely consider now.

Ralph

Seems it would kinda lose some of it's vintage charm if you did that,
incandescent segments are something you don't see much these days.

"Bob M." wrote in message
...
Yeah, and the reason you don't SEE many of them any more is that they keep
burning out!

Perhaps the way to keep the vintage stuff original would be to put a small
value resistor in series with the bulbs so they last longer. They'd be
dimmer, but put it on a shelf near the ceiling where it's darker anyway
and
maybe no one will notice.

Bob M.

Well yeah, I didn't say incandecent was very practical, but it's cool none
the less. Someone else mentioned this unit has a photocell to dim it when
the room is dark, one could probably just put a variable resistor across or
in series with this to adjust the max brightness, dimming it 20% would
extend lamp life considerably, but then if you get a large quantity of
replacement lamps it'd be pretty easy to just replace them when they burn
out, or group relamp the segments that see the most use.

Hi

You can go a long way to drive the life of the bulb up with two
resistors. Put one resistor in series with the bulb to knock down the
applied voltage. The other resistor is put in parallel across the switch
to put just a little current through the filament when it is supposed to
be off. It should just glow faint red. By doing this, the inrush current
is reduced since the filament is already hot. Inrush current is what
kills the bulbs.

Regards





"James Sweet" wrote in
news:[email protected]_s03:


"Bob M." wrote in message
...
Yeah, and the reason you don't SEE many of them any more is that they
keep burning out!

Perhaps the way to keep the vintage stuff original would be to put a
small value resistor in series with the bulbs so they last longer.
They'd be dimmer, but put it on a shelf near the ceiling where it's
darker anyway
and
maybe no one will notice.

Bob M.

Well yeah, I didn't say incandecent was very practical, but it's cool
none the less. Someone else mentioned this unit has a photocell to dim
it when the room is dark, one could probably just put a variable
resistor across or in series with this to adjust the max brightness,
dimming it 20% would extend lamp life considerably, but then if you
get a large quantity of replacement lamps it'd be pretty easy to just
replace them when they burn out, or group relamp the segments that see
the most use.

Ralph Farr wrote in message

Thanks for your reply Jim - I had never thought about using LED's but
that is something I would definitely consider now.

Ralph

Sorry on the mis-type of your name.

The control chip is, apparently, National MM5387AA/N

Can't vouch for the source, but here you go:
http://www.chipdocs.com/pndecoder/da...MM5387AAN.html

Jim