New Member With Simple (I Hope) Question

Discussion in 'General Electronics Chat' started by Alphonso, Jan 25, 2011.

  1. Alphonso

    Thread Starter New Member

    Jan 25, 2011
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    Howdy all, new member here,

    I have what I hope is a simple question.

    We are refurbishing and old house and I've run into a bit of a problem with the electric "on" light in a 40 year old warming oven. The "on" light is simply a little pilot type of light that glows when the warming oven is on. It shines through a bit of red plastic.

    The light worked, but was out of its holder. While trying to secure it in its holder I shattered the glass bulb. It was a tiny bulb with two solder-on leads. Once the glass was smashed, there was nothing left to identify the type of bulb that it had been. The bulb is/was about 1/8 inch in diameter and about 3/8 inch long.

    The power supply for the bulb is 110 volts with one small component soldered in series with the bulb into one of the supply lines. The component looks like a resistor to me, but I'm not sure. The component is about 3/8 inch long, about 1/8 inch in diameter, and is black with one white band around it.

    "Above" the component I get a 110v reading. "Below" the component I get a 16v reading. I think the 16v reading is also AC current.

    I replaced the shattered bulb with a similar looking 12v bulb from the auto store. It would not light. I checked the bulb with a 9v battery and it lighted fine.

    I removed the component from the power source and wired the 12v bulb directly in. When I hit the power, the bulb went off like a tiny bomb! Having considered that as a possibility, I was wearing safety glasses. :)

    So, I either need to find the correct bulb to replace the one that I shattered, or find another solution to run a small LOW TEMPURATURE bulb from the 110v power supply. A high tempurature bulb would melt the little plastic "jewel" that the light shines through.

    I do not have room for a normal 110v to 12v transformer.

    The warming oven is over 40 years old and I cannot find a soul in my small town who understands how to get from 110v to about 16v with one tiny component and/or what sort of bulb I need.

    Any ideas for me? Thank you in advance for the help...
     
  2. hgmjr

    Moderator

    Jan 28, 2005
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    Can you take a picture of what is left of the original bulb? It sounds like it was a neon bulb.

    hgmjr
     
  3. Alphonso

    Thread Starter New Member

    Jan 25, 2011
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    There is nothing left of the original bulb. It shattered into a zillion pieces. I did not notice if it had a filament...
     
  4. hgmjr

    Moderator

    Jan 28, 2005
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    Can you remember if it looked like any of these bulbs?

    These are examples of neon bulbs.


    hgmjr
     
  5. Alphonso

    Thread Starter New Member

    Jan 25, 2011
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    It is/was shaped most like the third one from the left. I did not notice if it had an internal "filament" structure like the ones shown or if it was an incandescent.

    Given that the bulb could not have run hot without melting the plastic jewel, I think you might be on to the right answer.

    Would a 110v supply with the little resistor-looking component be the right set up to power a florescent bulb?

    Thanks...
     
  6. hgmjr

    Moderator

    Jan 28, 2005
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    Nope. A flourescent bulb needs a fairly complex drive signal to work properly.

    I think a neon bulb is your best bet. It will need a series resistor.

    hgmjr
     
  7. Alphonso

    Thread Starter New Member

    Jan 25, 2011
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    I mistyped the word fluorescent above when I meant to say neon.

    Will 110v with the little component (1/8 diameter, 3/8 in length, black with a white stripe) likely be the series resistor you mention?

    Thank you for this help. I wouldn't have thought of a neon bulb in a zillion years.
     
  8. hgmjr

    Moderator

    Jan 28, 2005
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    A 10K resistor in series with the neon bulb should be fine. You must be very careful when dealing with AC mains. Be very sure that it is unplugged from power outlet before messing with it. Also make sure that there are no exposed bare wires around the bulb before you power the oven back up.

    hgmjr
     
  9. Alphonso

    Thread Starter New Member

    Jan 25, 2011
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    Hgmgr,

    Thank you for your help. I did some web surfing and have found the part I need.

    Also, thanks for the safety reminders. Knowing as little as I do about electricity I am always very very careful to turn everything off before I mess with it.

    I've got a lot done on this old house for a guy that don't hardly know nothing...:)
     
  10. BillB3857

    Senior Member

    Feb 28, 2009
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  11. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Radio Shack sells the NE-2 Bulbs with the resistor already soldered on, so you only need to connect it. Might be slightly cheaper than ordering one from a website, but maybe not.
     
  12. Alphonso

    Thread Starter New Member

    Jan 25, 2011
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    Thanks Gents for all the help. I'll hit RS in the morning and if they don't have it I'll hoof across town to the appliance repair place.

    I found it on line, but I have to order 5 of them to meet the minimum order amount. That, plus shipping, makes a local look-round worth while.

    Nice group of folks here.
     
  13. Audioguru

    New Member

    Dec 20, 2007
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    No, and be careful.
    An NE-2 neon bulb like the one the OP said it looked like uses a 150k or 180k resistor on a 120VAC circuit. It might blow up or the resistor might blow up if it is only 10k.
     
  14. hgmjr

    Moderator

    Jan 28, 2005
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    Yeah. Looks like 10K is definitely a bit on the low side. At least it would be bright for a brief moment.

    hgmjr
     
  15. Audioguru

    New Member

    Dec 20, 2007
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    Post a video of your neon bulb blowing up because its resistor value is way too low.

    RadioShack is gone from my part of Canada because they had no technical people (just salesmen selling cell phones) and their prices for poor quality parts were way higher than anybody else.
    I think their electronic parts are and were "seconds" that failed tests.

    I bought a video cable at RadioShack then found exactly the same one at The Dollar Store for much less cost. I bought the one at The Dollar Store and returned it to RadioCrap for my money back.
     
  16. hgmjr

    Moderator

    Jan 28, 2005
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    Greetings Alphonso,

    I agree with Audioguru. Let's take the current down an order of magnitude and use a 100K rather than 10K. That way we can avoid any possibility of destruction to your NE-2 neon lamp.

    hgmjr
     
  17. Alphonso

    Thread Starter New Member

    Jan 25, 2011
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    Thanks to all. I found the neon light at RS for $1.50. I removed the bulb from the cheesy red plastic cover and it fit and functions just fine.

    Now when our warming oven is on we have a nice little red glowing light to remind us...
     
  18. magnet18

    Senior Member

    Dec 22, 2010
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    Sounds just like the northeastern Indiana RadioShacks I love to hate. :p :mad:
     
  19. soda

    Active Member

    Dec 7, 2008
    174
    13
    Why don't you just buy a complete neon bulp with a resistor soldered to it.
    You'll be able to get it in any electrical store.

    Just tell them the name of the oven and the voltage it's using. I'm sure these guys would be able to help you.

    This is anyway how it work down here is SA.It is as simple as eating bread [​IMG]
     
  20. hgmjr

    Moderator

    Jan 28, 2005
    9,030
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    That is terrific. So glad to hear you have accomplished your goal of getting the indicator back up and running.

    hgmjr
     
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