# What is this part?
**URL:** https://boards.straightdope.com/t/what-is-this-part/706366
**Category:** Factual Questions
**Created:** [December 5, 2014, 12:51am UTC](https://boards.straightdope.com/t/what-is-this-part/706366 "2014-12-05T00:51:11Z")
**Posts on this page:** 10
**Page:** 1
### Author:  [@yearofglad](https://boards.straightdope.com/u/yearofglad)
#### Post date: [December 5, 2014, 12:51am UTC](https://boards.straightdope.com/t/what-is-this-part/706366/1 "2014-12-05T00:51:11Z")
Cleaning out the garage of the previous owner’s stuff and found this thing:
[http://www.yearofglad.com/images/part.jpg](http://www.yearofglad.com/images/part.jpg)
Picture is out of focus because my camera thought I was taking a picture of the box flattened on the coffee table instead of, you know, the big black piece of plastic.
Top has +/- for electrical connections; says “Use with External Resistor”, pretty heavy, about 6 inches tall.
Probably something really obvious to someone who isn’t me.
Thanks in advance.
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### Author:  [@zoltar7](https://boards.straightdope.com/u/zoltar7)
#### Post date: [December 5, 2014, 12:57am UTC](https://boards.straightdope.com/t/what-is-this-part/706366/2 "2014-12-05T00:57:17Z")
Automotive ignition coil. Here’s an ebay listing for a similar part: [http://www.ebay.com/itm/111506461512](http://www.ebay.com/itm/111506461512)
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### Author:  [@yearofglad](https://boards.straightdope.com/u/yearofglad)
#### Post date: [December 5, 2014, 12:57am UTC](https://boards.straightdope.com/t/what-is-this-part/706366/3 "2014-12-05T00:57:20Z")
Missed edit window:
Okay, so I guess it’s an ignition coil.
Does it have any value and, if so, how could I test it to make sure it works before selling it? I’m pretty clueless about these kinds of things.
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### Author:  [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)
#### Post date: [December 5, 2014, 1:00am UTC](https://boards.straightdope.com/t/what-is-this-part/706366/4 "2014-12-05T01:00:12Z")
It’s an automobile ignition coil.
EDIT: Took too long searching for an image. Beat to the answer, and beaten with an image.
.
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### Author:  [@Dag\_Otto](https://boards.straightdope.com/u/Dag_Otto)
#### Post date: [December 5, 2014, 5:10am UTC](https://boards.straightdope.com/t/what-is-this-part/706366/5 "2014-12-05T05:10:10Z")
If you look closely, it says “since 1920”.
You can see where I’m going with this…
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### Author:  [@usedtobe](https://boards.straightdope.com/u/usedtobe)
#### Post date: [December 5, 2014, 7:15am UTC](https://boards.straightdope.com/t/what-is-this-part/706366/6 "2014-12-05T07:15:54Z")
+1 to “things the kids will never know”…
Was a time when any 12 or older boy would instantly recognize it.
It mounts to the firewall - the large coupling is for the wire to the distributor, which then decides which plug gets that particular spark.
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### Author:  [@48Willys](https://boards.straightdope.com/u/48Willys)
#### Post date: [December 5, 2014, 8:19am UTC](https://boards.straightdope.com/t/what-is-this-part/706366/7 "2014-12-05T08:19:37Z")
Once you said “Top has +/- for electrical connections; says “Use with External Resistor”, pretty heavy, about 6 inches tall.” I knew what it was. I did not look at the picture.
Pretty much, you will need to take it to a parts store, or a repair garage to find someone with the machine to test it. I would just replace the one in my truck with yours & try to start it, if the truck runs & drives OK for 30 minutes, it is good. Around here, they go for about $10.00 used.
IHTH, 48.
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### Author:  [@bob\_2](https://boards.straightdope.com/u/bob_2)
#### Post date: [December 5, 2014, 11:25am UTC](https://boards.straightdope.com/t/what-is-this-part/706366/8 "2014-12-05T11:25:00Z")
You could use it to make an electric fence: [A Homemade Electric Fence Charger – Mother Earth News](http://www.motherearthnews.com/diy/homemade-electric-fence-charger-zmaz82jazgoe.aspx#axzz3L1OrFcKm)
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### Author:  [@yearofglad](https://boards.straightdope.com/u/yearofglad)
#### Post date: [December 5, 2014, 3:32pm UTC](https://boards.straightdope.com/t/what-is-this-part/706366/9 "2014-12-05T15:32:47Z")
Thanks for everyone’s help; I don’t have much use for it but will stow it away somewhere, I suppose, since it isn’t worth selling online.
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### Author:  [@Inigo\_Montoya](https://boards.straightdope.com/u/Inigo_Montoya)
#### Post date: [December 5, 2014, 3:43pm UTC](https://boards.straightdope.com/t/what-is-this-part/706366/10 "2014-12-05T15:43:24Z")
> [@Dag\_Otto](#):
>
> If you look closely, it says “since 1920”.
>
> You can see where I’m going with this…
OK, that sent me to the quarry for a few minutes, thanks fot that. 🙂