Quad Comparator Pins

DIY timing systems
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Kurt Wylde
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Quad Comparator Pins

Post by Kurt Wylde »

Hello
How can I determine the pin numbering on these chips? The packaging didn't explain anything. I am building the circuit from the plans on this website, 4 lane version.

Thanks!
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gpraceman
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Re: Quad Comparator Pins

Post by gpraceman »

Where did you get the quad comparators from? What brand are they?

You may be able to find a spec sheet for them on the website for the supplier or the manufacturer.
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Stan Pope
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Re: Quad Comparator Pins

Post by Stan Pope »

One corner pin (in a DIP package) should be distinguished by a mark on the top of the body, usually (in my distant experience) a circular indentation. This is pin #1. Numbering progresses sequentially along that side of the body, jumps across the body, and continues back toward the original end.

Sometimes only the #1 end of the DIP package is identified by a semicircular indentation in the top of the body. Since I am dexlistic (or is it dislexic?), I won't try to tell you from memory whether numbering (as viewed from the top of the body) is clockwise or counterclockwise.
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NealOnWheels
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Re: Quad Comparator Pins

Post by NealOnWheels »

You did not say which part you were using. A LM339 is a common comparator made by a number of manufacturers.

Here is the datasheet for National Semiconductors LM339:

http://cache.national.com/ds/LM/LM139.pdf

The top of page 18 has a good diagram of the DIP package.

Pin 1 markings may vary somewhat between manufacturers.
Kurt Wylde
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Re: Quad Comparator Pins

Post by Kurt Wylde »

Hello again,

Here is a picture of the chip in question:


Image

Any help determining pin 1 is appreciated.

Thank you.
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Stan Pope
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Re: Quad Comparator Pins

Post by Stan Pope »

Note the pic on page 18 of the referenced pdf (http://cache.national.com/ds/LM/LM139.pdf and compare to your pic. Almost invisible on the left end of your pic is a semicircular notch that identifies the "pin 1" end of the DIP. According to the page 18 pic, pin 1 is on the lower left of the pic.
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Kurt Wylde
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Re: Quad Comparator Pins

Post by Kurt Wylde »

Thank you Mr. Pope.
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Re: Quad Comparator Pins

Post by rangercmdr »

As NealonWheels and Stan said it in previous posts, pin #1 is in left lower corner as viewed from your picture, with pin number going up numerically in counter clockwise direction ending with pin #14 above pin #1. The notched end will be toward your left.
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