tutorials:learn:multimeter:resistance.html
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tutorials:learn:multimeter:resistance.html [2010/10/18 20:37] daigo |
tutorials:learn:multimeter:resistance.html [2016/01/28 18:05] (current) |
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| |{{ http://www.ladyada.net/images/parts/resleft_t.gif?nolink&61x87 |}}|{{ http://www.ladyada.net/images/parts/rBrown_t.gif?nolink&10x87 |}}|{{ http://www.ladyada.net/images/parts/rBlack_t.gif?nolink&10x87 |}}|{{ http://www.ladyada.net/images/parts/rRed_t.gif?nolink&10x87 |}}|{{ http://www.ladyada.net/images/parts/spacer_t.gif?nolink&8x87 |}}|{{ http://www.ladyada.net/images/parts/rGold_t.gif?nolink&10x87 |}}|{{ http://www.ladyada.net/images/parts/resright_t.gif?nolink&66x87 |}}| \\ //This image shows a 1.0 kΩ 5% resistor (brown black red gold) // | |{{ http://www.ladyada.net/images/parts/resleft_t.gif?nolink&61x87 |}}|{{ http://www.ladyada.net/images/parts/rBrown_t.gif?nolink&10x87 |}}|{{ http://www.ladyada.net/images/parts/rBlack_t.gif?nolink&10x87 |}}|{{ http://www.ladyada.net/images/parts/rRed_t.gif?nolink&10x87 |}}|{{ http://www.ladyada.net/images/parts/spacer_t.gif?nolink&8x87 |}}|{{ http://www.ladyada.net/images/parts/rGold_t.gif?nolink&10x87 |}}|{{ http://www.ladyada.net/images/parts/resright_t.gif?nolink&66x87 |}}| \\ //This image shows a 1.0 kΩ 5% resistor (brown black red gold) // | ||
| </class> | </class> | ||
| + | This image shows a 1.0 kΩ 5% resistor (brown black red gold) | ||
| ==== What is resistance testing good for? ==== | ==== What is resistance testing good for? ==== | ||
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| Look for an ohm (Ω) symbol, if its a ranging meter there will be a bunch of subdivided modes. If its auto-ranging there will be only one. | Look for an ohm (Ω) symbol, if its a ranging meter there will be a bunch of subdivided modes. If its auto-ranging there will be only one. | ||
| - | {{ http://www.ladyada.net/images/metertutorial/wavetek_resmode.jpg?nolink&292x200 |}} \\ This meter has the Ω symbol and then 7 submodes, ranging from 200Ω to 2000MΩ (wow!) | + | {{ http://www.ladyada.net/images/metertutorial/wavetek_resmode.jpg?nolink&292x200 |}} |
| + | <class center> This meter has the Ω symbol and then 7 submodes, ranging from 200Ω to 2000MΩ (wow!) </class> | ||
| - | {{ http://www.ladyada.net/images/metertutorial/mas830_resmode.jpg?nolink&292x205 |}} \\ This meter has the Ω symbol and then 5 submodes, ranging from 200Ω to 2MΩ | + | {{ http://www.ladyada.net/images/metertutorial/mas830_resmode.jpg?nolink&292x205 |}} |
| + | <class center> This meter has the Ω symbol and then 5 submodes, ranging from 200Ω to 2MΩ </class> | ||
| - | {{ http://www.ladyada.net/images/metertutorial/extech_multimode.jpg?nolink&200x176 |}} \\ This meter has a multi-mode (you need to press a seperate MODE button to change between capacitor sense, diode test, resistor test and continuity!) It does not, however, have any numbered submodes, as it is auto-ranging | + | {{ http://www.ladyada.net/images/metertutorial/extech_multimode.jpg?nolink&200x176 |}} |
| + | <class center> This meter has a multi-mode (you need to press a seperate MODE button to change between capacitor sense, diode test, resistor test and continuity!) It does not, however, have any numbered submodes, as it is auto-ranging </class> | ||
| Line 75: | Line 79: | ||
| As long as it works, it doesn't matter which type you have. But auto-ranging meters are a little slower. \\ Compare these two videos as I measure a 1KΩ resistor with an autoranging meter: | As long as it works, it doesn't matter which type you have. But auto-ranging meters are a little slower. \\ Compare these two videos as I measure a 1KΩ resistor with an autoranging meter: | ||
| - | <script type="text/javascript" src="http://blip.tv/scripts/pokkariPlayer.js?ver=2007072801"></script><script type="text/javascript" src="http://blip.tv/syndication/write_player?skin=js&posts_id=338464&source=3&autoplay=false&file_type=flv&player_width=320&player_height=240"></script><img title="Click to play" alt="Video thumbnail. Click to play." src="http://blip.tv/file/get/Ladyada-autoranging1kohmTest476.flv.jpg" border="0" title="Click To Play" /> \\ Click To Play<script type="text/javascript"> play_blip_movie_338464();</script> | + | {{bliptv>338464}} |
| Which takes about 4 seconds to settle on a final value, and a 10KΩ resistor with a ranging meter: | Which takes about 4 seconds to settle on a final value, and a 10KΩ resistor with a ranging meter: | ||
| - | <script type="text/javascript" src="http://blip.tv/scripts/pokkariPlayer.js?ver=2007072801"></script><script type="text/javascript" src="http://blip.tv/syndication/write_player?skin=js&posts_id=338468&source=3&autoplay=false&file_type=flv&player_width=320&player_height=240"></script><img title="Click to play" alt="Video thumbnail. Click to play." src="http://blip.tv/file/get/Ladyada-ranged10kTest989.flv.jpg" border="0" title="Click To Play" /> \\ Click To Play<script type="text/javascript"> play_blip_movie_338468();</script> | ||
| + | {{bliptv>338468}} | ||
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| Ranges will almost always be something like 200Ω, 2KΩ, 20KΩ, 200KΩ, 2MΩ, etc. Why the 2s instead of 100, 1K, 10K etc.? Well, here's my guess. \\ Because the vast majority of resistors are 5%, the resistor values are 5% apart (or so). For example, the "standard" 5% values between 1K and 10K are: | Ranges will almost always be something like 200Ω, 2KΩ, 20KΩ, 200KΩ, 2MΩ, etc. Why the 2s instead of 100, 1K, 10K etc.? Well, here's my guess. \\ Because the vast majority of resistors are 5%, the resistor values are 5% apart (or so). For example, the "standard" 5% values between 1K and 10K are: | ||
| - | <p class="style1">1.0K, 1.1K, 1.2K, 1.3K, 1.5K, 1.6K, 1.8K, 2.0K, 2.2K, 2.4K, 2.7K, 3.0K, 3.3K, 3.6K, 3.9K, 4.3K, 4.7K, 5.1K, 5.6K, 6.2K, 6.8K, 7.5K, 8.2K, 9.1K | + | 1.0K, 1.1K, 1.2K, 1.3K, 1.5K, 1.6K, 1.8K, 2.0K, 2.2K, 2.4K, 2.7K, 3.0K, 3.3K, 3.6K, 3.9K, 4.3K, 4.7K, 5.1K, 5.6K, 6.2K, 6.8K, 7.5K, 8.2K, 9.1K |
| There are way more values between 1KΩ and 2KΩ than between 2KΩ and 3KΩ, etc. By picking 2KΩ as your max range, you get the best precision for the most probable values. | There are way more values between 1KΩ and 2KΩ than between 2KΩ and 3KΩ, etc. By picking 2KΩ as your max range, you get the best precision for the most probable values. | ||
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| [[http://www.ladyada.net/images/metertutorial/test10kpot.jpg|{{ http://www.ladyada.net/images/metertutorial/test10kpot_t.jpg?nolink&500x375 |}}]] | [[http://www.ladyada.net/images/metertutorial/test10kpot.jpg|{{ http://www.ladyada.net/images/metertutorial/test10kpot_t.jpg?nolink&500x375 |}}]] | ||
| - | <p align="left" >You can also use a multimeter to tell whether the potentiometer is a linear or logarithmic (audio) pot. When the pot is centered, if the resistance between the wiper and one end is half of the total value, its linear. (I used clips instead of probles to make it easier to take these photos)<p align="left" >This is a 10KΩ linear potentiometer<p align="center" >[[http://www.ladyada.net/images/metertutorial/linpotmin.jpg|{{ http://www.ladyada.net/images/metertutorial/linpotmin_t.jpg?nolink&500x375 |}}]] \\ The minimum resistance of the pot, 0Ω (a short) as expected <p align="center" >[[http://www.ladyada.net/images/metertutorial/linpotmid.jpg|{{ http://www.ladyada.net/images/metertutorial/linpotmid_t.jpg?nolink&500x375 |}}]] \\ Potentiometer centered, about 5KΩ<p align="center" >[[http://www.ladyada.net/images/metertutorial/linpotmax.jpg|{{ http://www.ladyada.net/images/metertutorial/linpotmax_t.jpg?nolink&500x375 |}}]] \\ Maximum value is 9.5KΩ (it should be around 10KΩ)<p align="left" > This video shows the resistance of a 10KΩ linear pot as it is adjusted. At the end it is set to approximately the midd, which is measured at 4.7KΩ, pretty close to the 'ideal' of 5KΩ. <script type="text/javascript" src="http://blip.tv/scripts/pokkariPlayer.js?ver=2007072801"></script><script type="text/javascript" src="http://blip.tv/syndication/write_player?skin=js&posts_id=338456&source=3&autoplay=false&file_type=flv&player_width=320&player_height=240"></script><img title="Click to play" alt="Video thumbnail. Click to play." src="http://blip.tv/file/get/Ladyada-10kPotTest467.flv.jpg" border="0" title="Click To Play" /> \\ Click To Play<script type="text/javascript"> play_blip_movie_338456();</script> | + | You can also use a multimeter to tell whether the potentiometer is a linear or logarithmic (audio) pot. When the pot is centered, if the resistance between the wiper and one end is half of the total value, its linear. (I used clips instead of probles to make it easier to take these photos) |
| + | This is a 10KΩ linear potentiometer | ||
| + | [[http://www.ladyada.net/images/metertutorial/linpotmin.jpg|{{ http://www.ladyada.net/images/metertutorial/linpotmin_t.jpg?nolink&500x375 |}}]] | ||
| + | <class center> The minimum resistance of the pot, 0Ω (a short) as expected</class> | ||
| + | [[http://www.ladyada.net/images/metertutorial/linpotmid.jpg|{{ http://www.ladyada.net/images/metertutorial/linpotmid_t.jpg?nolink&500x375 |}}]] | ||
| + | <class center> Potentiometer centered, about 5KΩ</class> | ||
| + | [[http://www.ladyada.net/images/metertutorial/linpotmax.jpg|{{ http://www.ladyada.net/images/metertutorial/linpotmax_t.jpg?nolink&500x375 |}}]] | ||
| + | <class center> Maximum value is 9.5KΩ (it should be around 10KΩ) </class> | ||
| - | Here are photos of a 50KΩ audio potentiometer[[http://www.ladyada.net/images/metertutorial/logpotmin.jpg|{{ http://www.ladyada.net/images/metertutorial/logpotmin_t.jpg?nolink&500x375 |}}]] \\ Minimum is 0Ω as expected | + | This video shows the resistance of a 10KΩ linear pot as it is adjusted. At the end it is set to approximately the midd, which is measured at 4.7KΩ, pretty close to the 'ideal' of 5KΩ. |
| - | [[http://www.ladyada.net/images/metertutorial/logpotmid.jpg|{{ http://www.ladyada.net/images/metertutorial/logpotmid_t.jpg?nolink&500x375 |}}]][[http://www.ladyada.net/images/metertutorial/logpotmid.jpg| \\ ]]Middle is 8KΩ | ||
| - | [[http://www.ladyada.net/images/metertutorial/logpotmax.jpg|{{ http://www.ladyada.net/images/metertutorial/logpotmax_t.jpg?nolink&500x375 |}}]] \\ Maximum is 54.2KΩ, close to the ideal 50KΩ | + | {{bliptv>338456}} |
| - | \\ If, when centered, the resistance is more like 85% or 15% of the total resistance, then its a log pot. This is a 50KΩ analog potentiometer. When centered, the resistance is about 8KΩ. | ||
| + | Here are photos of a 50KΩ audio potentiometer[[http://www.ladyada.net/images/metertutorial/logpotmin.jpg|{{ http://www.ladyada.net/images/metertutorial/logpotmin_t.jpg?nolink&500x375 |}}]] | ||
| + | <class center> Minimum is 0Ω as expected</class> | ||
| + | [[http://www.ladyada.net/images/metertutorial/logpotmid.jpg|{{ http://www.ladyada.net/images/metertutorial/logpotmid_t.jpg?nolink&500x375 |}}]] | ||
| + | <class center>Middle is 8KΩ</class> | ||
| - | <script type="text/javascript" src="http://blip.tv/scripts/pokkariPlayer.js?ver=2007072801"></script><script type="text/javascript" src="http://blip.tv/syndication/write_player?skin=js&posts_id=338482&source=3&autoplay=false&file_type=flv&player_width=320&player_height=240"></script><img title="Click to play" alt="Video thumbnail. Click to play." src="http://blip.tv/file/get/Ladyada-50kLogPotTest480.flv.jpg" border="0" title="Click To Play" /> \\ Click To Play<script type="text/javascript"> play_blip_movie_338482();</script> | + | [[http://www.ladyada.net/images/metertutorial/logpotmax.jpg|{{ http://www.ladyada.net/images/metertutorial/logpotmax_t.jpg?nolink&500x375 |}}]] |
| + | <class center>Maximum is 54.2KΩ, close to the ideal 50KΩ</class> | ||
| + | |||
| + | If, when centered, the resistance is more like 85% or 15% of the total resistance, then its a log pot. This is a 50KΩ analog potentiometer. When centered, the resistance is about 8KΩ. | ||
| + | |||
| + | |||
| + | {{bliptv>338482}} | ||
| + | |||
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| After setting the range, I experiment with shading it on video | After setting the range, I experiment with shading it on video | ||
| - | <script type="text/javascript" src="http://blip.tv/scripts/pokkariPlayer.js?ver=2007072801"></script><script type="text/javascript" src="http://blip.tv/syndication/write_player?skin=js&posts_id=338479&source=3&autoplay=false&file_type=flv&player_width=320&player_height=240"></script><img title="Click to play" alt="Video thumbnail. Click to play." src="http://blip.tv/file/get/Ladyada-LDRTest844.flv.jpg" border="0" title="Click To Play" /> \\ Click To Play<script type="text/javascript"> play_blip_movie_338479();</script> | + | {{bliptv>338479}} |
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