==== Introduction  ====
The most important debugging tool in any E.E.'s toolbox is a trusty multimeter. A multimeter can measure continuity, resistance, voltage and sometimes even current, capacitance, temperature, etc. It's a swiss army knife for geeks! 
==== What you will learn!  ====
You should go through all of these sections in order, as they build on each other.
  *[[http://www.ladyada.net/learn/multimeter/continuity.html|Continuity measurements]]  \\ How to tell if two points are electrically connected 
  *[[http://www.ladyada.net/learn/multimeter/resistance.html|Resistance measurements]]  \\ How to measure resistance - resistors, potentiometers and sensors 
  *[[http://www.ladyada.net/learn/multimeter/voltage.html|Voltage measurements]]  \\ How to measure voltage - battery testing, wall-wart adaptor testing, and the terror of mixed AC/DC measurements.  
==== What to look for?  ====


Everyone always asks **What multimeter should I get?** 



Well, since they're rather commodified (there are dozens of manufacturers) it is hard to make everyone use the same model, even though it would make things easier.



These are the necessities: 


  *Continuity testing with piezo buzzer
  *Resistance test down to 10 ohm (or lower) and up to 1 Megaohm (or higher) 
  *DC voltage test down to 100mV (or lower) and up to 50V
  *AC voltage test down to 1V and up to 400V (or 200V in the US/Canada/Japan)
  *Diode testing

Here are nice things to have in your meter


  *Auto-off - to keep from draining the batteries
  *AC and DC current test, from 10mA to maybe 200mA and then also a 10A one as well 
  *Stand - a thing that flips out and keeps it upright on your table
  *Auto-ranging - note: some people don't like auto-ranging because its slower and not as precise 
  *Hold - keep the maximum value on the screen so you can probe without looking at the meter.
  *Common battery - such as 9V or AA's, pocket meters use hard-to-replace coin cells 

These are things that I rarely (if ever) use, in decending order 


  *Frequency counter - before I had a scope this was surprisingly useful!
  * Capacitance testing - usually to check random SMT caps
  *Inductance testing - how often do you really use an inductor?
  *Duty cycle - never used this 
  *Transistor beta meter - people don't really work with transistors anymore 
  *Temperature probe - I use the "Pease temperature test": a finger  
==== Where to get one?  ====


I have a selection of [[http://www.ladyada.net/learn/../library/equipt/kits.html|suggested meters on this page]], I strongly suggest the "[[http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=220759|better]]" (At $15 its a great value) or "[[http://www.jameco.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10001&catalogId=10001&productId=645626|best]]" ($50, autoranging, has a temp probe, all sorts of other junk) ones as the "good" one is really kinda bad. If you already have a multimeter then just use that one. I'll only be covering digital multimeters here so if you have an analog one, it may be a little different and you'll have to experiment to figure out what's up 



A good multimeter will cost about $25. I suggest getting a ranging one , with current testing, and a wide range as well as easy-to-replace battery. You don't need to spend [[http://us.fluke.com/usen/products/Fluke+73+77.htm?catalog_name=FlukeUnitedStates|$200 on a Fluke 73]]! A $50 meter will be excellent. Auto-ranging meters may keep you from tripping up on ranges at first, but they're slower and often flakier. 



I have had a [[http://www.inotek.com/Catalog/wavetek1et.html|Wavetek Meterman 27XT]] for half a dozen years and its been really good to me, but it was also about $80.


==== More links  ====


Here are many other links for learning how to use a multimeter


  *[[http://tangentsoft.net/elec/movies/tt06.html|TangentSoft's half-hour video tutorial]]
  *[[http://www.makezine.com/blog/archive/2007/01/multimeter_tuto.html|Make Magazine's Bre & Joey Grand on how to use a multimeter ]]
  *[[http://www.robotplatform.com/tools/multimeter/multimeter.html|Robot Platform tutorial on using digital multimeter]]