Changes between Version 11 and Version 12 of ElectricalIntroduction

Timestamp:

Aug 21, 2017, 11:12:03 AM (8 years ago)

Author:

David Albert

Comment:

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ElectricalIntroduction

@@ -27 +27 @@
 
 == Multimeter ==
-You can use a meter called a voltmeter or a [multimeter to measure the amount of voltage "pressure" a battery exerts.  Multimeters are inexpensive ($5-25) and incredibly useful; every house should have at least one.  To learn how to use a multimeter, see [https://learn.sparkfun.com/tutorials/how-to-use-a-multimeter this tutorial]
+You can use a meter called a voltmeter or a [multimeter to measure the amount of voltage "pressure" a battery exerts.  Multimeters are inexpensive ($[https://www.harborfreight.com/7-function-multimeter-98025.html 5] - [https://www.amazon.com/UNI-T-Digital-Multimeter-Frequency-Resistance/dp/B00AW6SHNO 25]) and incredibly useful; every house should have at least one and every robotics student and mentor should be comfortable using a multimeter.  More expensive meters can usually measure more things and require fewer manual steps.  For example, some multimeters require that you select a range of voltages to measure such as 2V, 20V, 200V, etc. whereas other multimeters will automatically select the proper measurement range (called ''auto-ranging'' meters).  To learn how to use a multimeter, see [https://learn.sparkfun.com/tutorials/how-to-use-a-multimeter this tutorial].  We'll use multimeters in the next few exercises.
+
+Multimeters include two wires called probes or leads which are used to connect the meter to whatever it is measuring.  The leads can usually be unplugged from the meter for replacement, easier storage, and sometimes for making special measurements.
 
 [[Image(UT136B.jpg,left,20%,nolink)]] [[Image(Cen-Tech_Multimeter.jpg,20%,nolink)]] [[Image(measure_AA.jpg,20%,nolink)]] [[Image(measure_SLA.jpg,20%,nolink)]]
 
 * Exercise: Use a multimeter to measure the voltage of a battery:  
-    * Turn the multimeter on and move the range selector knob to DC Volts (often shown as DCV or a dashed line over a solid line)
-    * Plug the black wire into the hole labeled COM
-    * Plug the red wire into the hole labeled V/mA/...
+    * Turn the multimeter on and move the range selector knob to DC Volts (often shown as DCV or a dashed line over a solid line).  If you are not using an auto-ranging meter, choose the voltage range that includes the battery you will measure (e.g. the 20V range if you are going to measure a 12V battery)
+    * Plug the black probe wire into the hole labeled COM
+    * Plug the red probe wire into the hole labeled V/mA/...
     * Touch the other end of the black wire to the negative (-) terminal of the battery
     * Touch the other end of the red wire to the positive (+) terminal of the battery