Measuring Stuff with a Multimeter...............................................................
A multimeter(see Figure 4-15) is a testing device that, um, tests multiple
things, including resistance, voltage, and current. Using certain multimeter
models, you can test to be sure that components — such as diodes, capaci-
tors, and transistors — function properly. You can also troubleshoot your cir-
cuit to see where current is failing and pinpoint the problem spot.You don’t have to break into your piggy bank to buy a multimeter. You can
find them for about $10; if you want fancy features, you can spend over $100.
Find a model whose price you like and then splurge on the next higher-priced
model. You will use a multimeter all the time. Trust us: It’s worth a few extra
bucks for a better model. See Chapter 3 for more information about multi-
meter features.How a multimeter works .....................................................................
A multimeter has a set of leads: a black one and a red one. You attach these
leads to the component or portion of the circuit that you’re testing, and a dig-
ital readout provides the results. You adjust a knob to set the test you wish to
perform such as resistance, voltage, or current as well as the range to test.
Note:Some multimeters have an auto-ranging feature that saves you the trou-
ble of setting the range.Figure 4-15:
The multi-
function
multimeter.76 Part I: Project Prep