If you are building the electronic guts of many robots, you will often need to test circuit function and component values.
Having, and knowing how to use a multimeter is an invaluable skill. The first peice of advice I will offer any new robot builders is to buy a Digital one. Analog ones are awkward to read, not very precise, and to be frank a bit obsolete.
Entry level multimeters should cost no more than around £15 (less if you really look around at computer markets). They should also come with one set of probes - though eventually you might think about getting others. Also consider how many digits it will display - again- for entry level, four should be sufficient. If a manufacturer specifies 3.5 - they mean the first digit can only display a 1.
Most multimeters have enough functionality to read resistance, current and voltage.
Since resistors are one of the most common components you are working with - you will regularly use this one. All the settings marked with the Ohm Symbol & are resistor markings. There are a set of different resistor value ranges, so you try and go with the nearest one - or start low. If you test the resistance, and see NO or 1, try shifting up to a higher setting. Most go from 1Ω (on the 2Ω setting) up to 2MΩ - this is a very high resistance, and although I have seen them, it is very rare you will use a resistor over this rating. For each setting- you are able to measure resistances less than, or equal to it. Some meters are “Auto-Ranging” - so you do not have to select a setting. Even if you are familiar with the resistor colour bands, I often check the resistance anyway, because some resistors (especially if salvaged) may be damaged and offer a much higher, or lower one than printed. If you are totally trusting of the colour bands, and do not check - you may find you have to desolder a dud.
The next tool you will regularly use is continuity checking. It is often very worthwhile knowing if a circuit, or cable is clear-flowing and not broken. On some multimeters- you will have a specific setting, and an LED or Tone which sounds when the check is successful. On others- many of the entry-level ones, you can use the diode test functionality.
|Digital Multimeter With Backlight||Draper||You might not use the backlight much but there will definately be situations where you will have wondered how you did without it. I prefer this rotary kind of MultiMeter. Ensure you buy a digital one like this as the analogue ones really do not live up to what a roboticist will require. It is cheaper from Amazon than many local tool shops - and has all of the beginner functions for measuring resistance, current and voltage. It also has Diode and Transistor testing.|
|Getting the Most from Your Multimeter...||R.A. Penfold||If you are serious about using a multimeter- or interested in using one for more purposes - this is a great little book - at less than a fiver, why not. OrionRobots has a collection of the R.A. Penfold books - which while small, come highly recommended.|
|Junkbots, Bugbots and Bots on Wheels: Building Simple Robots with BEAM Technology||Dave Hrynkiw, Mark W. Tilden||I recommend this book again - as it has a neat little section on using a multimeter and other electronic stuff. Since you can build robots with it as well - you should probably have this in your library.|