Using the meter

You can use the meter to measure voltage (pressure), current (flow) or resistance. It does a few other things but lets not worry about that just yet. Most of the experiments you do will not need the meter, you can use the bulbs, LED or buzzer to see if anything is working. However, if you want to make a potato battery (or similar), then the meter will tell you if things are working as the power provided by a potato is usually not enough to light a bulb.

The most common things you will use the meter for are measuring voltage and checking continuity (seeing if there is a circuit connection).

Checking Continuity

Plug the meter wires into the meter (see meter instructions) and turn the switch round until it points to the buzzer/diode symbol. If you touch the two probes together, the meter should beep. So whenever there is a circuit between the two probes, you get a beep. For continuity to work, you need to disconnect the battery. Select the microswitch module. You will notice it has three connections. The middle one is common and one of the others is connected to common when the switch is open, the other one when the switch is closed. Connect the meter (in continuity mode) between the middle terminal and one of the others. It should beep on one set of connections and not on the other. Now press the switch, you will see their roles are reversed. You can do the same with the toggle switch. The same is true for the relay contacts. I've not marked any of the contacts as I thought you would like to work out which is which.

Checking Voltage

The voltage (pressure) across a circuit can be measured by setting the meter switch to one of the V modes (with a _, not the ~). This measure dc voltage (what a battery outputs). If you set the meter to (~), it will measure ac voltage (what powers our houses) then the meter will display misleading readings when measuring battery circuits. If you set the meter to 20 Volts dc and measure across the battery module, you should see about 6.0 volts if you are using standard batteries. This makes sense as each battery is 1.5V, so 4 of them in series gives 4x1.5 = 6 Volts. If you are using rechargeable batteries, you might see about 4.8V instead. This is because rechargeable batteries are about 1.2V each, so 4x1.2 = 4.8V