How to Use a Multimeter and Where to Buy
If you do not have a multimeter, they can be found at low cost online and also at most hardware stores locally, from around $15 on the lowest end.
Important!
Make sure your meter probes are plugged into the voltage input. Typically labeled “V”.
Do NOT use the current measurement port.
Make sure while the probes are touching the item that you’re measuring, that you do not allow the probes to touch together as this will cause a short circuit.
How to use it
Set your meter to the DC voltage mode (solid line on top with dashed lines underneath), if it has multiple ranges, use one that is 60V or higher. Typically this will be the 200V option, but some meters are auto-ranging and will simply have a voltage mode.
Next touch the probes to the contact points you want to measure, polarity does not matter for a digital multimeter so you can swap the red and black probes around without any issues.
Here are a few examples: