Oscilloscope

An oscilloscope is tremendously valuable for finding minute problems that can't be found any other way. It measures electronic signals and displays them on a visual screen as a "wave" form. Various wave patterns mean different things, and by reviewing the wave pattern you can discern specific issues when things aren't working.

You can determining the frequency and amplitude ("height") of a signal, measured in volts or millivolts. These are critical elements to the successful operation of many electronic circuits and certainly those inside light controllers. If a signal isn't there, is too strong or isn't strong enough, or isn't operating at the right frequency it can easily cause a circuit to fail. An oscilloscope can help you uncover electrical noise in your circuit. When there's a lot of noise present, the noise sometimes covers the desired signal so it can't be understood by the electronics.

Oscilloscopes are measured by their speed, and the faster the oscilloscope, the more exact it can analyze signals. But a 10mhz scope would obviously have difficulty measuring a crystal that's running at 18.432mhz because it's not fast enough. 50mhz and even 100mhz oscilloscopes aren't horribly expensive but still, they're a luxury diagnostic tool to own even if they're in the $300-$500 price range. Much faster scopes are certainly available but the price skyrockets rather quickly. You can sometimes find good buys on used oscilloscopes, too.

An example of how an oscilloscope can help in this hobby is by detecting the "zero cross signal" which is so important to being able to dim lights effectively using A/C current. The ZC is happens 120 times per second with normal 60hz electricity, and if the controller can't recognize it, dimming A/C lights gets very inconsistent. Here's what the ZC signal looks like on a 'scope: