Oscilloscopes Print
Written by Richard Feltham   

Oscilloscopes: seeing is believing

An oscilloscope displays a changing electrical voltage as a visual pattern. We are all familiar with these devices, thanks to the plethora of medical television programs that show the poor patient’s heart monitor flatlining in ER as the struggling staff attempt to resuscitate him. This is simply an oscilloscope doing what it does best—measuring low voltages with great precision in real time.

If you invoke Ohm’s Law you can also obtain measurements of resistance, inductance and capacitance. The digital age has made these available at modest cost, around a few hundred dollars for a basic model. If you are using electronics in your shed in anything more than a trivial way then an oscilloscope is a valuable and incredibly versatile tool.

It moves into the essential bracket if you are dealing with complex waveforms and pulse timing from digital circuits. Being able to see what your Arduino programming is actually doing is a huge help in debugging.

Spurred on by the recent Shed article on quadcopters (“A drone of your own,” Aug/Sep 2014), I spent several enjoyable weeks building my own version. With everything tested and working correctly on the ground, I launched into the maiden flight, only to have it go out of control after 20 or so seconds and crash in the most spectacular, and terminal, fashion. The various flight controls had just seemed to stop working.

I recovered the radio parts and tested them with the oscilloscope. The aileron (yellow) and elevator (blue) pulses follow each other in time at a constant rate of 48.1630 Hz. With the stick in neutral the pulse widths are about the same, around 1.20 milliseconds (mS) in duration.

Read more in the latest issue of The Shed