Posts tagged ‘Keithley 614’

Diode Equation and Forward Current Measurement

We are all familiar with the I/V characteristics of a diode. The main characteristics of a typical diode is that when forward biased, it starts to conduct as the voltage applied approaches the threshold voltage of the diode and the current increases exponentially as the forward voltage increases. This behavior can be modeled by the Shockley diode equation. A question frequently asked is that what happens when the applied forward voltage is very small, say just a few millivolts? Continue reading ‘Diode Equation and Forward Current Measurement’ »

When to Use An Electrometer?

Electrometer is a piece of highly specialized electronic test equipment. Most of us would naturally associate it with low-level measurements (e.g. low current pA, fA and high resistance GΩ measurements) only, but the situations under which you might need to use an electrometer are actually far more common then you might have thought. In this post I will discuss a couple of situations where using an electrometer is crucial. And at the end of the post I included a video for some demonstrations. Continue reading ‘When to Use An Electrometer?’ »

Keithley 614 Electrometer Teardown

In this blog post, we will take a look inside a 1980 vintage Keithley 614 Electrometer. While it was designed and built more than three decades ago, its performance is still pretty impressive (10 fA current resolution) even compared with today’s modern standards. Its performance was only rivaled by Keithley 617 in its days. Continue reading ‘Keithley 614 Electrometer Teardown’ »