Posts tagged ‘Keithley 197’

ESR Measurement Using Multimeter and Function Generator

Capacitor ESR (Equivalent Series Resistance) measurement is very useful in diagnosing issues with power supplies. In linear power supplies, a high ESR filter capacitor may cause excessive ripple current on the voltage rails and can cause the capacitor to overheat due to its increased resistance. In low dropout linear supplies, the ESR of the output capacitors affect the loop stability and excessive ESR in these output capacitors can make the power supply unstable, which in turn can lead to out-of-tolerance voltage being applied to the load and could cause future damages. In switching mode power supplies, the ESR of capacitors are even more critical. In this blog post I will discuss how to measure the ESR of a capacitor using a function generator and a multimeter. A short video on this topic is also included towards the end. Continue reading ‘ESR Measurement Using Multimeter and Function Generator’ »

Keithley 197 Battery Option Build

I have been quite happy with my fixed-up Keithley 197 5 ½ digit bench meter purchased from eBay (you can find the teardown pictures here) earlier this year. Keithley 197 has a battery pack option (Model 1978), and this option allows it to run on battery power for 5 hours without having to plug into the mains. While it is far from being a truly portable meter, its performance easily surpasses most hand-held multimeters. So I decided to build the battery option myself and hopefully I would be able to use the meter more often in places where power outlets are not available. Continue reading ‘Keithley 197 Battery Option Build’ »

Keithley 197 Teardown and Repair

A few days ago, I bought a Keithley 197 sold as “unknown working condition” on the cheap. The seller said that some of the keys on the meter were unresponsive. I figured that I’d try fixing it if I could. After all, these 5 ½ meters still fetch well over $100 on eBay and for a fraction of that price, I was willing to give it a shot. Continue reading ‘Keithley 197 Teardown and Repair’ »

Backup and Flash Firmware using Arduino

A while ago, I did a tear-down of a Keithley 196 bench multimeter. Towards the end of that post I showed a picture of my breadboard setup for backing up the firmware EPROM (27128) in case I needed to re-flash the firmware in the future. Since then, quite a few people had asked me to provide more details on how to do this using an Arduino. So I thought I would explain a little more here. Continue reading ‘Backup and Flash Firmware using Arduino’ »