Archive for September 2015

Direct Measurement of the Speed of Light using a Cheap Laser Diode – I

Speed of light c in air can be measured either directly or indirectly. There are many ways to infer c with indirect measurements. For instance, we can measure the propagation delay of a signal through a coaxial cable (or an optical fiber) using the TDR analysis. With the length of the coax or optical fiber known, the speed of light can be calculated using the known velocity factor (or the refractive index of the fiber) and the measured propagation delay. Another example of indirect measurement is to measure the wavelength of a known frequency standing wave (e.g. a microwave signal) and derive the phase velocity of the electromagnetic wave in air. Continue reading ‘Direct Measurement of the Speed of Light using a Cheap Laser Diode – I’ »

Testing Unknown Transformers with Function Generator

Last week, I posted a YouTube video explaining how to use a function generator to test an unknown transformer. I have received quite a few questions since so I thought I would explain this topic a bit more in detail here. Continue reading ‘Testing Unknown Transformers with Function Generator’ »

Keithley 706 Scanner Teardown

I bought this Keithley 706 scanner on eBay a while ago. This scanner can take up to ten different scanner cards and is typically used in an automated testing environment. In this blog post, I will show some of the teardown pictures and a couple of the scanner cards (7064, 7152) included in this unit. A quick teardown video is included towards the end. Continue reading ‘Keithley 706 Scanner Teardown’ »