Over the years with different companies I’ve worked for, I always had access to high-end audio THD (Total Harmonic Distortion) analyzers. I found these very useful for design work, debugging, and repair of audio equipment. My present company has no need for them and consequently they aren’t included in their armory of test equipment. Oftentimes, I have need for one but could never afford to own one — not even a used one. I thought this would be a worthwhile project, so this article describes how to construct one.
Sometimes I wonder which of my portable digital voltmeters I can trust — the B&K, Fluke, or Amprobe. Usually, they’re pretty close but it bugs me not knowing whether they are right on the nose. Fortunately, these days, there are a number of very accurate voltage reference circuits that you can build or purchase for a few dollars.
If you’re like me, you likely have a drawer or shoe box stuffed with assorted USB cables that are used to either charge or program a USB device. The problem often is that some cables may only be useful for charging, and which only have the +Vcc and ground wires intact with one or both data wires either broken or not connected in the first place. Here’s a simple test jig to help you tell what’s what.
During a recent vacation, I challenged myself to come up with a design for a continuity tester that suits my particular testing requirements. Most of the time, I go straight for a microcontroller, but this time I decided to use only non-programmable components. I also decided to use only through hole components, to make soldering easier.
This DIY piece of test equipment combines a variable DC voltage reference, a programmable function wave generator, and a fully functional frequency counter. Plus, it costs under $200. It started out as a microcontroller controlled variable voltage reference using just a PIC, a fixed voltage reference, and a digital-to-analog converter. However, it expanded to include a programmable function generator that can produce a sine wave, triangle wave, square wave, etc. I then went further to include a frequency counter to measure the frequency of the function generator output.
In decades past, capacitor and resistor substitution boxes were very popular pieces of test equipment. These days, it seems folks have forgotten their value and ease of use. Here’s a discussion on how they work and the different options and styles available, so you can start using them for yourself.
Internal resistance within capacitors — known as Equivalent Series Resistance — can increase over time, causing power loss and/or heating. With this device, you can test your stash of capacitors so you can weed out any bad ones before you install them in your projects.
For most of us, measuring DC current means putting an ammeter or low resistance current shunt in the line. But now, you can build an adapter that can be used with your voltmeter and will measure 100 amps DC.
I can hardly imagine an electronics enthusiast without some sort of test bench. This can be as simple as a folding table and a couple of hand tools, along with a cheap DMM (Digital MultiMeter). Or, it can be as elaborate as a spare room just loaded with TE and a full complement of tools and accessories to go with it.
Frequency counters have been around for years as a standard piece of test equipment in both commercial and hobby labs. If you need one for your workshop, take a gander at the one discussed here.
