Even the lowest grade frequency counters are often the most accurate instruments on the bench. Here, we'll describe their general principles of operation, construction and retrofitting into existing equipment, all the way to a full blown universal counter.
No test bench is complete until it has an RF signal source of some type. Here is a sweet general purpose RF signal generator that won’t take up much space and can be built on the cheap.
Sweep generators have a lot of uses in the design, prototyping, and troubleshooting of amplifiers, filters, and radio circuitry. They can greatly speed up these tasks by presenting many parameters at one time. Your bench could be sporting a unit like this for around $100 in parts... plus your labor, of course.
As an experimenter, I use wall warts all the time to power circuit boards, microcontroller boards, and even finished projects. However, during the checkout phase of a new circuit, wall warts present a problem. How do you measure their output when they’re plugged into a board or project box?
Do you get erratic results with your oscilloscope? As you start probing higher and higher frequencies, do the results get increasingly odder? Let's address the reasons for that strange behavior and construct an inexpensive Active Probe.
Ground faults are a curse to fire alarm systems. Even a small amount of current leaking to ground somewhere in the building can cause an unscheduled fire drill. Worse yet, a second ground fault somewhere else in the building can short out the whole system. An easy modification allows a low tech analog ohmmeter to detect insulation faults that a high tech digital ohmmeter fails to find.
Since deluxe versions of variacs can run $500 and up, many hobbyists can not afford or justify buying a new one. But rather than do without, this article presents a high grade, DIY, alternative to a commercial unit, that should fit any budget.
After years of fumbling with capacitors and signal generators, it’s extremely gratifying to be able to touch any old inductor to the contact pads and have the meter tell me its value. I hope you’ll find this device as useful as I do.
Every bench needs a power supply to fully complement the rest of its test equipment. This dual channel, regulated, supply may be just what you need for design and repair of low and mid-power circuitry.
Okay, you’ve wired up the latest whiz-bang sensor to your processor-controlled project. The sensor has been connected to the 12-bit A/D and now the moment of truth. You apply power and look at the data ... Hmmmm, the numbers don’t look quite right.
