Since its introduction nearly 40 years ago, the 555 timer IC and its companion 556 dual timer have inspired hobbyists, technicians, inventors, engineers, and many others who love to experiment with electronic circuits. An Internet search on "555 timer" yields millions of hits. Using "555 timer projects" as the search phrase yields more than 800,000 hits.
Many projects are games and hobbyist-level circuits such as traffic lights, electronic dice, flashing LEDs, sirens, just to scratch the surface. Other circuit designs have more pragmatic applications such as switch de-bouncing, two-button safe start, timers, PWM, and counter circuits. Regardless of whether a project is for work or fun, 555 timer circuits are bistable, monostable, astable, or combinations of these.
In order to test 555 timer circuit projects when Signetics first introduced the device, you would have needed a voltmeter and an oscilloscope at the very least. The digital multimeter (DMM) didn't appear on the scene until 1977 when Fluke introduced the 8020A—the first successful handheld DMM. Now, the DMM and oscilloscope are combined in one portable instrument, Fluke's ScopeMeter®.
Fluke has a new ScopeMeter® line—the Fluke 190 Series II test tools. In addition to longer battery life and a USB port, the new handheld oscilloscopes have four channels. Multiple channels are handy for simultaneously viewing multiple waveforms and triggers. When testing electronic circuit projects, maintaining electronic equipment, or troubleshooting industrial facilities you can use these portable oscilloscopes to view signals for proper waveforms or glitches, calculate period and frequency, identify malfunctioning components, verify timing of digital circuits, troubleshoot noise-related problems, and many other tasks.