Such was the case for one student, who had the canny idea to make a card that demonstrates his printed circuit board know-how. He used a 555 timer that outputs a clock to the LEDs on the biz card ...

Each of the candle lighting circuits, however, use a 555 timer both for its intended purpose ... blink an LED with the 555. [Sami] made a PCB of an Audi e-tron for a departing colleague.

and created his two alternating 500 Hz square waves with a 555 timer and a 74HC74D dual flip-flop. Unfortunately, he didn’t have the time to get a custom PCB made before Santa’s big night.

In this circuit, the renowned timer chip LM555 (IC1) is used as a PWM circuit. The whole circuit can be powered from a standard 12VDC supply, capable of sourcing ample current to the PCB drill motor.

Whenever I use the 555 timer, it seems that the output polarity is invariably incorrect, and the way the 555 functions, it normally cannot generate a duty cycle of less than 50% — 90% yes, 10% NO!

Just about anything can be made with a 555 Timer, and every circuit is fun to build, which I show in my book “Essential 555 IC: Design, Configure, and Create Clever Circuits.” In the book ...

Signetics released the venerable NE555 timer in 1971. It has been used in thousands of designs and has been the subject of at least that many articles (see “The 555: Best IC Ever Or Obsolete ...