Sometimes the best inspiration is limitation. The 555 timer does “one thing” — compares a voltage to a couple thresholds and outputs a signal accordingly. It’s two comparators, a voltage ladder, and a ...

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!

Click here to view a PDF of all the Design Ideas from this issue. Using a CMOS 555 timer and a single NPN transistor, you can drive as many as seven LEDs using a minimal amount of voltage and power ...