In the classic configuration and most variants of the astable 555 multivibrator circuit, the timing characteristics are based on the charging and discharging of a capacitor. However, it can be argued ...

The circuit was designed sensitive enough to trigger and activate the alarm upon sensing wetness, moisture or dampness on its probes. 555 Timer – an 8-pin electronic device used in several mixtures of ...

There is many a comment on these here pages along the lines of “Why did you use a microcontroller, when you could just have easily used a 555 timer!” And, yes, we sometimes agree with the sentiment, ...