Anticipating timer switches
before you push the button - 04/03/03
EDN Design Idea This Design Idea offers a solution to the challenge of turning devices on or off in the
past. In Figure 1, IC2 is a 555-type timer (preferably CMOS) connected as a monostable one-shot multivibrator.
The pushbutton switch, S1, triggers IC2. You can replace S1 with a transistor or an optocoupler, for example.
You can connect VOUT to a relay or a transistor, if needed. You might need to adjust the values of R4 and R5,
depending on the output load and the characteristics of S1. The interval during which VOUT remains high is
T=1.1RC2. … [by Jean-Bernard Guiot, DCS AG, Allschwil, Switzerland]