7 Non-linear applications

  • interactive animation of a trigger circuit: iPES Zurich

The 555 timer is sometimes referred to as „the time machine“. It has historically been of great importance in the generation and detection of temporal signal sequences.
Before discussing the device itself, the various modes should be briefly considered:

Mode^other name^explanation^application^examples^

astableoscillator, multivibratoroutput signal changes value periodicallycreation of a periodic, rectangular signal, with adjustable pulse width and frequencymotor control, dimming of LEDs, generation of tones
monostable„flip-flop“, monoflopOutput signal is triggered by a trigger and goes back to 0V after a defined timeExtending pulses that are too short, setting a fixed pulse lengthConditioning sensor signals of a proximity sensor
bistableflipflopset/reset when thresholds are exceeded/fallen shortbounce-free switch, circuits with hysteresistwo-point controller, e.g. for heating elements

It can be seen that there are a wide variety of applications for this component. The question can be asked what differentiates the application of this component from a microcontroller:

PropertyMicrocontrollerTimer 555
Cost (single unit, 2018)from 3ct (chin. µC, PADAUK PMS150C)from 29ct (western µCATtiny)
cost (>10'000, 2018)from approx. 2..3ct (chin. µC)from 20ct (westl. µC) from 2..3ct
other componentsinterference suppressioninterference suppressiontransistors, resistors and other capacitors depending on the application
Complexityin softwarehardly available
FlexibilityUpdates possibleif potentiometers were used, limited
advantages for small quantitieseasily changeable by programming, \no component scatteringeasily changeable by reassembling on the board, \no software bugs, \no tools necessary

For a long time, the Timer 555 was the most cost-effective solution for the tasks mentioned above. Currently (2018), Timer 555 and microcontroller prices are about the same in large quantities. Nevertheless, due to its simplicity, the Timer 555 is still found in various consumer electronic products.