Get By Tony Van Roon By Tony Van Roon The 555 Timer ... - Engineering

The 555 timer IC is an integrated circuit (chip) used in a variety of timer, delay, pulse generation, and oscillator applications. Derivatives provide two (556) or four (558) timing circuits in one package. The design was first marketed in 1972 by Signetics and used bipolar junction transistors.

Monostable multivibrator, in which one of the states is stable, but the other state is unstable (transient). A trigger pulse causes the circuit to enter the unstable state. After entering the unstable state, the circuit will return to the stable state after a set time.

Monostable multivibrator The time for which output remains high is determined by the external RC network connected to the timer. At the end of the timing interval, the output automatically reverts back to its logic-low stable state. The output stays low until trigger pulse is again applied. Then the cycle repeats.

Hans R. Camenzind (Swiss Standard German: [ˈkaːməntsɪnd]; 1 January 1934 – 8 August 2012) was an electronics engineer known for designing the 555 timer IC in 1971 under contract to Signetics. He was the inventor on 20 US patents.

In the monostable mode of the 555 timer, also known as the "one-shot mode", when we apply a logic LOW to the trigger pin of the timer by closing the switch, the output becomes logic HIGH and holds there for a specific time duration (T), which is decided by the values of the externally connected resistor and capacitor.

555 Timer IC Internal Circuit Depending on the manufacturer, the standard 555 timer package includes 25 transistors, 2 diodes, and 15 resistors on a silicon chip installed in an 8-pin mini dual-in-line package (DIP-8). Variants consist of combining multiple chips on one board.