The NE555D is a precision timing circuits capable of producing accurate time delays or oscillation. In the time-delay or monostable mode of operation, the timed interval is controlled by a single external resistor and capacitor network. In the astable mode of operation, the frequency and duty cycle can be controlled independently with two external resistors and a single external capacitor. The threshold and trigger levels normally are two-thirds and one-third, respectively, of VCC. These levels can be altered by use of the control voltage terminal. When the trigger input falls below the trigger level, the flip-flop is set, and the output goes high. If the trigger input is above the trigger level and the threshold input is above the threshold level, the flip-flop is reset and the output is low.

Note: Image may vary from actual product in terms of Manufacturer/Brand name according to the availability. 

Features:

1. Timing from microseconds to hours
2. A stable or monostable operation
3. Adjustable duty cycle
4. TTL compatible output can sink or source up to 200mA
5. Applications: Clock & Timing, Consumer Electronics, Aerospace, Defence, Military, Embedded Design & Development