Timer circuits ( 10 ) :

Timer circuits are circuit which are trigged by input pulses.When they are triggered, they will wait for a predeterminedtime to change the output state. The most commonly used timer circuitsare monostable multivibrators and time delay circuits.A time delay circuit works so that when the input comes active,the output gets activated after a predetermined time.A monostable multivibrator works so that a trigger pulse actives it,the output turns active. After a predetermined time the monostablecircuit deactivates itself and the output.Many astable timer circuits are based on 555 timer IC.Designing astable circuits using the industry-standard 555 timer is a straightforward process when duty cycles are 50% or greater. This IC can also be used for many other applications.

• A Technique For Forming Long Time-Constants   
• Design low-duty-cycle timer circuits - Designing astable circuits using the industry-standard 555 timer is a straightforward process when duty cycles are 50% or greater. However, you must overcome the many pitfalls of low-duty-cycle circuits to arrive at a desired result. This Design Idea uses the TLC555 CMOS timer.   
• HEF4538B Dual precision monostable Multivibrator IC Datasheet - The HEF4538B is a dual retriggerable-resettable monostable multivibrator. Each multivibrator has an active LOW trigger/retrigger input (I0), an active HIGH trigger/retrigger input (I1), an overriding active LOW direct reset input (CD), an output (O) and its complement (O), and two pins (CTC,(1) RCTC) for connecting the external timing components Ct and Rt. The duration and accuracy of the output pulse are determined by the external timing components Ct and Rt.   
• LM555 timer chip datasheet - very popular timer IC for all kinds of applications, check also   
• Logic IC yields simple, wide-range timer - you can use a 4060B binary counter/oscillator to make a simple, accurate, long-delay timer for times between milliseconds and hours   
• Long Delay Timer - A max. delay of 20 hours is achieved by this relatively simple circuit.   
• One-shot circuit is programmable - digitally program the on-time of a one-shot multivibrator circuit based on NE555 timer and AD7524 DAC   
• Simple timer exploits op-amp bias current - simple, low-cost analog timer exploits the parasitic input-bias current of op-amp to achieve long time delays even though it uses only low-value, inexpensive ceramic chip capacitors   
• Timer provides power-off function - an interval from seconds to several minutes for automatic power-off switching in idle battery-powered systems   
• �C-based one-shot has wide range - �C-based, digitally programmable, monostable multivibrator based on PIC16C54   

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