555 vs 4001

hi guys,

am planning to use a cd4001 as a timer circuit instead of a 555 or 556. my question is, which one still better to use in terms of time accuracy and ruggedness.

pls. give your constructive comments and suggestions.

thanx

mozikluv said:

am planning to use a cd4001 as a timer circuit instead of a 555 or 556. my question is, which one still better to use in terms of time accuracy and ruggedness.

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I would have said the 555, it's the job it was designed for, plus it includes a reasonably powerful output stage. No free running RC oscillator/timer is going to have great accuracy, if you need that, a micro-controller would be much better - an 8 pin PIC is even the same size.

It all depends on your requirement.If you want long duration very accurate time intervals, CD4001 would be better choice.On the other hand the old friend 555 can sink or source currents up to about 200mA. It comprises 2 op-amps (used as comparators) together with an RS bistable element. In addition, an inverting output buffer is incorporated. A single transistor switch provides a means of discharging the external timing capacitors and operates from supply rail voltages of between 4.5V to 15V.

hi nigel & ravi,

thanks for your replies, your suggestion are well taken. for accuracy and low current need i would use the 4001 while for more current need and ruggedness i will just have to use the old reliable 555.