Design of process control timer

Maybe a 4017 Johnson counter + clock cct?? Maybe a MLS (maximum length sequence) generator cct + clk? Maybe a binary counter IC + clk?? Maybe just a bunch of clk's? Those goes on and off with a particular sequence :) I think you're going to get asked for more details.. D from BC

Far less components to do this with a small microcontroller and capture the timing logic in code. This scheme also allows for far easier inclusion of user control switch inputs, LEDs, and possible other display device such as an LCD module.

- mkaras

i have to use a 555 timer.A simpler circuit which is easy to design.

I don't have much info on that relay activation sequence. Mmmmm checking crystal ball. :) .. I'll guess....

555 astable cct trips 555 monostable 1 to trip relay 1 which triggers 555 monostable 2 to trip relay 2 which triggers 555 monstable 3 to trip relay 3. (Some details missing..) Great if you're really into 555's...

See 555 app notes for astable and monostable circuits.

D from BC

Why ?

The circuit using a microcontroller is definitely easier, as far as the hardware is concerned. Just hook up some controller outputs to the relays (through a transistor) and you're done. You can pick one with built-in RC oscillator, and you won't need any other external components.

If you know how to do it, the software is also trivial. I agree there's a learning curve, but you only need to climb it once. There are many introduction kits which include a small eval board, software, programming cable, and documentation. Get one, play with it during a break in your normal work. Once you're familiar with the tools, you can make simple IO sequencing in a matter of minutes.

Hi venkat,

Try using Cmos Counter CD4020 and a 555 timer as a clock. Hope you can figure out how to drive the relay from cmos IC.

Thanks and Regards,

Bhaskar. venkatsr wrote:

On Usenet, it is traditional to include CONTEXT in your followup post: http://66.102.9.104/search?q=cache:SXIajvWUVHAJ:groups.google.com/support/bin/answer.py=answer=12348+Tempting-though-it-is-*-*-*-*-*-*+remove-*-*-*-irrelevant+STOP+zz+zz+Summarize.what.you're.following.up+BOTTOM+qq+Usenet

Why don't you just include the email address of your instructor? We can skip 1 step and send him the answer directly.

http://66.102.9.104/search?q=cache:SXIajvWUVHAJ:groups.google.com/support/bin/answer.py=answer=12348+Tempting-though-it-is-*-*-*-*-*-*+remove-*-*-*-irrelevant+STOP+zz+zz+Summarize.what.you're.following.up+BOTTOM+qq+Usenet

There is NEVER a time when a 555 is an appropriate solution. Has not been for twelve years.

Use a PIC instead.

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• 5 ---+--------------------+-------------o o---+ | | |> | | | [10R] RY2-2 | | | | | +--->| |---o o------+---+ +----+ | | | | |> | | | | | | | | [RY1] | RY1-1 |[RY2] | [RY3] | --- | | | | | | | | | [D1] [1F] | [D3] | [D4] | | |a | | | | |a Gnd ---+-----+---+---------------+--+---+---+----+

That will do what you said. It uses a 555 timer IC. It contains at least 3 relays. It turns the relays on in a particular sequence:

1, then 2, then 3. It turns the relays off in a particular sequence: 1, then 2, then 3.

You can Google for a 555 circuit.

If this is homework - which it seems to be - I strongly doubt your instructor will give you a passing grade on this *because* it does what you said. If he/she is any good, you'll get a failing grade when you attempt to explain why you "designed" the circuit this way.

If it is not homework, then you need to provide a whole lot more detail as to what you want and why, so that we can give you a circuit that does what you *really* want.

Ed

Hell, for total design and manufacturing costs the uC is probably much cheaper. Tackle your prof with that. Of course if the design objective is working with 555 timer this will not apply.

--
 JosephKK
 Gegen dummheit kampfen die Gotter Selbst, vergebens.  
  --Schiller

yeah, but he'll fail his homework assignment....

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Bye.
   Jasen

yes its an assignment indeed! thnx for all ur replies frends! pls give me more ideas.. Hey ehsjr ! pls explain the circuit u gave !!Thank You !

Ask under the post I made so we can keep the circuit and the explaination together.

Ed