Activating switches in sequence.

Discussion in 'The Projects Forum' started by nathan01, Dec 30, 2006.

  1. nathan01

    Thread Starter New Member

    Dec 30, 2006
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    Hey, im trying to make a circuit to activate 3 switches in sequence.

    I want the whole circuit to be activated by one switch that i press once to start the process.

    Firstly i want switch one to close and reopen. Then i want S2 to close and reopen. Then i want S3 to close and reopen. Then i want the process reset.

    The thing that complicates it is that the time between s1 and s2 is to be approx 0.2 secs. This is the same for s2 and s3.

    Now i have brought myself a 555 timer kit with a bunch of circuits, yet my limited knowledge means i cant utilise it.

    I have done a university unit on elec eng, but it focused on theory, and i dont know how to design circuits.

    So if anyone knew of a circuit that would do this for me i would greatly appreciate it.

    Thanks alot.
     
  2. Gadget

    Distinguished Member

    Jan 10, 2006
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    Check out the 4017 CMOS decade counter chip.
    Use your 555 timer to generate the clock pulse and use either the 1st 3 outputs (out1,2,3 buffered via a transistor to each relay..... no gaps), or every 2nd(1,3,5) or 3rd(1,4,7) or 4th(1,5,9) output (up to 3 outs) for a longer gap in the sequence (1,2 or 3 times the length of the ON time). Hold the reset pin high to stop the 4017 counting and reset the sequence, and pull it low to start the sequence.
    You could even have output "0" holding the reset pin high with a NC mom action switch in the line so the switch doesnt have to be held down (remember to make sure a pull down resistor is installed so the reset pin doesn't float). The count enable switch should be tied to 0 volts.
    For a longer relay "On" time, connect outputs 1,2, to the first buffer via 3 diodes, 4,5, to next, 7,8, to next (via diodes). This will give a relay ON time of 2 times the gap time

    You don't mention what the "ON" time for each relay is.... if its longer than .4 second, then a slightly more complex circuit is required..
     
  3. nathan01

    Thread Starter New Member

    Dec 30, 2006
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    Each button/switch is only to be pressed for a fraction of a sec, maybe 1/20 of a sec.

    The set i have with the 555 timer has a bunch of circuits that i can make with it, its a kitset with a prepared board. I tried looking in the manual for information on the clock pulse, but i dont think it is included. Could you refer me to somewhere for further explaination.

    Also, you say using the outputs of the timer to set a relay, would this relay be the device that closes the switch, if so 1/20 of a sec shouldnt be a problem.

    Does this clock pulse send a pulse to pin 1, 2 and then 3. Sorry if im asking stupid questions.

    Thanks
     
  4. nathan01

    Thread Starter New Member

    Dec 30, 2006
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    Wait i think i get this a bit more, use a 4017 cmos chip to produce the sequence, however the 555 produces the pulse to the CMOS.

    What waveform would i require the 555 to produce? Maybe a monostable, one square wave pulse??

    Would that be enough to put the sequence around once.

    Then would i attach the outputs from the CMOS through a relay, or through a transistor, in order to close the switch?

    Thanks...
     
  5. Gadget

    Distinguished Member

    Jan 10, 2006
    613
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    Your getting there. Use the 555 in Astable mode to generate a squarewave with a period of .0666mS. This is the clock for the 4017
    Connect the reset pin of the 4017 to a 100k pulldown resistor, and also to one side of a NC switch. Connect the other side of the NC switch to output "0" of the 4017. Connect the clock enable to ground.
    Connect output "1" to a buffer transistor then to relay number 1 (switch 1 contacts)
    Connect output "5" to a buffer transistor then to relay number 2 (switch 2 contacts)
    Connect output "9" to a buffer transistor then to relay number 3 (switch 3 contacts)

    Output "0" is high in a reset condition, which in turn is used to keep the 4017 in reset condition via the NC switch to the reset pin. Momentary activation of the NC switch lets the reset pin go low via the 100k pull down resistor which starts the sequence.... out 1 (relay1 for 1/15 sec) out 2 (nc) out 3 (nc) out 4 (nc) ...... ie a pause in relay ops for 1/5 second...... out 5 (relay2 for 1/15 sec) out 6 (nc) out7 (nc) out 8 (nc) .... ie another 1/5 sec pause in the relays......... out 9 (relay 3 for 1/15 sec).......... then back to the start with output "0" putting the system back into the reset state.
    Will make up a circuit if I get time....


    [​IMG]
     
  6. nathan01

    Thread Starter New Member

    Dec 30, 2006
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    Thanks alot for your expertise, ill experiment with this circuit.


    Im hoping i can get the IC 4017 from say dicksmiths, or otherwise ill have to order from online. Ill keep you posted on how i go....

    *** I have made the 555 side of the circuit, and i ran it from a 9V battery. I measured a AC voltage from pin 3 to ground of about 0.7V, does that sound correct or in an acceptable range??
     
  7. Gadget

    Distinguished Member

    Jan 10, 2006
    613
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    You kinda need a scope to see the output off the 555...... if it is a true square wave (the values I gave you should make it close) then the AC output should be around 9v peak to peak AC, which would equate to something like 4 to 4.5 volts measured on a regular multimeter switched to AC and coupled to the output via a capacitor.

    Yup, Dick Smiths or Jaycar will have em. Common as, and probably under a buck each.
    If your gonna experiment, then use an IC socket as well..... Just in case.....
     
  8. nathan01

    Thread Starter New Member

    Dec 30, 2006
    6
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    Im going to keep on going with this, however the relays and such make the circuit board rather big. Seeming it is meant to trigger buttons in a controller.

    I have actually spoken to someone who has used a picaxe 08M to do it. and he said it worked well.

    how much knowledge do you have of these devices, and maybe in application to this? im going to do some research on it now.
     
  9. Gadget

    Distinguished Member

    Jan 10, 2006
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    Yup, or even the slightly cheaper PICAXE 08.... as the extra memory and analogue functions of the "M" version isn't required.
    I Use them for LOTS of stuff, but didn't suggest as wasn't sure if you have any programming knowledge (or the desire to learn the simple codes).. you would also need to build up a simple programmer (although they can be programmed in circuit with a special cable) and download the software... and also you seemed to be after relay outputs. The PICAXE also works at 3 to 5 volts.
    What are the switches actually switching..... is a simple "Hi Low" ttl style output ok... or perhaps even the low voltage/current switching ability of the 4066 may suffice ???

    goto www.picaxe.com and see if they are what your after. I can help you out with them if u like.
     
  10. nathan01

    Thread Starter New Member

    Dec 30, 2006
    6
    0
    Ive done a bit of learning, im a quick learner, and i think i have made some code that my do the job. Im going to email you what i have because its easier.
    Thanks
     
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