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Rotary Switch to Variable Timing Circuit?

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  • Rotary Switch to Variable Timing Circuit?

    I need some EE help with a project I am trying.

    What I need is a timing chip whose time(s) are set by rotating a dial.

    Set the dial to 1sec. When you power the circuit (switch) you get a 1sec pulse of power to the output and then it stops.

    Im looking to have a 10-12 position rotary dial connected to a timing chip. How the hell do I go about even starting this project? How does one get EXACT timed pulses from the I need to program it?

    I need non-crazy times like 1s, 1/100th, 1/1000th etc.

    So, to reiterate my ranting unintelligible self:

    set dial to a certain time
    power on the circuit
    timing chip reads setting on dial and outputs appropriate amount of time in a power pulse

    This will allow me to turn on/off a device with perfect timing I can set.

    HELP!? Are there things already set up like this? Do I need to get a programmable chip and dev board?
    (All done)
    iPad Mini 128GB, RF 600.5 amp, JL12W0V2, 8 Infinity Components

  • #2
    It all depends on the accuracy & delays you need.
    A 555 timer is analog and uses resistor-capacitor combinations for fractions of a second to many 10's of minutes.

    Otherwise there are programmable timers - check Jaycar.

    Then there's the FB, Arduino, etc.


    • #3
      Yes, the 555 Ive researched quite a bit. But, unfortunately if it requires different sets of res/cap for each setting on the rotary dial, it defeats the purpose of my project. Itll be too large for the small containing space.

      I was hoping for a rotary dial which sends different "signals" for each different setting. Hexadecimal seems the only way to accomplish this because the 555 is the only other way, and using a normal switch between res/cap banks, isnt gonna cut it. A chip would read the "signal", i.e. setting, and output a pulse of power for a specific length of time.

      Using a dev board, unless it lets me take some chip off and install it as I just described...will again be too big and much overkill.
      (All done)
      iPad Mini 128GB, RF 600.5 amp, JL12W0V2, 8 Infinity Components


      • #4
        I reckon forget the coded switch.
        It's the timer that will do the decoding (as per normal practice (for single-users)).

        Maybe consider a digital up/down rotary instead (1+3 wire) so you don't need 1+12 inputs (or 1+4 bits) etc.


        • #5
          I believe this is going to call for a programmable microcontroller I can feed input from a switch and output timed pulses...but what chip, how to program, who knows!!!?
          (All done)
          iPad Mini 128GB, RF 600.5 amp, JL12W0V2, 8 Infinity Components


          • #6
            Well you could go with Arduino, they're cheap, and if you know C, you know how to program one. They're fairly easy
            "stop with the REINSTALLS, what do you think we got some lame-o installer!!!" - mitchjs
            My Shop


            • #7
              That was gonna be my recommendation.
              Cheap, and with common open source information.

              But I prefer uPCs over PICs anyhow....

              (And I still prefer assembler LOL!)


              • #8
                But a dev board is gonna be too big. I need, literally, like a 555 chip thats not analog but programmable.
                (All done)
                iPad Mini 128GB, RF 600.5 amp, JL12W0V2, 8 Infinity Components


                • #9
                  Build your own PIC (8 pin)
                  Or use a Stamp uPC.

                  There are digital chips that can count down from a binary value. But then you have the problem of providing the binary value....
                  You can use ordinary rotary switches with enough diodes - but do you really want that?
                  Hence a PIC to do the binary, in which case it may as well do the timing - ie, the lot.


                  • #10
                    So, I can have a rotary switch, hexadecimal, which feeds values to a PIC and the PIC then pulses for a set period, sending power to another circuit for that period.

                    Dont suppose youve got a direction I could be looking for parts and a programmer?

                    The resistor bank with a ordinary switch has been tried, and while I am currently working on it to get it small and into the compact space where this goes, I wanted something less analog.
                    (All done)
                    iPad Mini 128GB, RF 600.5 amp, JL12W0V2, 8 Infinity Components


                    • #11
                      Bad luck - analog is usually smaller. EG compare a binary switch (4 bits = 5 wires) to a 2-wire analog... (for 12 positions).

                      I see way too many options to be able to recommend or suggest a direction...
                      Digital data books (National CMOS etc) for discretes. PICs & PICAXES. uPCs & CPUs.
                      The programmer then depends on what is chosen.

                      Good luck.