Newbie to electrical circuits

Discussion in 'The Projects Forum' started by mwturnquist, Feb 5, 2016.

  1. mwturnquist

    Thread Starter New Member

    Feb 5, 2016
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    I am pretty much a newbie when it comes to component design so I am asking for help in determining if what I want can be done with smaller components.

    Below is a basic layout of a circuit I would like to construct.
    - I have 4 push buttons in 3 different locations
    - Each location needs to be able to be operated independently and not tied together with other locations
    - Three 4PST relays in the normally open state are used and powered on individually by a selector switch giving a particular control location operation control.
    - Each location will be less than 10 meters from the motors
    - The amount of current at each dry contact will be <1mA

    While the drawing below only uses 4 dry contacts per location the final design will require 24 dry contacts
    What I want to do is not use relays but an IC instead. I want the circuit that powers the switching to be isolated from the switching.
    So my newbie question is....
    Can an analog IC switch be used in place if the relays?
    Is there a recommended product?

    Thanks Mike
    [​IMG]
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,969
    744
    Your relays are wired wrong, they operate all four positions at the same time, if your looking to replace the contacts with an IC try a CD4016, CD4066 quad switch, but they won't be able to drive the motors, just power the relays.
     
  3. ScottWang

    Moderator

    Aug 23, 2012
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    When the 4 dry contacts expanding to 24 then how are the 4 push buttons in 3 different locations?

    You could using CD4066 and refer to --
    Two Sets 10 channels O'scope and Multimeter Multi-Inputs Selector.
     
  4. mwturnquist

    Thread Starter New Member

    Feb 5, 2016
    2
    0
    I think I over complicated my question by trying to simplify it. The drawing is a fabrication of a project I wish to do. I am going to just ask this as a question.

    Is there an IC switch that can be used in place of a mechanical relay. It can have from 1 to xxxxx individual switches or contacts. The final design will require 24 switches using however many IC's it will take to accomplish this.
    - The current flowing through each contacts/switches will be less than 1mA.
    - The control for the switch needs to be on its own power rail much like the coil in a relay and operate using 5v-12vdc.

    I hope this helps clarify
    Thanks for help, low voltage circuits is all greek to me.
     
  5. ScottWang

    Moderator

    Aug 23, 2012
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  6. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    In general terms there are two types of switching or selecting IC's. First is an analog switch. This is an electronically controlled series resistor that goes from a very high value to a very low value on command. This is the closest thing to an actual relay because there is a direct galvanic connection between the input signal and the output signal - no buffers, gates, level translators, etc. However, unlike a physical relay it has more limitations on the signal voltage range, and usually the amount of current it can pass is pretty low.

    The second kind is a digital multiplexer. This is an arrangements of gates that directs a logic state (1 or 0) from an input pin to an output pin on command. The input signal is reconstructed at the output, so something that is 3V at the input might be 4.5 V at the output.

    If you are switching control signals to the 4 "MOVE" inputs in your drawing, then the logic gate approach will do what you want with the fewest components and least hassle. If you are switching the actual motor power, that is a very different problem. Yes it can be solved with all solid state components, but we need to know a lot more about the signals (voltage, current, etc.).

    ak
     
  7. ScottWang

    Moderator

    Aug 23, 2012
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    ...each contacts/switches will be less than 1mA.
    So it should be just a control signal of motor part, otherwise the described was wrong.
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    2,367
    Yes, a PLC!;)
    Or in this case a Smart Relay should do it.
    Max.
    [​IMG]
     
  9. AnalogKid

    Distinguished Member

    Aug 1, 2013
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    In your drawing the common for the movement switches and the common for the selector switch are not connected. For electronic switching using anything other than optocouplers, the controls and signals must chare a common power reference.

    ak
     
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