Jumper bypass - stuck on diodes

Discussion in 'General Electronics Chat' started by bobpombrio, Jul 21, 2016.

  1. bobpombrio

    Thread Starter New Member

    Apr 7, 2014
    3
    1
    I am trying to bypass a set of fixed jumpers that will eventually be fired from a rotary switch. I've been messing around in Virtual Breadboard and have hit a wall. I am trying to have it that when the button is pressed that it only lights up the led, via the relay, that the wire goes to. Since I don't want reverse current flow I put each set of inputs on a diode. But nothing is working, I tried reversing the diodes with the same results. Without the diodes then everything lights up when any single button is pressed, because of the reverse current flow.

    Help please! I'm not a EE or properly trained, I'm a software guy who is self taught on circuits.

    [​IMG]

    Thanks,
    Bob P.

    PS. Oh I'm using the relays because they will complete a circuit when energized. The LED's are just for this testing.
     
  2. crutschow

    Expert

    Mar 14, 2008
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    You need to post a circuit diagram of what you are trying to do.
     
  3. dl324

    Distinguished Member

    Mar 30, 2015
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    Welcome to AAC!

    Post a schematic of what you've breadboarded.
     
  4. BobaMosfet

    Active Member

    Jul 1, 2009
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    In a schematic, it would make more sense to label the inductors as 'L1, L2, and L3' since 'L' is the letter for inductors (which is what a relay is in this case), whereas 'R' is for Resistors.
     
  5. BobaMosfet

    Active Member

    Jul 1, 2009
    109
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    The first mistake I see in your breadboard, is that one side of each LED isn't connected to anything other than the relay. The other side of the relay goes nowhere, so the LEDs will never light.
     
  6. BR-549

    Well-Known Member

    Sep 22, 2013
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    It's because the diodes are connected to the same point. Straddle the non relay side tie points.

    Did I say that right?
     
  7. bobpombrio

    Thread Starter New Member

    Apr 7, 2014
    3
    1
    Thanks for the labeling suggestions. The base layer is a breadboard so connections are made to the column. If I knew how to do a schematic I'd post that as well.

    The idea is to replace a set of jumpers, 3 to be exact, with a multi position rotary switch.
    1 2 3
    . . .
    . . .

    configs are:
    1. all open
    2. 1 closed 2,3 open
    3. 1 open, 2 closed, 3 open
    4. 1 closed, 2 closed, 3 open
    5. all closed

    I want to use a rotary switch to make the selection, so I want to have the switch energize a relay that would perform the operations of the jumper. So 3 relays, one to a jumper, that when energized they close the jumper. The first 3 configs are easy, it's the 4th and 5th that are giving me fits.

    The problem is that I am activating all of the relays at once, because of the 5th (and 4th) configurations.

    Any suggestions on how to only effect the relay that the wire goes to and not back flow would be appreciated.

    Bob P.
     
  8. BR-549

    Well-Known Member

    Sep 22, 2013
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    392
    Isolate the non relay sides of the diodes. Hello.
     
    GopherT likes this.
  9. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Don't put the anodes of all of your diodes in the same column of the breadboard. All of the diodes are in parallel right now so there is no reason to have more than one (in the current configuration). Your strategy is correct, diodes should work, you just assembled your breadboard incorrectly. Pick a different column for each diode (anodes) and try again.

    Then, look at each LED (connected to + supply). Then follow to the Resistor connected to the LED. And the Relay (Switch) connected to that resistor. Then the far side of that Relay (switch), there is NOTHING! You need to connect those Relay (switch) pins to ground.
     
    Last edited: Jul 21, 2016
  10. Tonyr1084

    Active Member

    Sep 24, 2015
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    Tripple Relay Swtiching.png

    Keep in mind that each diode will drop about 7/10 of a volt. If you're running a 5 volt system, in config #5, you're dropping about 1.4 volts, meaning your relay will only see 3.6 volts. That MIGHT NOT be enough to turn on relays 1 & 2.

    Oh, and I neglected to draw in the power feed either. It goes to the center point of the rotary switch.
     
    Last edited: Jul 21, 2016
  11. BR-549

    Well-Known Member

    Sep 22, 2013
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    "Then, look at each LED (connected to + supply). Then follow to the Resistor connected to the LED. And the Relay (Switch) connected to that resistor. Then the far side of that Relay (switch), there is NOTHING! You need to connect those Relay (switch) pins to ground."

    Doesn't that get connected thru the center relay contact, which comes out the back of relay?
     
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  12. GopherT

    AAC Fanatic!

    Nov 23, 2012
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    Maybe, I don't have my glasses and that image doesn't zoom on my ipad.
     
  13. Tonyr1084

    Active Member

    Sep 24, 2015
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    For those of you who didn't spot it - the relay is a SPDT (I think that's right - one common, one normally open and one normally closed). The far left side of the relay is the common pin and is connected to ground. It's the NC that is not connected to anything.
     
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  14. bobpombrio

    Thread Starter New Member

    Apr 7, 2014
    3
    1
    Thanks every one for all of the help and suggestions.

    But.... (you knew it was coming be honest!!)

    I'm going a different route. See I decided to do all of this with a Arduino, actually just the chip I don't need all the other "crap" that comes with it it. The added bonus is that I can have a display showing what the switch it set for, also once the machine is started it will ignore any changes.

    Hey what can I say? I'm a software guy by trade with enough knowledge of electronics to get in big trouble at times.

    Bob P.
     
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  15. BobaMosfet

    Active Member

    Jul 1, 2009
    109
    11
    I don't think so. If you look at his breadboard drawing, the LEDs cannot light because they aren't connected to ground on the other side of the relay. The diodes connect to a _different_ point on the relay (per the drawing).
     
  16. Tonyr1084

    Active Member

    Sep 24, 2015
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    Hate to bang this drum again, but the relay IS connected to ground. LOOK CLOSER!

    Relay Board.png
     
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