Need simple circuit help

Discussion in 'General Electronics Chat' started by jimmynorth, Jan 19, 2015.

  1. jimmynorth

    Thread Starter New Member

    Jan 19, 2015
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    Hi new here. I have a project that has many 6v lights on a simple circuit. I need to add a way to complete a different circuit when a light comes on or voltage is sent though the line.
     
  2. joeyd999

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    Use a relay?
     
  3. jimmynorth

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    Jan 19, 2015
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    Was thinking that. Is that the simplest methed? Or is there a chip that will act like a relay?
     
  4. WBahn

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    When any of the lights go one? Or a particular light goes on?

    Are these many 6V lights on a single switch?

    Do you want to complete the other circuit only if the light actually comes on, or just when it's supposed to come on (in other words, if the light is burned out but it is switched so that it should go on, do you want the other circuit to complete or not)?

    What do you mean by "or voltage is sent through the line"?

    Could you sketch of a schematic, even if just in Paint or hand-drawn and scanned, so show what you have and what you want?
     
  5. darrough

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    Jan 18, 2015
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    A bjt transistor
     
  6. jimmynorth

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    Jan 19, 2015
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  7. WBahn

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    Okay, that's a start. Thanks.

    Now, do you want to close the switch in the right hand circuit only when that right-most bulb is one, or when ANY of the bulbs are on?

    What do you want to have happen if the switch is closed to turn on the bulb but it is burned out? Should the switch close or not?
     
  8. jimmynorth

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    Jan 19, 2015
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    Yes each left handed bulb will have its own event action just like the bulb on the end. I have a sound board I want to hook up to each bulb so when that bulb lights up it will complete the circuit on the sound board trigger for that sound. The sound board is a stand alone board that if I make ground to a assigned pin it will make that pins sound. So pin one is bulb one. Pin two is bulb two. Ect. I was thinking photodiode but that only works if the bulb is allways good.
     
  9. WBahn

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    I was thinking photodiode as well, but from your last comment it sounds (no pun intended) like you want it to work even if the bulb is bad.

    A relay or optical coupling has the advantage that you don't have to worry about properly ground referencing the two boards to each other.

    How many bulb are we talking about?

    Is it a one-to-one mapping between the bulbs and the sounds? In other words, is there ever a time when you want two or more bulbs to play the same sound?

    One option is to use optocouplers -- they are made specifically for this kind of thing.
     
  10. ScottWang

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  11. jimmynorth

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    Jan 19, 2015
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    Was thinking 10 would play the same sound. As each bulb is on sequence after each other. They are score points lights for a pinball machine.
     
  12. darrough

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    Jan 18, 2015
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    Please see the attachment. Would this work?
     
  13. jimmynorth

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    Jan 19, 2015
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    Small question. Dose a photo diode produce any electricity when on? Some info makes them sound like a mirco solor panel.
     
  14. jimmynorth

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    Jan 19, 2015
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    I
    I don't think it would due to the grounds on each board are separate. Would like to keep the two isolated in fear of one killing chip on the other. The main board that is the country board was made in 1980 and some chips are next to impossible to find replacements for. Cost wise the photodiode could be my best bet.
     
  15. WBahn

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    Then what you can do is do it two stages. For all of the buttons that are to play a given sound you use a "wired-OR" arrangement in which any one of the group can make current flow in the input of the optocoupler. Then each optocoupler output is wired to activate one of the sounds. That makes it possible to have arbitrary arrangements in which, say, Light A makes Sounds 1 and 3 while Light B makes Sounds 2, 3, and 5.

    If that's of interest then we can flesh it out.
     
  16. WBahn

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    The produce a tiny amount, but the better way to view them, for most applications, is a light controlled resistor. You put them in a circuit so that they are reverse biased. Normally this would mean that no current (other than some tiny leakage current) flows. As light impacts the diode it allows some current to flow "backwards" through the diode. The more light, the more current that can flow. In a switching optocoupler you have an LED and a photodiode (or phototransistor, same basic idea) within a package so that when you pass current through the input LED the light from it makes the output side appear as a relatively low resistance to the circuit that it is a part of.
     
  17. jimmynorth

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    Jan 19, 2015
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  18. WBahn

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    A photoresistor will have the problem that if the bulb is burned out the sound won't play. You implied that this wasn't what you wanted. Also, this means putting the photoresistors near each light and making sure than even if all of the other lights are on that the photoresistor doesn't get enough light to activate the sound if "its" bulb is off.
     
  19. ian field

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    Oct 27, 2012
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    You could use a series silicon diode to drop just enough voltage for the B/E junction of a transistor, this can sense one or any number of the lamps drawing current.

    Another approach is to wind a coil round a reed relay, but the lamps need to draw a decent amount of current for this to be easy.
     
  20. jimmynorth

    Thread Starter New Member

    Jan 19, 2015
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    Thought about the reed relay but I think I may go with the photo resistor. Thanks all for your help.
     
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