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Need help with a simple circuit

Discussion in 'General Electronics Discussion' started by Kerrigan, Dec 31, 2013.

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  1. Kerrigan


    Dec 31, 2013
    Is there a design for a simple circuit that will sense a 0.5v DC current which can rise to 18v DC and use that to turn on a 9.5v current?

    The DC current will switch polarity depending on direction (turns a motor clockwise or counterclockwise) to it would need to account for that aspect.

    Basically turn the controller to ramp up the DC current from 0.5v to a maximum of 18v which will switch the 9.5v current on and keep it clamped until it again drops below 0.5v DC.

    It is to activate a sound module and have it turn off when the activity stops.

    Thank you!!
  2. davenn

    davenn Moderator

    Sep 5, 2009
    hi Kerrigan
    welcome to the forums :)

    0.5V DC is a voltage not a current, so the voltage can vary between 0.5 and 18V ? is this a continuously varying voltage or does it just step straight from 0.5 and 18V ?

    Do you want it to turn something else on ONLY when it gets to 18V or what ?

  3. Kerrigan


    Dec 31, 2013
    Yes, it's a controller running a motor which turns a model railroad turntable. It has an optional sound module I'd like to activate when the voltage that drives it starts out at about 0.5v and as I turn the controller up to increase the speed of the turntable motor it can rise as high as 18v until I stop it by turning the controller back down to 0v. It is reversible so the polarity will change as the turntable move counterclockwise, or clockwise.

    So I'd like the sounds, which are activated by a separate 9.5v power supply.transformer to come on when the motor starts turning and turn off when it stops.

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