Bathroom Spray 10 seconds ON on Demand switch

Discussion in 'General Electronics Chat' started by rvenki76, Mar 1, 2013.

  1. rvenki76

    Thread Starter New Member

    Dec 6, 2008
    I’m a beginner. I’m designing a 10 seconds ON timer like circuit to drive the Motor of Bathroom Spray (I’m testing with LED as of now).

    I found some delay on circuit and added 1 more TR to have inversion (see the attached pic).

    I played with the R1, R2 & Caps to get 10 seconds ON after a long struggle.
    But, when I switch OFF and ON the circuit next time, the LED is ON only for 3 seconds (caps already has some power). It depends how long I wait after OFF, for caps to discharge via R2.

    But, my requirement is to get ON for 10 seconds all the time without even waiting. I tried a lot and failed to achieve what is needed. How can I get same 10 seconds LED ON and OFF after that till I switch off & ON again.

    I realized that R2 must bigger than R1 or else caps wont charge enough to trigger T1.

    Please help me to have it with few components. I wonder if I can get it with 555.

    Thanks in advance
  2. ScottWang


    Aug 23, 2012
    The circuit that you designed is just for the LED, but it can't be used for the Motor, because the motor will needs more current, so you have to measure the current of the motor.

    You want to try the LED is fine, that is one kind of learning.

    1. The switch change to push button switch, when you press the switch then the switch is on, it will become off when you release the switch.

    2. Remove the TR1 and R3.

    3. Moving the Ground of R2(100K) and connecting to B of TR2.

    4. Increasing the values of CE(10uf) and R2

    5. Reduce the values of R1 less then 1K.

    That is just for the LED testing.