Help with a 3 Button Switching System

Discussion in 'The Projects Forum' started by StuartHenryWilson, Aug 24, 2010.

  1. StuartHenryWilson

    Thread Starter New Member

    Aug 24, 2010

    First off I should make it clear that I am completely new to this. I have no formal training and am interested in learning myself. I have come up with a project which I eventually want to make use of in my house.

    It consists of a water container and a reservoir. The system has 3 buttons, each one powering a solenoid valve for a different time duration and lighting some LEDs. The solenoid valve will release water from the reservoir.

    I've been spending whatever free time I've had reading up on 555 timers and such. It's going pretty slow as I am a complete beginner at this and I don't have much free time anyway.

    I've come up with a schematic which suits my needs - as far as I can tell - but I still have a few questions. Please have a look at the attached image.

    The circuit itself consists of 3 buttons which light the first set of LEDs for a different amount of time each, the second set should come on simultaneously and remain on for approx. 30 seconds.

    When getting to grips with the schematic, for simplicity I left out the solenoid valve that I need. I would like to add the solenoid in series with the first 2 LEDs which will run for the same time as them. Can I simply add that in or will I have to go back to the drawing board?

    I have not even looked at solenoid valves to buy - will the type of solenoid I use greatly affect my design (supply voltage/resistors/etc)? It is important that it runs on battery power so that it is portable.

    The timings for each button are just estimates so that I could visualise the process - I still have to work out the exact values of my resistors/capacitors. Have I made this more complicated than it has to be? Do I have anything where it shouldn't be?

    I am trying my best but I am beginning to feel a little out of my depth. It's time to consult more experienced people than me.

    There is one more stage to the circuit which I will add once I am completely comfortable with the current stage. Any help is much appreciated. Feel free to give suggestions - I am not looking for someone to do this for me, but a point in the right direction would be great.


  2. retched

    AAC Fanatic!

    Dec 5, 2009
    The current required by the LEDs will likely be much less than the current needed for the solenoid. SO, the solenoid could try to draw too much current "through" the LEDs blowing them.

    You can attach them in parallel at the same place. Tap off the main wire in a "Y". Run one end of the Y to your Resistor and LEDs then the other end to your Solenoid.

    You NEED to have resistors for your LEDs or you will pop them mighty quick.
  3. StuartHenryWilson

    Thread Starter New Member

    Aug 24, 2010

    thanks for the quick reply. Please bare with me as it might take me a while to get my head round anything new.

    Should I tap the Y junction into the emitter lead of the transistor?... or the main supply voltage line?

    I have messed around with trying different variations in multisim trial version but I can't seem to get the simulation to work for any other arrangement. When I add resistors in for my LEDs the transistor fails to trigger my last 555 timer. The same thin happens when I add my solenoid.

    Do I have any resistors where I do not need them or will the transistor protection resistors have an effect on this? I just chose them through trial and error with the simulation - I opted for the highest value that would allow both sets of LEDs to function - I am keen to get the current flow as low as possible when no switch is pressed as I do not want the battery to drain.

    Your advice is much appreciated - thank you.