Introduction / Guidance from the Experts

Discussion in 'The Projects Forum' started by brandolph, Sep 12, 2009.

  1. brandolph

    Thread Starter New Member

    Apr 5, 2008
    Hello all,

    My uncle, a Midwest farmer, has been attempting to construct a basic system for use on a farming implement after failing to find something similar he could purchase. He acquired all of the individual components and then contacted me when they failed to “perform as expected”. Unfortunately I am a mechanical engineer and have very little experience with this type of electronics.

    His Proposal:

    A visual and audible safety warning system powered by a tractor’s 12VDC supply. The circuit is activated/deactivated via a NO magnetic reed switch. When the switch is closed, 8 LED’s and a buzzer are energized and remain so until the magnets proximity to the switch surpasses its operating distance. The circuit also contains a rocker switch enabling the system to be manually deactivated regardless of the condition of the reed switch.

    He previously purchased standard LED’s and was attempting to make them flash when activated. I suggested he simply acquire flashing LED’s to simplify the design, which he has done. If this was an uneducated suggestion, please let me know.

    My (His) Request:

    Conversations with him seem to indicate that he was most likely able to assemble a fully working design with the exception of the LEDs. He said he was able to get one LED with a resistor to function, but not at the required 12 volts. At full voltage, he said the LED would switch from a flashing state to on but no longer flashing. The LED’s are 3.5V/20mA and the alarm is 12VDC 18mA(max.). I unfortunately could offer him very few suggestions but told him I would find someone who could. Given that this will function as a safety device, I would very much like to see it work for him.

    I have attached a very rough Visio generated drawing representing all known components organized in the way he “wants” his final design to appear. If any portion of this layout is unclear, I will be happy to provide clarification. I would very much appreciate any direction I could offer him based on your suggestions. Any visual aids that would prevent translation errors between me and him would most likely be very helpful.

    Thank you in advance for any and all instruction offered.
    Last edited: Sep 13, 2009
  2. williamj

    Active Member

    Sep 3, 2009

    Welcome, I have just recently joined myself and would like to help if I could. However, it's is unclear as to what your uncle wants to be warned about. Is it tractor roll over or an implement being towed by the tractor breaking free?

    Knowing the type of warning could be a big help.

  3. brandolph

    Thread Starter New Member

    Apr 5, 2008

    Thanks for your reply.

    Initially, he is using it on a type of trailer used to pick up and transport round bales. However, if he is able to get it working, he would like to be able to use it for multiple applications where proximity changes occur, thus the reed switch.

    I worked on it with him via the telephone yesterday for several hours and have possibly made some progress. We were able to get multiple LED's working, but noticed that the flashing was not synchronous. I'm not sure if this is due to slight manufacturing differences in each LED or is circuit related. My suggestion to purchase flashing LED's may have been incorrect.