Railroad Crossing Flasher Using a 555

Discussion in 'FAQs' started by kf4jqd, Sep 3, 2006.

  1. kf4jqd

    kf4jqd Active Member

    Hi Everyone:

    I have made this neat little rr crossing flasher with a 555 timer chip. I would say the project is mediate for people. Here's some things I have done. R1 and R2 I used 10k resistors. For R3 and R4 I used 450 Ohm resistors. Here's a neat little trick too. On the output, I used 2N3904 transitor. This enables you to use light bulbs! If you add a relay to the transitor, you can even switch higher voltage and current! Here's some pictures.


    Attached Files:

  2. Frank Cullen

    Frank Cullen New Member


    How is the transistor and relay connected? Not clear in diagram.


  3. kf4jqd

    kf4jqd Active Member

    Hello Frank:

    I added where you should connect the transitors. You will need one PNP and one NPN transitor. If you use a high power switching transitor, you may not need a relay. I also showed where to add the power and relay to the trnasitors.


    Andy KF4JQD:wave:

    Attached Files:

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