Railroad Crossing Flasher Using a 555

[kf4jqd]

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.

Andy

 

[Frank Cullen]

andy,

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

73's

WB8JWE

 

[kf4jqd]

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.

73,

Andy KF4JQD