Building Flasher Circuit

Save yourself a whole lot of trouble by going to Dalee Electronics. They have built up flasher circuits that will operate either regular bulbs or LEDs. They are reasonably priced as well. (No, I don't work for them, just like and use their stuff.)

Chris

LVHR

I'll put in a plug for Evans Designs as well, they sell some interesting LED systems. For the alternating flashing lights on a crossbar a 455 timer would be easy enough (and adjustable).

If you can't find what you want, email me and I'll get back to you with a circuit.

If you like the challange of "building your own", as opposed to buying a circuit preassembled, look for a book titled "Easy Electronics Projects For Toy Trains" by David E Greenwald.  It has exactly what you are looking for.

Check this page: Model RR Electronic Circuits

Here is the Dual Alternating Flasher Circuit that will do the flashing lights.  It uses power transistors that will flash almost anything, you could also use smaller transistors for a single bulb in the dual signals.  I suspect the 2N3055's would probably drive half a dozen signals.

Here is the IR Train Detector that you can build to detect the presence of a train.

Here's a board from WEHONEST on eBay.  IR/Magnetic Presence Detector

I bought some of these, they come with IR and reed switches so you can do block detection using IR or a magnet in your trains.  The magnetic option is good if you only want a specific train or two to activate the signal or other device.

Thanks gunrunnerjohn,

Yes, I do enjoy trying these building projects. These will be intersting for me to try. One question, and with your backround this may be simple for you to answer, can the flasher timing be made adjustable by adding or changing a component?

Thanks

Ray 

Yep, change the 470uF cap value to change the flash rate.  Changing the 39K resistor would also change the flash rate.  I haven't tried that circuit, but it sure is simple enough.

Note that the lamps are part of the circuit, so this one won't run without the lamps in place.  It's also not really suitable for LED use, it was designed for incandescent lamps.  There are many other similar circuits using the NE555 that will work for LED signals.

I dug this out of the archives, from about 30-35 years ago.

Bill

Looks very similar to the previous one I posted, just uses more parts.

Get an NE555 from Radio Shack.There is a simple formula

for what resistor and capacitor values to use for the frequency

of flashing you want. Picking resistor values will get a

square wave output and both LEDs can be driven directly from

the 555 output.

All Electronics sells a $5 kit that flashes 2 red LED's.  The kit is currently on backorder but should be available at the end of July.   Here's the link"

http://www.allelectronics.com/...D-FLASHER-KIT/1.html

Check out Rainbowkits.com.   They have an assortment of electronic kits, including the Blinkey for $3.95.  Also sell LEDs in quantity and resistors $1.50 for a Pack of 100.

This is a simple 555 circuit. Might also work with light bulbs. See the PDF schematic on the site. Power it with a 7812 regulator circuit for bulbs or a 7809 etc. for LEDs.

I have a circuit in my note book which is a little bit different,does the same thing. An alternative is to use a single flasher and power a relay coil instead,then power the bulbs with capacitor discharge with the contacts. Gives a cool flashing effect for light bulbs.

Dale H

The "blinkey" kit only has one "flaw"--- the leds will not be on for the same time-- the circuit as built will have one led on for 1/3 the other on for 2/3 of a cycle. Real crossing warning lights use a 50% duty cycle. To fix this circuit to generate a 50% duty cycle, all that needs to be added is a 1N4148/1N914 diode across the R2 resistor. The cathode(the end marked with a band) of the diode must be connected to  the cap/resistor junction.

 The Diode in effect shorts out the R2 resistor during the IC's charge time, and as long as the R1 and R2 are the same value, you will get a 50% duty cycle.

The resistors are not the same value.  I think you could accomplish the same thing by adjusting the values of the resistors and/or caps.  I haven't put this together to see...

This one looks pretty flexible, it has pots to adjust each LED flash rate.

For a square wave output, make R1 much smaller than R2.

Set R1 to 10K then with R2 = to 2.2 Meg and C= to .1

each LED will be on for .15 sec. If you want to change

the flashing rate use the formula t=.693* R2 *C with R1

mush smaller than R2.

For a crossing flasher, I'd probably bump the times up around 5-10 x over the .15 you mention.

Hey to all you folks,

I have no excuse now not to get one of these going, as a matter of fact I want to try a couple different circuits to see which I would prefer.

Thanks for all the replies, this OGR is a great place to be

Ray