Blinking LEDs!
#1
One of my teenage hobbies was electronics. I used to make small electronic gizmos for use on my railroad, including transistor throttles and crossing gate flashers. I used to use a small 8-pin integrated circuit to build simple oscillators to control LEDs.

For a recent (non railroad) project, I learned they now have blinking LEDs! Basically, you just hook wires up to it, and it blinks! for all non-electronics whizzes out there, there are a few possibilities for some basic model railroad eye-catchers. Perhaps FREDs, a blinking light on a tower, signals, highway signs...
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#2
I saw some blinking LEDs on Ebay. The specs said they had to have a 5 volt power source and that you couldn't put a resistor in series with it. That seems strange, but perhaps the varying current and the mini-electronics require that? Did you happen to look at the specs on the ones you saw?
Three Foot Rule In Effect At All Times
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#3
The one I got is actually a radio shack part. I would assume the ones you saw on ebay were designed to run on a 5v ttl power source.

<!-- m --><a class="postlink" href="http://www.radioshack.com/product/index.jsp?productId=2062553">http://www.radioshack.com/product/index ... Id=2062553</a><!-- m -->
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#4
Blinking LED's are not that new. I had bought a batch of them a good 15 years ago along with some other surplus parts. I seem to remember though, that they were the larger, T1 3/4 size. I didn't have a use for them, so I sold them to an electronic dealer at a slight profit. They apparently sold well since he called me later on and wanted to buy more. And yes, they do have a flashing circuit in them an so they do require a constant voltage source like most any circuit.
Don (ezdays) Day
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founder of the CANYON STATE RAILROAD
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#5
Yes indeed they are not that new. Resistors can be used however. Just work out a matching value for your LED. If it is a 5V version, and you have a current rating, then depending what your power supply is, will determine how big your resistor needs to be. Let's say the led draws 30mA, and your supply is 12V, this means your resistor has to soak up the remaining 7 volts (12-5=7V). Your resistor then needs to be:
R=U/I equals 7V/30mA = 7 / 0.03 = 233 ohms. However, this value is not commercial available, so get the next value up from your supplier, depending on whether it is a metal or carbon resistor, you may find the value varying somewhat. ( a standard 5% carbon E24 resistor range would be 240 ohms) For more on resistor ranges see <!-- m --><a class="postlink" href="http://www.mi.mun.ca/users/cchaulk/eltk1100/resistor/stdvalue.htm">http://www.mi.mun.ca/users/cchaulk/eltk ... dvalue.htm</a><!-- m -->

Of course, the draw back is that the led won't operate to spec until you reach that 12V (or whatever applies to your supply), but in many cases, nowadays people use DCC, which has a constant supply to the tracks.
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#6
if you run a regular LED in parellel with a flashing LED you will have two flashing ones.
jim
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#7
jim currie Wrote:if you run a regular LED in parellel with a flashing LED you will have two flashing ones.
jim

Just curious, Jim, will they flash together or alternate?
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#8
Quote:Just curious, Jim, will they flash together or alternate?

if they are similar to the ones that I used years ago (at the time I got them from DSE here in Australia)

with a series resistor and both LEDS in parallel the flashing one would flash on and off brightly
the `normal' led would flash off and on at the same time (ie the flashing led would be on, the normal one would be off)
BUT

the normal one would be more `bright/dull/bright/dull' rather than on/off/on/off
so you would have the flashing led going on and off, while the normal led would be dull and bright rather than off and on

this was with the flashing leds from dse about 10 years ago or so mind you, so results from newer ones may be different
poopsie chicken tush
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#9
If you want to alternate flashing lights (as in a crossing signal) there is a relatively easy circuit you can build using a 555 IC, and a few other components. The cost of the parts will be less than 5 bucks.

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#10
the good old 555

it should be less than 2 bucks actually- there was a rather good online `howto' i saw ages ago that had a `birdsnest' layout that anyone who could solder (just) could do
I must see if I can find it again- was good for electronics `newbies'
poopsie chicken tush
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#11
Russ Bellinis Wrote:
jim currie Wrote:if you run a regular LED in parellel with a flashing LED you will have two flashing ones.
jim

Just curious, Jim, will they flash together or alternate?


Russ
alrenate but i'v only used it with a 2mm yellow fasher triggering a 2mm red regualr led for a cross road, as noted by others some will only dim , and you must run them with a resistor to get effect.
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#12
nachoman Wrote:If you want to alternate flashing lights (as in a crossing signal) there is a relatively easy circuit you can build using a 555 IC, and a few other components. The cost of the parts will be less than 5 bucks.

<!-- m --><a class="postlink" href="http://wild-bohemian.com/electronics/flasher.html">http://wild-bohemian.com/electronics/flasher.html</a><!-- m -->


Kevin
i use a two transistor flasher unit i found years back, the 555 is ok too but if you check that unpopular site (ebay) you can get them for .12 cents each if you buy a lot of 100
jim
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#13
<!-- m --><a class="postlink" href="http://www.techlib.com/electronics/flipflopflash.htm">http://www.techlib.com/electronics/flipflopflash.htm</a><!-- m --> - the very top/first circuit is the two transister circuit thats been used for years to make 2 alternately flashing LED lights (similar to what our level crossing lights here do, flash left/right/left/right)

a good site for a how to on the 555 timer to do the same job( has the advantage of being able to handle much higher currents so that you can have multipule flashing level crossing lights, all syncronised (most level crossings here have a 2 lamp stand either side of the road on both sides ie 4 LEDS required to be lit at a time of 8 total)

<!-- m --><a class="postlink" href="http://www.eleinmec.com/article.asp?1">http://www.eleinmec.com/article.asp?1</a><!-- m -->
<!-- m --><a class="postlink" href="http://www.eleinmec.com/article.asp?3">http://www.eleinmec.com/article.asp?3</a><!-- m -->
poopsie chicken tush
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