flashing LED's

[pcdocde]

I would like to add animated crash scenes to my slot car racing layout. How can I add flashing LED's to some 1/32 scale emergency type vehicles,fire,police,tow truck,etc ? Would like for them to operate off of a AC adapter instead of batteries. Thaks in advance !

[k7elp60]

The simple way would be to use a blinking LED. Radio Shack p/n 276-036 is a red one. As with all LED's you need a current limit resistor. Give is more info as to the Wall transformer you plan to use and how many LED's you want to use. With the LED mentioned a 6V DC wall transformer and a 150 ohm resistor would be fine.

[pcdocde]

I have a couple of WALL transformers I could use ,4.5,6, or 12 volt. Probably about 8 LED's. Would they have to be connected in series or parallel ? Thank you

[Bob Scott]

What are the current (mA) ratings of each transformer? Are they all DC output?
Each plain LED should need ~5mA DC as indicators; more if you want them brighter up to their max rating. Check the specifications on their data sheets.

Bob

[k7elp60]

It has been my experience that if you connect regular LED's in series with flashing LED's all the LED's in that string flash at the same rate as the flashing LED. If you wanted too you could put two regular LED's in series with one of the flashing LED's and then a resistor connected to the 12V DC wall transformer. Each string of LED's needs it's own resistor. On problem is that the wall transformers is that the output voltage can vary quite a bit depending upon the load on it.
Do you have any kind of a voltmeter that you can measure the voltage on the wall transformers?
If you can it will make things a lot easier. I'll try to help you either way.

[Janitor Tzap]

I think were missing a very important point here.
The Slot Cars draw their power from the track rails.

On older Slot Car setups the 12Vdc or 18Vdc was controlled by hand controllers.
That had a rheostat in it that increased, or decreased the voltage.
Making the car go faster, or slower.

A LED circuit wouldn't come on until the voltage was high enough.
Plus, you would need to regulate the voltage going to the LED circuit.
Otherwise you could cause the LED's to burn out when you put the full 12Vdc,
or 18Vdc across the power rails.

I haven't played with the newer Slot Car setups.
But, I think they have gone to a digital control setup,
like many of the Train sets that are out now.

If that is the case here...
Then there shouldn't be a problem tapping off of the rail pickup brushes in the car,
and sending the power to the LED circuit.
{But you'll still need to regulate the voltage to the LED circuit.}
Since the DC at the track rails are normally constant (12Vdc to 18Vdc).



Signed: Janitor Tzap

[pcdocde]

The cars I will be using with the flashing led's will not be on the track or be powered by the track. They will be part of a static display along side of the track. Went to Radio Shack all they have in flashing led's are red, but they have all the other colors I need that do not flash,so what I really need is a module that will interrupt the power from the wall transformer every few seconds. I do have a VOM so I can measure the correct voltage from the wall transformer. Thanks for all the help so far,my son cannot wait to see the final results !

[MrAl]

Hi,

Have you ever worked with any ic chips like the 555 timer ic?
Have you done any other work in electronics so you might build your own circuit, or
are you willing to learn?
Can you solder?

[Bob Scott]

Here's a nice 555 tutorial with lots of examples, including some to flash LEDs:
http://www.sentex.ca/~mec1995/gadgets/555/555.html

and a whole bunch more circuits to make LEDs flash on-off, in sequence, upside down, left to right........
http://www.hobbyprojects.com/quick_circ ... atics.html

[k7elp60]

The cars I will be using with the flashing led's will not be on the track or be powered by the track. They will be part of a static display along side of the track. Went to Radio Shack all they have in flashing led's are red, but they have all the other colors I need that do not flash,so what I really need is a module that will interrupt the power from the wall transformer every few seconds. I do have a VOM so I can measure the correct voltage from the wall transformer. Thanks for all the help so far,my son cannot wait to see the final results !

I still think you can do it with flashing LED's if you want to. Like I said earlier you can put regular LED's in series with flashing LED's and the regular LED's will flash. You can even hide the red flashing LED so it's not visible, or wrap it with black electrical tape.
Please tell us which way to want to go, flashing LED's or other circuitry.

[Janitor Tzap]

The cars I will be using with the flashing led's will not be on the track or be powered by the track. They will be part of a static display along side of the track. Went to Radio Shack all they have in flashing led's are red, but they have all the other colors I need that do not flash,so what I really need is a module that will interrupt the power from the wall transformer every few seconds. I do have a VOM so I can measure the correct voltage from the wall transformer. Thanks for all the help so far,my son cannot wait to see the final results !

Sorry, I thought this would be for the cars running on the track.
Well, here are a few simple flasher circuits that you can make.
http://wild-bohemian.com/electronics/flasher.html


Signed: Janitor Tzap

[Engineer1138]

If you use the flashing LED to flash the others, an LM340 + 100 ohm resistor makes a very good 12mA current regulator for LEDs.

[dacflyer]

you can still use the flashing red led to power your other leds, just hide the red one,
if i remember right the red led can handle up to 7 volts with its internal circuitry, but still you want to measure things out..i have been able to run 1 flasher led and 3 regular ones with a 12v wal wart. try 5 leds 1st, then if its not quite bright enough then remove one.
its not that difficult, and most leds i have messed with, usually max out at 20ma.
its a down and dirty set up but it works..
if you want more complicated, you can play with a 555 times, and get alternating flashing pattern. its simple also. i could help you if needed with a schematic..but if you just want a simple flasher, just use the flashing led in series with other leds
good luck..