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As you may have read on the 3-Rail Forum, the Cedar Rapids Skytop Lounge Car of my Olympian Hiawatha took a dive last week, so I have it all apart for repairs. I found the leads to the red flashing LED uninsulated and almost in contact with the metal base of the car. One thing leads to another, so I studied the LED flashing circuit, and here's a diagram I made by interpreting the PCB.

 

 

The flashing rate of 1.6 Hz (98 per minute) is really nice on the Cedar Rapids, so I want to make use of this circuit for other projects.

 

 

 

Flasher Circuit - Lionel Cedar Rapids

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  • Flasher Circuit - Lionel Cedar Rapids
Last edited by Bobby Ogage
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If the resistor is large, the capacitor will take a while to charge enough to light the flasher LED.  Once the LED fires, the current through the resistor will be too small to sustain the LED.  When the capacitor discharges sufficiently, the LED's flashing circuit will die until the voltage builds up again.  (This is all speculation!)

 

That would be a handy circuit.  Every flashing LED I have seen is too fast, and this would slow it down.

At 56ma, I suspect you're overdriving the LED.  Does the spec sheet really say 56ma?  I hope that's not an average current.

 

Since you're using a flashing LED, I don't see why a simple resistor, diode, and a filter cap won't do the job, I sure don't see the need for a bridge rectifier for track voltage driving an LED.  I also wonder about the small value of the cap for filtering the 120HZ ripple from the rectifiers, that seems marginal.  When the flashing LED is connected without filtering to a rectified AC, it doesn't work properly, so filtering is required.

 

For constant intensity, I'd probably toss in a three terminal regulator.  For conventional that would be a good idea, probably not necessary for command operation.

Hi John,

 

The LED spec is here: http://www.fort777.co.za/index...amp;products_id=5445

 

The resistor measures 1490 Ohms, so 1.5K is in the diagram. I was finally able to read one of the diode markings, and they are 1N4002.

 

I understand the need to rectify the track voltage, but I have no idea why Lionel chose the bridge configuration in the diagram. I guess it was a matter of low material cost where the extra labor to assemble the bridge in China is insignificant. I will use a PCB ready rectifier instead of the four 1N4002 diodes.

 

 

 

 

Hi, first of all, what is the flashing red light for? The reason I am asking is that I bought a flashing red light for the top of a radio tower from Evan's Designs LED's that can be battery operated or with track power up to 19 volts. They are only about $3.00 plus low cost shipping. I also bought their police car LED package that I put in a 1/43 1941 Ford that includes two white headlights, two red taillights and a flashing gumball for the roof. It looks and works great. I also have two fire and two welder LED lights from them. All of these are transformer powered. I sould like a commercial for these guys, don't I? Seriously, they really add to the realism of my layout and are inexpensive and easy to use. Originally Posted by Bobby Ogage:

As you may have read on the 3-Rail Forum, the Cedar Rapids Skytop Lounge Car of my Olympian Hiawatha took a dive last week, so I have it all apart for repairs. I found the leads to the red flashing LED uninsulated and almost in contact with the metal base of the car. One thing leads to another, so I studied the LED flashing circuit, and here's a diagram I made by interpreting the PCB.

 

 

The flashing rate of 1.6 Hz (98 per minute) is really nice on the Cedar Rapids, so I want to make use of this circuit for other projects.

 

 

 

Flasher Circuit - Lionel Cedar Rapids

 

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