Flashing Red Light Circuit Diagram

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.

Flash,

I do not have the capability to take a video and post it. I will say that the flashing rate of the this circuit is the best I have seen.

Fast, slow, about how many flashes a second, or how many seconds a flash?  Does it have a 50-50 duty cycle on-off?

With 13.7 VAC on the circuit, the LED flashed uniformly 98 times per minute.

I found a flashing red 8mm LED with a frequency of approximately 2 Hz @ 12V, 56ma forward current, and 0.5V back voltage so I put this in the circuit diagram. I still need help with the diodes. I will measure the resistor and plug the value into the diagram.

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.