Dave Zucal posted:Has anyone ever tried replacing an existing firebox glow bulb with a flickering LED? I've been tempted to do this on my MTH steamers that just glow. My concerns though are it may cause all the rest of the bulbs on the engine to be unstable in their lighting and I believe the PS-2 voltage to the firebox is only 1.5 volts which may be too low for a flickering LED. Is it do-able?
As GRJ says the flickering LEDs you get on eBay for a couple of pennies each require a stable DC voltage. That's because there is an electronic circuit built-in to the LED that generates "random" pulses to drive the LED and hence create the flickering effect.
You need a handful of components to regulate the PS2 chopped lamp voltage into a stable DC voltage. It's not that such a circuit is expensive ($1-2 in parts) but requires soldering, wiring tiny components, installation into a typically cramped space. To wit, GRJ's tiny board also uses a voltage regulator to provide stable DC to the flickering LEDs!
As a historical note, the first "generation" of tealights from places like Dollar Tree had a circuit board with a small IC chip (the black blob on the circuit board) that generated the flickering pulses to drive a regular (non-flickering) LED. Then "they" figured out how to integrate the flickering circuit right into the LED itself as shown above. Now these tealights are just a 3V coin battery, an on-off switch, and the flickering LED.
