04-12-2009, 08:24 PM
Way back in the day, I completed a N&W CF caboose project (AMB model) that I had decided to put lighting in. Wouldn’t it be cool, I wondered in my outside voice, if I installed a function only DCC decoder so that I could control two individual lights in the caboose, turning them on as the brakeman or conductor boarded the caboose (in my imagination) and lit first one kerosene lamp, then wandered to the other end and lit the other? I certainly thought so!
(you can find the gory details of the complete build here:
<!-- m --><a class="postlink" href="http://www.zealot.com/forum/showthread.php?t=155662">http://www.zealot.com/forum/showthread.php?t=155662</a><!-- m -->)
The end result looked something (well, exactly) like this:
![[Image: p76722903-3.jpg]](http://goodman312.zenfolio.com/img/v1/p76722903-3.jpg)
There was one problem (and this is where the good Dr. “Lights? I don’t need lights – they just complicate things” Wayne starts snickering…). FLICKERING! Not every now and then; the “off” side of the flicker was mostly every “now”.
So when I started this,
![[Image: p437450373-3.jpg]](http://goodman312.zenfolio.com/img/v7/p437450373-3.jpg)
I figured I’d address the issue. Being just knowledgeable enough about about electronics to cause myself problems, I decided the answer was CAPACITANCE. Something that would keep the lamps a-glowing across whatever issue was causing the flicker. Sound decoders use this to keep the sound alive if a current interruption is encountered. I figured the same idea would work for lights so I built this:
![[Image: p140372577-3.jpg]](http://goodman312.zenfolio.com/img/v7/p140372577-3.jpg)
(BTW, I take no credit for the design. This exact circuit was designed by a gentleman on a yahoo DCC mailing list I’m on)
On board this mule is the TCS FL4 function decoder, with a 25 volt 470 microfarad capacitor, a 1/2 watt 100 ohm resistor and 1N4002 diode (the last two in parallel) between the striped negative lead and the blue common wire. The idea being that the capacitor would store a charge that could be dumped to the circuit when it went dead, with the diode controlling which way the current went, and the resistor slowing down the initial charge of the capacitor so that the system didn't see the sudden rush of current as a short. (this gives me a headache every time I think about it, so give me a few moments…). Ok, better. Importantly for later, the trucks were those from the caboose pictured above - I’m a tester – I needed at least one control.
With much anticipation, I put this sucker on the track and was elated to find that the flickering was… Wait… Still there? So I put ANOTHER capacitor in parallel with the first – the flicker was smoother, but the lights still flickered. Doh.
Time for the project to switch from a proof of concept /level of capacitance test for the new twins to trouble shooting a problem that wasn’t what I thought it was. Hmm.
More later!
(you can find the gory details of the complete build here:
<!-- m --><a class="postlink" href="http://www.zealot.com/forum/showthread.php?t=155662">http://www.zealot.com/forum/showthread.php?t=155662</a><!-- m -->)
The end result looked something (well, exactly) like this:
There was one problem (and this is where the good Dr. “Lights? I don’t need lights – they just complicate things” Wayne starts snickering…). FLICKERING! Not every now and then; the “off” side of the flicker was mostly every “now”.
So when I started this,
I figured I’d address the issue. Being just knowledgeable enough about about electronics to cause myself problems, I decided the answer was CAPACITANCE. Something that would keep the lamps a-glowing across whatever issue was causing the flicker. Sound decoders use this to keep the sound alive if a current interruption is encountered. I figured the same idea would work for lights so I built this:
(BTW, I take no credit for the design. This exact circuit was designed by a gentleman on a yahoo DCC mailing list I’m on)
On board this mule is the TCS FL4 function decoder, with a 25 volt 470 microfarad capacitor, a 1/2 watt 100 ohm resistor and 1N4002 diode (the last two in parallel) between the striped negative lead and the blue common wire. The idea being that the capacitor would store a charge that could be dumped to the circuit when it went dead, with the diode controlling which way the current went, and the resistor slowing down the initial charge of the capacitor so that the system didn't see the sudden rush of current as a short. (this gives me a headache every time I think about it, so give me a few moments…). Ok, better. Importantly for later, the trucks were those from the caboose pictured above - I’m a tester – I needed at least one control.
With much anticipation, I put this sucker on the track and was elated to find that the flickering was… Wait… Still there? So I put ANOTHER capacitor in parallel with the first – the flicker was smoother, but the lights still flickered. Doh.
Time for the project to switch from a proof of concept /level of capacitance test for the new twins to trouble shooting a problem that wasn’t what I thought it was. Hmm.
More later!
Matt Goodman
Columbus, Ohio
Columbus, Ohio