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Evolution of the N8101 DC Power Source
(for those who wondered)
The N8101 DC Power Source came into existence as a byproduct of our family of N80XX Simulators and we have YOU to thank for it. While the original intent for these Simulators was to provide superior lighting effects for modelers using DCC and wanting the extreme longevity and tiny physical size of LEDs, it was soon discovered that two additional areas of use were rapidly gaining popularity. Excellent customer feedback and requests for additional effects for both analog (non-DCC) model railroaders, and DCC users wanting effects not tied to locomotive decoders, resulted in the development of an inexpensive (and small-sized) way to get track power (in any form) to our Simulators. After several iterations in design, we feel this simple circuit using the industry's very latest components will meet the need.
Delusions of Grandeur
"You win some... and..." you know the rest. Originally, our plans for the N8101 were to be the magic potion, the cure-all, the grand elixir, of track power conversion and analog support. Knowing that in the analog operating world, things don't start happening until the DC voltage level gets high enough to make things work, we set out to develop a "magic" circuit that would use buck-boost regulators, dual-comparators and all sorts of other sophisticated components to make everything work while using an input voltage of only about 2 volts!
This will be the greatest thing since the Internet!! Ahhhhahahahahah!!! (picture: Dr. Frankenstein)
Well...after much (rather lengthy) discussion with various Applications Engineers at major component manufactures (Texas Instruments, National Semiconductor, Maxim, etc.) it became obvious that we would likely end up with 10 pounds of stuff in a 5-pound sack, and would need to charge you your first born for this thing. OK... so we were pushing the state-of-the-art a bit. On to plan B..., uh, plan C. To make a long story bearable, everything we did to streamline, simplify or cost-cut either dramatically raised the input voltage requirements of left the whole circuit open to self-destruction from lack of sufficient over-voltage protection. More talks, more tests, on to plan D, E, etc.. The weeks rolled by. This was not going as planned. For you Mel Brooks fans, this was definitely the brain of Abby-Normal.
A humbling experience
Just when we were ready to pick a gravesite, the gray-bird of moderate complacency flew in our window (forget the blue-bird thing). A manufacturer that we've purchased from (and subsequently got on their new-products mailing list) announced the release of a brand-new, state-of-the-art, Dual In-series pair of ultra-low Vf (forward voltage-drop) Schottky diodes, all packaged in a super-small SOT-26 surface-mount package, with... get this... interconnects to allow the diodes to be used as a... wait for it... bridge rectifier with hardly any voltage loss! WHOA!!! Fewer components and circuit traces = smaller footprint and less solder joints = shorter assembly time = lower cost!
Maybe we can pull this off after all, and make it seem like this is what we were actually planning all along... NAH, NOT. Just take your lumps and tell it like it is. Be humble.
Not long after receiving samples of the new Schottky "bridge" and doing some bench testing, we were informed of a new multi-layer capacitor developed by a major Japanese manufacturer that allowed for a much-reduced package size. Knowing that in our business, smaller is always better, we ordered some samples. Things were definitely looking up! What we received were 10μf capacitors the size of the little 1μf caps we've been using in other projects. Truly amazing, and... they performed beautifully. Even better than their much larger cousins.
Here we are
The old axiom K.I.S.S. (keep it simple, stupid) has certainly found a new home in our R&D area. While the DC Power Source we have, is certainly not the module we envisioned to begin with, this simple design using very state-of-the-art components allows for a very small footprint (much, much smaller than we originally planned on), and very low cost. It may not boost voltage, but it hardly robs any at all. The tiny, but highly efficient multi-layer capacitor does an excellent job of smoothing the rectified DCC signal, so our LEDs and Simulators perform as they should. When it's all said and done... a very decent compromise.
To those customers who have waited patiently while we worked through several false-starts, thank you for sticking with it and prodding us forward, and... thank you for allowing us to air some dirty laundry, it smells better now.
Please see the Analog support, DCC support, or AC support in the More Info table for an in-depth description of ways to use this little module.
© 2008 Ngineering