OK guys, this has probably been run around before. Am I right in thinking that pulse injection and momentum are not smooth wave power? My Digitrax says that I can use smooth wave power packs from the jump ports. Does anyone make one? does anyone know where I can find instructions to build one? I have a terminal at the end of a branch that I have a dedicated switcher for and was thinking that this might be less expensive than a hand held throttle. I have an old Spectrum Plus that has just speed and direction, and a Bachmann tech 2 with pulse that I can turn on and off. Will either of these work?
Phil, CEO, Eastern Sierra Pacific Railroad. We know where you are going, before you do!
Haven't heard it called smooth wave. Maybe they just want a clean voltage like a filtered DC supply.
Springfield PA
Sierra ManOK guys, this has probably been run around before. Am I right in thinking that pulse injection and momentum are not smooth wave power? My Digitrax says that I can use smooth wave power packs from the jump ports. Does anyone make one? does anyone know where I can find instructions to build one? I have a terminal at the end of a branch that I have a dedicated switcher for and was thinking that this might be less expensive than a hand held throttle. I have an old Spectrum Plus that has just speed and direction, and a Bachmann tech 2 with pulse that I can turn on and off. Will either of these work?
I have never seen smooth wave DC. DC either has some plus/minus variation or is smooth, i.e. pure DC or as pure as can practically be filtered.
That is their terminology for pure DC. Not all power packs are pure DC. Usually the pure DC power packs call that out as they are more expensive than standard power packs and some modelers want pure DC.
Do a Google search for pure dc model railroad power pack. I have done that and got results.
Google is your best friend. Forums are your second best friend.
Rich
If you ever fall over in public, pick yourself up and say “sorry it’s been a while since I inhabited a body.” And just walk away.
My bad guys. The book doe's say smooth DC power. No mention of wave. Might explain why I got a lot of surfing results when I Googled smooth wave! Thanks.
I believe that what Digitrax is calling "smooth wave" is normal, rectified DC without any filtering. This has a rounded 120Hz pulse form, and is/has been standard output on low end power packs for decades. The Digitrax jump port reads the incoming voltage from the power pack and uses that to set the appropriate speed step in DCC.
A DC pulse train where the voltage is constant but the pulse duration changes to control the speed of the motor would make it more difficult for the jump port to read a change in voltage when you move the throttle.
Pulse injection and TAT and Cool Crawler and many other more sophisticated throttles (but not PWM throttles) only use pulses for low DC voltages, replacing the pulses with filtered DC as the voltage rises. These throttles may or may not work well in the jump port for low voltages, but will work just fine at mid and higher voltages. If there is a switch to turn the pulses off, then it will work throughout the range on the jump port.
Bottom line - any DC power pack without pulses, or with the ability to switch the pulses off, should work fine in the jump port. Pure pulse supplies like PWM throttles will likely not work in the Zephyr jump port.
Fred W
Join the Digitrax Yahoo group. There are several build your own jump throttles in the file section there. Simplest one will set you back a couple of dollars and maybe twenty minutes to build. It uses a 9 volt battery. Battery power is as "smooth" as you can get.
I built one of those, and it worked well. But 2 points: get a quality potentiometer from Mouser or Digi-Key, the Radio Shack ones are absolute junk - there was no control over the first 50% os the range and rather erractic control over the rest, and make the battery easily accessible or add an on/off switch in series with one of the battery leads as the battery will continuously drain unless removed or disconnected.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.