History
Sumida Crossing at Five
17 August 2014 23:04
Five years? It’s really been five years since I started this layout? My how time has flown. But it has: five years ago this month the layout was just a pile of boards and 2x4 plywood panels leaning against my workbench, awaiting cutting and assembly.
I’d become interested in Japanese trains a couple of years previously, and had been playing with a few of them on my Kitchen Table with a loop of Kato Unitrack. My first two trains were a Yamanote Line E231-500 (six car basic set) and the original Narita Express (253 Series, also six cars). By the spring of 2009 I had a half-dozen trains and I was thinking that it was time to retire the old HO layout, which had been collecting dust for a number of years, and build something in its place. Planning began, and by late July I was taking the old layout apart.
Then one weekend in late August, I decided that my plans were solid enough to take saw to plywood. An afternoon at the local home supply store and I was equipped with the lumber I needed to start making my 2x4 “tables”. They went together even faster than expected, eight of them in a bit more than a week, and soon I had them spread out over the basement floor on sheets of plastic, being painted with gray latex primer.
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I’d become interested in Japanese trains a couple of years previously, and had been playing with a few of them on my Kitchen Table with a loop of Kato Unitrack. My first two trains were a Yamanote Line E231-500 (six car basic set) and the original Narita Express (253 Series, also six cars). By the spring of 2009 I had a half-dozen trains and I was thinking that it was time to retire the old HO layout, which had been collecting dust for a number of years, and build something in its place. Planning began, and by late July I was taking the old layout apart.
Then one weekend in late August, I decided that my plans were solid enough to take saw to plywood. An afternoon at the local home supply store and I was equipped with the lumber I needed to start making my 2x4 “tables”. They went together even faster than expected, eight of them in a bit more than a week, and soon I had them spread out over the basement floor on sheets of plastic, being painted with gray latex primer.
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A Short History of Transistor Throttles
02 February 2014 01:41
My interest in the design of transistor-based DC throttles (aka Power Packs) for model railroading ended up causing me to pick up the DVD set of Model Railroader back issues (henceforth identified as MR). While US$200 seems like a lot, I think it was well worth it, if only to satisfy my curiosity. And it works out to less than US$0.30 per issue, so in a sense it’s a bargain. I also dug up a copy of Peter Thorne’s 1974 book Practical Electronic Projects for Model Railroaders (mine is the third edition of 1975), which has a number of throttle circuits, including one using an SCR. This book can go for rather high prices online, but I found mine at a train show last week for the cover price of US$3.50; quite the bargain.
Early-on electric model trains were run with car batteries (some early ones used AC motors with AC from a transformer instead), first apparently at 6 volts but by the 1930’s DC motors were apparently designed for 12 volts even before cars switched to the larger batteries, requiring two batteries placed in series (per MR August 1934 article on the use of DC power). DC at 12 volts was more than enough to run small motors, and early throttles were little more than a variable resistor (rheostat) to reduce voltage for slower speeds, and a Dual-Pole, Dual-Throw (DPDT) switch to reverse polarity for direction control. Often a “knife” switch would be used for the reverser, which could be left in a central “off” position to disconnect the throttle from the track.
But modelers weren’t very satisfied with these. DC didn’t allow for smooth low-speed operation, and “jackrabbit” starts with a minimum speed over 10 or even 20 scale miles per hour (16 - 32 kph) made for poor switching operations. Plus, modelers wanted to model the behavior of real trains, with simulated momentum and realistic braking action.
This led to designs for more sophisticated “throttles” and ever more complex designs as electronics technology improved. Some of the results did a fairly good job of replicating the real behavior of trains, right down to simulating the performance of air-brake systems similar to the one in the diagram at the top of this post. It’s possible some of this took place before the transistor was introduced; vacuum tubes could have been used for similar things. However, nobody appears to have published their experiences with these, so it seem likely that little or nothing was done until the transistor came along.
The development of the low-cost transistor in the late 1950’s made more complex throttles accessible to a hobbyist with a relatively minor amount of electronics skill and for a reasonable price, and the next decade was a time of rapid change, with evolution continuing into the 1970’s. By 1980, interests had shifted towards running multiple trains using command control systems (the precursors of DCC), although the roots of those went back further. And even in 1980 you could still buy rheostat throttles, although they were definitely behind the times by then. None of these technologies fully displaced the others. The transistor has in fact soldiered on into the era of digital controls, and you can still buy transistor throttles today that aren’t too different in principle from those designs of a half-century ago.
Read More...
Early-on electric model trains were run with car batteries (some early ones used AC motors with AC from a transformer instead), first apparently at 6 volts but by the 1930’s DC motors were apparently designed for 12 volts even before cars switched to the larger batteries, requiring two batteries placed in series (per MR August 1934 article on the use of DC power). DC at 12 volts was more than enough to run small motors, and early throttles were little more than a variable resistor (rheostat) to reduce voltage for slower speeds, and a Dual-Pole, Dual-Throw (DPDT) switch to reverse polarity for direction control. Often a “knife” switch would be used for the reverser, which could be left in a central “off” position to disconnect the throttle from the track.
But modelers weren’t very satisfied with these. DC didn’t allow for smooth low-speed operation, and “jackrabbit” starts with a minimum speed over 10 or even 20 scale miles per hour (16 - 32 kph) made for poor switching operations. Plus, modelers wanted to model the behavior of real trains, with simulated momentum and realistic braking action.
This led to designs for more sophisticated “throttles” and ever more complex designs as electronics technology improved. Some of the results did a fairly good job of replicating the real behavior of trains, right down to simulating the performance of air-brake systems similar to the one in the diagram at the top of this post. It’s possible some of this took place before the transistor was introduced; vacuum tubes could have been used for similar things. However, nobody appears to have published their experiences with these, so it seem likely that little or nothing was done until the transistor came along.
The development of the low-cost transistor in the late 1950’s made more complex throttles accessible to a hobbyist with a relatively minor amount of electronics skill and for a reasonable price, and the next decade was a time of rapid change, with evolution continuing into the 1970’s. By 1980, interests had shifted towards running multiple trains using command control systems (the precursors of DCC), although the roots of those went back further. And even in 1980 you could still buy rheostat throttles, although they were definitely behind the times by then. None of these technologies fully displaced the others. The transistor has in fact soldiered on into the era of digital controls, and you can still buy transistor throttles today that aren’t too different in principle from those designs of a half-century ago.
Read More...
