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Platy787

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Posts posted by Platy787

    Anyone able to identify this connector?

    in Electrics (non-DCC)

    Controller failure - low voltage

    in Electrics (non-DCC)

    Posted

    I have a couple of  the Roger Amos books. I hope the following is helpful.

     

    This is the Roger Amos High-performance closed-loop controller from Complete Book of Model Railway Electronics 2nd Edition. Quoting from the text "Transistor T1 is used as a comparator - it compares the output voltage (on its emitter) with the control voltage (on its base)."

    Further on, from the "Performance" paragraph,  because the combination of the BC107 and the TIP147 has a very high gain -

    "Consequently the speed regulation is excellent, extraordinarily so for a closed-loop controller"

     

    Many other simple controllers don't have the intermediate stage BC107 or the connection from output to its emitter.

     

    Nothing is mentioned about falling through 0v, but the diode from BC107 emitter to 0v is mentioned as being required so that the B-E junction of BC107 is protected against inductive overshoot. The omission of the diode making it difficult to stop some types of locomotives.

     

    I've made this one (High-performance closed-loop controller), another that voltage divides the feedback (Project 7: Sensitive closed-loop controller), and a centre off version (Project 8: Bi-directional controller - this one doesn't work for some locos).

    Roger Amos PWAyMan DC controller

    in Electrics (non-DCC)

    Posted

    Here's an update for anyone still contemplating making one of these controllers. I've been using the Roger Amos PWayMan DC controller for a while now, and I have to revise my comments  about it. I have an N gauge layout where each section is powered through a centre off DPDT switch that allows me to select either of 2 connected controllers. The PWayMan controller has ended up being connected as one of these controllers, with the Cooler Crawler the other. The PWayMan has quite a controllable low speed range, with the ability to set from tickover to a nice crawl speed. Using a 5 pole Poole manufactured Graham Farish loco, it starts with a growl and gently builds speed over about the first 50% of speed pot movement, with it going faster after that. I use an 18V AC plug pack with a 12V/18W lamp in series with the input for overload protection. There is the option of a pure DC output that doesn't use the PWM, via a switch.

     

    I've made more than a dozen DIY DC controllers and for me, the PWayMan is one of the best, although some may not like the amount of movement of the speed control required to get it up to speed.

    • Like 1
    • Informative/Useful 1

    Roger Amos PWAyMan DC controller

    in Electrics (non-DCC)

    Posted · Edited by Platy787
    Renamed to Pulse and DC

    Straight forward build with seemingly too many transistors. I built on Vero board and haven't put it in a case or given it a reversing switch yet. No meter for the speedo, just a no frills build. Tested with a OO Dapol LT 57XX and adjusted to give smooth start and running. The PWM/DC switch gives a slight change, but I only tested it on 2meters of straight track. Similarly with my N gauge test, it can be adjusted for smooth start and running.

     

    I have an N gauge terminus with a roundy, roundy extension and shunting performance is most important to me. I already have a number of great controllers that work very well at low speed (including the Roger Amos centre off, Wireless World and Cooler Crawler) so I probably won't put this one in a case.

     

    If anyone wants an alternative Pulse and DC combo controller, that also works well, there is a circuit available from the NGF.

    Roger Amos PWAyMan DC controller

    in Electrics (non-DCC)

    Posted

    If anyone has built this or is intending to (like me) you should be aware that there are differences in the circuits published in ETI February 1986 and Model Railway Electronics 2nd Edition (the book is later published than the magazine article).

     

    IC1 7818 / 7815

    IC3 2N6050/TIP147

    R11 390R/390K

    R14 and R13 names are swapped

    R13 1k/10k

    R14 10k/1k

     

    The regulator and darlington are probably due to component availability.

    R11 is probably wrong in the ETI article (390R) because the op amp gain in the article is given as 4.9. Was there ever an Errata published?

    I'm not sure about the R13, R14 change.

     

    I will build to the schematic in the book, but with a BD682 darlington.

    A curious short

    in Electrics (non-DCC)

    Posted

    13 hours ago, RobinofLoxley said:

     I introduced the feeds on the second board one by one and found a single straight piece of track, isolated from everything else by IRJ's, that caused the short to appear. I say short, the Guagemaster D100 power indicator remains red when the power dial is turned up, either direction, which I take to be a short.

    I have a Gaugemaster Combi (which may operate differently to your D100) which has a red led as Track indicator. It increases in brightness from off to bright as the control is moved from 0 to 100. It comes on at about 10 on the dial when it is not connected to anything. When I short circuit the output of the controller the red led still comes on, but at 20 rather than 10.

     

    In a Combi the Track indicator is not directly across the output terminals, so it will still glow, at a higher dial setting than normal, even when there is a short circuit on the output, but the Track indicator is not an indicator of a short circuit.

     

    If you put a 12V 18W or 12V 10W automotive globe in series with one of the ac supply lines, or one of the track feeds, you will get a very obvious indication (and current limit) of any short circuit.

     

    Mark

    Are Gaugemaster DC controllers PWM?

    in Electrics (non-DCC)

    Posted

    I have a Combi and it is a simple full wave controller with no active feedback. For such a simple controller it works well, although for some mechanisms it may have a large "dead band". That is, you have to turn the knob up to 30 or 40 before anything moves.

    I have recently built 12 DIY DC controllers of various designs and "tested" them to see how my N gauge motors respond. These are a 5pole (Graham Farish GP tank) , a Dapol 45XX and a Kato tram with coreless motor. The Dapol and particularly the coreless motor were unhappy with any PWM controller, although most of these had feedback. Slow speed, smooth, jerk free performance was most important for me, so the "Cooler Crawler" design was my best because it worked nicely with all my 3 motor types

     

    Anyway, have a look at the 852B Varipulse. It is available built, kit or buy parts and make it all yourself (I did this on vero board).

    http://www3.sympatico.ca/kstapleton3/851.HTM

     

    I've think I've seen another recommendation for the 852B on this forum.

     

    Cheers,

    Mark

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