Jump to content


  • Content Count

  • Joined

  • Last visited

Community Reputation

23 Neutral

Profile Information

  • Location
    Helsinki, Finland
  1. From the wikipedia (about standard 4 mm banana plug): https://en.wikipedia.org/wiki/Banana_connector#History "-- The pin's diameter is nominally 4 millimetres (3⁄16 in). The pin has one or more lengthwise springs that bulge outwards slightly, giving the appearance of a banana [bunch]. --" pekka
  2. 2.6 mm banana plugs or 'Marklin' plugs. E.g. here: https://www.conrad.com/search?search=2.6%20mm%20jack%20plugs&searchType=regular (I'm sure a UK suppliers also exits) pekka
  3. This is not strictly simple, needs common anode signal heads, but the component count is still rather small, and there are no processors or fancy digital buses, just one IC (quad operational amplifier) for four LED lamps. Cut the wire leading from (grounding) switch to the LED's curent limiting resistor and connect the circuit points (A) and (B) in between: I drew this in 2006 and had it at Tapiola Parish Model Railway Club's web site's page https://taprk.org/eng/project/semaphore/ for 14 years. After showing this at MERG BBS i was noted that the schematic had power pins of the OpAmp reversed , This is the fixed one! The idea is that when swiching on a LED, first nothing happens, and then, after about half a second the LED starts to brighten, and is fully lit at one second after being switched on. When switched off, the LED becomes dark within half a second. So, if one switches off one LED and switches on another, the first one will go dark before the second one will start to brghten up, thus giving the illusion of "changing aspect through dark". I wonder if this is the desired action... True, may be done with much less components using a processor following x^3 curve... pekka
  4. A link -- please ? pekka
  5. John, you are preytty good with this – aren't you Excellent! Looking at this now, the system has departed from the NX into something different but rather elegant! If I should do this for myself I'd rather have the toggle switch between buttons A and B to select the "end". I do hope the original writer – Spikey – has enjoyed this as much as I have! pekka
  6. Hmm... I don't think so.... I know I should have marked the coils to follow the track letters, but being lazy I left the coil letters as they were: coil "a" leads to track "B" and coil "b" leads to track "A". Sorry! I know now that I should not have done it the way I did. If I may borrow the words of Spike Milligan: "It's all rather confusing, really!" Suzie: Yes — but I would so much hate to add buttons in between and ruin the NX idea pekka
  7. John ks — thanks for the addition of the missing diode! I did have a strong feeling that I missed something Are you quite sure about the swapping of the point motor V3a/b? I have my suspicions... Replacing buttons A and B with a toggle switch is a good addition, especially if buttons A-B and buttons 1-4 are far apart and the hand span is not long enough and the walkaround loco controller or tea mug is in the other hand... With Siemens mosaic panels I've seen the mosaic cover removal magnet being parked over a turnout group button to allow turnouts be thrown with one hand. I had a dream of adding flank protection to the plan (i.e. tying coils V2+ and V3a somehow together), but run into difficulties. I trust it could be done with point motors having no common lead, like Peco, but i just cannot get it right. One should always have equal amount of diodes for each simultaneously turning coils, else the one with less diodes will get most of the juice from the CDU. Again — thanks for the correction pekka [PS: is it customary here at RMweb to a) replace (or try to replace) incorrect schematic on previous message with a corrected one, or b) add a new schematic to later message, or c) leave it as it is?] / PSi
  8. Would pressing two buttons -- like in NX system simultaneously be an acceptable solution? Double slip may mentally be "broken up" into two ordinary switch, like below: I'm using nomenclature used in Finland (and probably in Germany) to denote different ends of a double slip. The letters within coils of twin-coil motors will cause route to enter or exit at the track end with the same letter. As one splits the double slip into to two ordinary switches, the coils "mentally" look like shown above. Should you know this beforehand, then I apologise. As you mentioned that you already used a three way centre-off switch for the spur you would have connected the switch to the point motor denoted with letters a and b. The other motor you would connect to your diode matrix as an ordinary turnout. Now, if the pressing of two buttons atthe time is ok with you, then you could do something like what is shown below. It has in a way two diode matrixes, one at the "plus" side of the turnout motors and another at the "minus" side of the point motors: Note that the point motor V3 a/b is "upside down". By pressing button A or B at the same time as pressing button 1...4 will set the route between those buttons. Turnout V2 is thrown to direct route when the turnout V1 is set to diverging route. This is only to consume some energy from the capacitor discharge unit to prevent point blades of turnout V1 becoming loose from the throw bars, as suggested by DavidCBroad (I too have done that mistake myself at Tapiola club, see photos at https://taprk.org/eng/show/prp_2002/ ) Now there will be at minimum 2 and at maximum 4 motors operating at one time. Due to having diodes at the "plus" and "minus" side they will tax more compared to single sided diode matrix. If you can invest to another capacitor discharge unit, you could then feed button A with one CDU and the button B with another and have the minus sides tied together (make sure this is ok from the manual of the CDU of your choosing). This way the CDU for button A will fire 2 or 3 motors at one time and the CDU for button B will always fire two motors at one the time. I have not double checked the diagram, so beware of typos... Ah, and always use protection diodes or snubber diodes across the motor coils -- and beware of the polarity of point motor V3 a/b. pekka
  9. One resistor case: what if the connection to frog is interrupted (wire loose, or point motor's internal switch develops a fault or the switch is just too slow): then the LEDs will be in series across the supply with no resistors! I too would put two wire bi-colour LEDs (those, that have two leads and which will have red or green LED inside the LED case on. depending on polarity, and yellow if fed with AC, like DCC), and two resistors into the schematic. It appears that many consider reverse voltages in excess of LED manufacturers datasheet's advice safe enough, as LED will operate like a Zener, and -- provided the reverse current is low enough when the reverse break down voltage is passed there is no eminent damage. If all LED manufacturers warn aginst reverse voltages, I belive one should not encourage or advice dismissing the warnings given by manufacturers, especially when the advice is given to a person apparently not yet quite familiar with the LEDs. I feel one should suggest to follow rules, and only cut corners when, due to experience, one is confident that one is knowing what one is doing, and one can estimate the risks. A document evaluating the suitability of common automobile usage of LEDs in aircrafts is rather interesting (the PDF will automatically load) from: https://docs.broadcom.com/docs/5980-1504E After reading this I went and crossed over my suggestion of using slow 1N4001 diode as forward protecting diode at at another thread here due to slow speed. Just recalling: I have made a DIY DCC decoder (based on Probst decoder https://taprk.org/eng/project/dcc/diary.html ) once that had the rectifier built from 1N400X type diodes that I happened to have laying around the desk. The diodes got quite warm with no load, as they were so slow to switch off at polarity change, and the bridge rectifier was shorting the track power for a short moment at each DCC polarity change. I should have learned from my mistakes... pekka
  10. I think Sharris has the right answer: one resistor for each LED. True, you can manage with one resistor per head, but you cannot adjust the relative brightness of each LED that way. I think it would be a good plan to find out the correct (or suitable) resistor values like sharris suggests for each colour of a LED and this way match the brightness of the LEDs, and then (with power switched off) measure the common resistance over the combined 1k fixed and adujustable resistor for each LED colour, and use those values when purchasing the resistors for each colour of LEDs. Resistors are cheap. I would also suggest taking the common wire of each signal mast or gantry through a rectifying diode. Any cheap small rectifying diode will do, like 1N4148 or 1N4001 or similar. Why? The diode would protect the LEDs aginst accidental polarity swap, as the LEDs will not generally tolerate reverse voltages in excess of 5 volts or so. If the supply voltage is accidentally reversed, the series resistors will not reduce the voltage seen by the LED, as no current will initially flow, thus the resistor will not create voltage drop. I'd put the resistors and the diode close to signal masts (gantries), right to the ends of the thin drop wires and cover the soldered joints with heat shrink tubing like sharris suggests. When the signal mast or gantry is removed for repair, painting or whatnot the resistors and the diode will come out with the signal mast (or gantry), and when checking the signal mast at the desk one will not accidentally apply full voltage directly to the LED. If one is fiddling with the wiring within the control panel or cables and connectors between the layout and panel, the accidental shorts or power reversals would not distroy the LEDs as the resistors and the diode are near the LEDs they are to protect. I have once in my youth exploded a (then rather expensive) LED due to applying reverse 9 volts from a battery directly across LED terminals -- good thing I had my glasses on. pekka
  11. I do not recall when The Model Railway Club switched from Dexion slotted bolted frame to Dexion Speedframe. If my memory serves right the slotted bolted stuff went to Gauge One "group" who assembled their live steam layout subframe from bits and bobs at every exhibition. During one exhibition I took part in one of the "Speedframe gang" that assembled the barriers before the show was opened and knocked them down when the show ended. Each group had a special trolley with compartments for different corner pieces, tubes and spare plastic inserts. A computer drawn "ascii art" plans needed to be followed to the letter (!?!) while assembling the Speedframe barriers. Plastic mallet was the only tool needed. Quick and efficient. pekka
  12. Photographs - yes - alas no links to good ones, I'm afraid. These were taken on my first ever visit to National Model Railway Exhibition at Central hall Westminster. The year was 1978, pekka
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.