QUOTE: Originally posted by MP173 One of my favorite memories and I took a slide years ago of it was during a blinding snowstorm how a GTW searchlight signal pierced thru the snow with it's red light. Shine on! Probably my favorite is color position signals and then have a dwarf signal at the end of a siding. Good stuff!
QUOTE: Originally posted by chad thomas I too am interested in signaling. On my last layout I built my own signal system (a small one) and your right, for the most part it is simple logic. I used 555/567 phase lock loops for track detection (powered locos only). On the simple blocks I used 7400 series logic gates. If I remember right 1 NOR gate and 1 NAND gate for each direction with Ultra bright LEDs in an enclosed box each pointed at the end of a plastic fiber optic line that ran to the signal head. This was duplicated for the other direction. For blocks that had more complex arrangements I used EPROMS (electronic programable read only memory) and each address line was assosiated with a track condition (through buffer or inverter gates) usually 4 for each track for occupancy of the blocks ahead, one for switch condition and one for holding (emulating CTC) at the absolute signals. With 8 data pins for outputs I could run 6 LEDs, 2 of each red/yellow/green for a two head signal with 2 lines to spare. I cplanned on using those two extra lines to drive 555 timers to get flashing aspects, but I never did that. I had to buy a PROM blaster and write the truth tables to use the EPROMS. It took a lot of time and effort to build the system (mostley building the signals themselves, which I still have). The problem with that set-up was the track only had about 60 linear feet. So there was not enough blocks for it to serve a purpose. Right about the time I worked the bugs out I had to move and that layout met mr. sledghammer. That was over 10 years ago and I've only had one layout sience and that was even smaller. I had planned for years to use this same system on a future (and bigger) layout but after a visit to the La Mesa Tehachappi layout and seeing there pc controlled signal system that can be run as ASB or CTC, I think that is the route I will go. And I can still use all those LED / fiber optic signals I built.
Brian (IA) http://blhanel.rrpicturearchives.net.
QUOTE: Originally posted by chad thomas .....a visit to the La Mesa Tehachappi layout and seeing there pc controlled signal system that can be run as ASB or CTC.
Deshler Ohio-crossroads of the B&O Matt eats your fries.YUM! Clinton st viaduct undefeated against too tall trucks!!!(voted to be called the "Clinton St. can opener").
QUOTE: Originally posted by MP173 Chad: Maybe you misunderstood me. On each side of the track there is a brown rail like object. Are those new tracks to be installed? Great shot...btw ed
QUOTE: Originally posted by Tulyar15 Those of you interested in signalling might like to look at this site:- http://www.signalbox.org/ It deals mostly with British pattern signalling but does have links to sites concerned with signalling in other countries.
QUOTE: Originally posted by CrazyDiamond At the risk of getting many differing answers again I have to ask: Train #2 is following train #1, but is slowly catching up. It has gotter the clear signals all the way so far. However it is now approaching the block that does not have a "full clear"....so what will the signal aspect be?
QUOTE: Originally posted by chad thomas Brian, The 555 is a very versatile multivibrator that can be used for many timing or signal generating tasks. In my signal system I use it for two things. One is for the flashing signals, the 555 is timed for a little over one second in frequency with roughly a 50% duty cycle to match what the timeing of signal flashing is. The other use is in the track detection. The 555 is used to generate a high frequency signal. That signal is applied to one rail through a coupleing capacitor (That blocks track voltage). When a locomotive is in the block that high freq signal is coupled to the other rail. Attached through another coupleing capacitor is a 567 phase lock loop chip. This 567 PLL chip has a pin (lock) that when it senses the high frequency on the 2nd rail will provide a "high" logic state. This "high" logic state is what tells the rest of the signal logic that the block is occupied. I had to add small capacitors to all the wheelsets (locos and EOT equiped cars) to shunt the high freq signal between the rails. I can't remember what frequency I used but I'm sure it was around 1200hz.
QUOTE: Originally posted by blhanel QUOTE: Originally posted by chad thomas Brian, The 555 is a very versatile multivibrator that can be used for many timing or signal generating tasks. In my signal system I use it for two things. One is for the flashing signals, the 555 is timed for a little over one second in frequency with roughly a 50% duty cycle to match what the timeing of signal flashing is. The other use is in the track detection. The 555 is used to generate a high frequency signal. That signal is applied to one rail through a coupleing capacitor (That blocks track voltage). When a locomotive is in the block that high freq signal is coupled to the other rail. Attached through another coupleing capacitor is a 567 phase lock loop chip. This 567 PLL chip has a pin (lock) that when it senses the high frequency on the 2nd rail will provide a "high" logic state. This "high" logic state is what tells the rest of the signal logic that the block is occupied. I had to add small capacitors to all the wheelsets (locos and EOT equiped cars) to shunt the high freq signal between the rails. I can't remember what frequency I used but I'm sure it was around 1200hz. OK, I gotcha now! Any idea on the R and C values?
QUOTE: Originally posted by chad thomas QUOTE: Originally posted by CrazyDiamond At the risk of getting many differing answers again I have to ask: Train #2 is following train #1, but is slowly catching up. It has gotter the clear signals all the way so far. However it is now approaching the block that does not have a "full clear"....so what will the signal aspect be? Depends on how many aspects the signal system can show, in areas where there is only 3 aspects (red,yellow,green) #2 would see yellow first. If the system has 5 aspects (red,flashing red,yellow,flashing yellow,green) then #2 would see flashing yellow first.
QUOTE: Originally posted by CrazyDiamond Thanks Chad, I thought there were two reds behind a train?? G............G.............G.......<<<TRAIN<<<.......R...........R.............Y.............FY............G ############################################################################## Or is that on other RR like UK, subways, etc? ...and not in North America?
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