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3 aspect model RR signalling help plse

Discussion in 'Electronic Projects Design/Ideas/Reviews' started by angie1199, Nov 15, 2009.

  1. angie1199

    angie1199 New Member

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    I was going by my latest schematic (http://www.electro-tech-online.com/attachments/detector13a-jpg.36708/)

    Not going to use a relay now as the circuit is working with transistors and resistors only.
     
  2. Raiway Pete

    Raiway Pete New Member

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    Are you sure it's not 47K instead of 470K. 47K is very good. 470K may give you problems on a damp day. ¼ watt on track resistors should be OK.
     
  3. angie1199

    angie1199 New Member

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    Nope, definately 470K, Tried a 550K and it didn't work.

    Are we now saying it's too sensitive? If so how do I lower the sensitivity?

    (mutters) this is now getting silly :D (end muttering)
     
  4. dave

    Dave New Member

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  5. MrDEB

    MrDEB Active Member

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    you have t working using a transistor for the detect on the signal circuit?
    if so then hopefully all is good?
    your going to put ONE detect and one signal per pc board?
     
  6. angie1199

    angie1199 New Member

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    Yep, both signalling and detect circuits work.

    One detector and signalling per board.
     
  7. Raiway Pete

    Raiway Pete New Member

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    You won't remember this but we had "You can't tell Stork from Butter". Well in the RAF over the radio communications "We couldn't tell talk from mutter".

    :)

    You can quit muttering. Everything is just fine. You can adjust the sensitivity to your needs when everything is up and running in the envionment you have. Right now all is positive. If you have rising damp and the moisture is salty then your railroad is in the wrong room. Be aware that when you put down the track gravel the glue has to have time to set and dry. Also if plaster of paris is used in your scenery give that time to dry too. BUT don't do anything yet. If you need to bring the sensitivity down first thing is to short two of the 4 shunting power diodes. Then you can also wiggle the collector resistors of the twin-t and the booster.

    Your'e doin' just fine. Now design your PC board. I think you mentioned one board for each Twin-T and one for each signal. If you need help I have a provisional layout that I can send you.

    P.
     
  8. MrDEB

    MrDEB Active Member

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    angies schematic

    look this over.
    I have 600 ohm for leds as the 470s were to small
     

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  9. angie1199

    angie1199 New Member

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    Yep, I changed them to 628R as suggested by Pete.

    I did find that if 12V ground and DCC ground are not connected the circuit doesn't work so there has to be some connection between the two.
     
  10. MrDEB

    MrDEB Active Member

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    proposed pc board

    if you have express pcb then I could Email you the files (schematic and pc board).
    then just print out on glossy photo paper using a laser printer.
    iron on and hopefully all transfers. A copy machine I think would work to but?
    you might get some distortion but layout has nothing real critical.
    second option = I will mail you a sheet or 2 of Pulsar paper with pattern printed on it. You iron and etch.
    option 3 contact express pcb and see how much for 25 30 boards.
    you might be surprised on cost.
    or contact a board company in UK. with PDF in hand they might be able to do it for you.
     

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  11. MrDEB

    MrDEB Active Member

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    $273.80 for 32 boards shipped to you in UK.U.S. dollars
    $49 is for shipping. local in the states its only ($9.95)
    I wonder if shipping to the states then shipping to UK would be cheaper?
    same board (16 per sheet x 2) is $237.90
    alot of drilling, 1100+ holes
     
  12. angie1199

    angie1199 New Member

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    Hi MrDEB, Could you send the PCB Express file(s) please. I can print from here. All's still working. Have tested it and left it on for quite a while and it's working ok.
     
  13. Raiway Pete

    Raiway Pete New Member

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    Angie

    Is the green current limiting resistor (R1) really 6K?

    P.
     
    Last edited: Dec 28, 2009
  14. Raiway Pete

    Raiway Pete New Member

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    Angie , MrDeb.

    Go to Home

    They have 8½ x 11 inch sheets that you transfer a mirror image onto. Then you iron the sheet (or a piece of it onto the PC board. You should get at least 12 copies of your twin-T on one sheet. I don't know about the signal driver though. You can get a five pack I think.

    Go to Ebay UK and search for "Press n peel'

    I use press n peel blue. I print a mirror image of my circuit board and iron it on the PCB. Then I etch.

    The cost for 5 letter size sheets is 8.50 (BP) + 1.70 for postage. The circuit board I have is small enough so that at least 12 per sheet. Then you will have 4 sheets left for your sig cntrlr.



    P
     
    Last edited: Dec 28, 2009
  15. MrDEB

    MrDEB Active Member

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    I myself use the PULSAR system
    PCB "Fab-In-A-Box" ... The 8min circuit board system
    have done .006 traces just for the fun of it and be able to say I did .006 traces. smallest that is usable for me is .020. sometimes .010 for between IC pins.
    the pc board I designed for Angi has all .040 seeng how she is new at this. Sen her one with a filled plane w/ .030 clearances. Saves on etchant. I understand Angiis using the dark brown icky stuff.
    I like the hydrogen peroxide/muratic acid mix.
     
  16. Raiway Pete

    Raiway Pete New Member

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    That peroxide/muratic acid stuff disolves concrete. Yow!! In England the transfer paper cost 9.99 BP. In the US it costs $13.80. The press and peel in the UK costs 8.70 BP (postage is 1.70 Hm.) I made a single board for our experiment. I just painted a PC board with green oil based paint and let it dry. Then I scored the circuit with a razor knife. Four ¼ inch stripes 4½ inches long and sectioned off. The board is about 1¼ inches wide. It can be made smaller because mine also included a signal driver. The etchant is the horrible icky stuff (ferric chloride). When depleted I use it as a yellow color base. Highly diluted it's great for taking the blueness out bof rocks. That's the story of the prototype. The circuit can easily be duplicated so that one letter size sheet can have about 20 Twin-T s on it for etching.

    For my Twin-T and signal controller board I just print a reverse image on paper, copy it to the blue film with other electronic designs to fill the sheet and then after cutting out an area I just iron it onto the PCB. I have foils that are about 5 mil. Seems ok. Sometimes edges are a bit ratty but as I'm not using high frequency logic that does not appear to be a problem.

    The icky stuff work well too because I have little undercutting. What I'd really like to do is to etch 3 mil brass for the signal parts. Got any ideas?

    P.
     
  17. Raiway Pete

    Raiway Pete New Member

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    Hi angie,

    Just a suggestion. But this is a board I put together using plain old oil based paint, letting it dry and then using a razor knife to cut the pattern. measurements are not critical.

    Pete
     

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  18. MrDEB

    MrDEB Active Member

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    what is this signal driver?
    the board I posted has the detection circuit and the 3 led signal circuit.
    the strip board idea is a lot simpler than the design I posted. I like the simplicity for ease of construction. Never tried the press and peel but have seen posts using and the pros and cons of using..
    I understand that Pulsar is selling their product in the UK at a reasonable price.
    I could have made the board design smaller but Angi is a newbi at this so I used wide traces. Looking at your strip board design, it might be easier for her but ??
    what software are you using to create the layouts you posted?
     
  19. condor36zw

    condor36zw New Member

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    Maybe something to consider..........

    Hi Folks. Been sort of following this thread, as I am a Model Rail enthusiast, who incedentally makes modules for the hobby commercially. Just a thought on the signal drivers, and use of relays and dim LEDs etc. etc. Quickly knocked up this idea which might be an idea for Angie to knock up and experiment with.
    It is based around the common RS Latch built around a CMOS 4011 I.C.
    The beauty about doing something around this basis, is that the circuit will latch (Set) and will only un-latch(Reset) when told to do so. The advantages of this is that you wont have problems with flickering LEDs from dirty track etc.
    Eliminating the leds and the 620Ω resistors on the output, one could even drive relay coils instead of LEDs.

    The circuit then has two spare NAND gates which can be used as an additional twin driver, or could be used as inverters i.e. as one LED turns on, another can turn off etc. I have taken the liberty of doing a schematic and a quick PCB layout, in mirrored and normal format. Angie, why don't you knock this up. Google one of the numerous articles on RS Flip Flops or Latches. If you need me to help on this, it would only be a pleasure.

    On the subject of boards. I always prototype using Epson Photo Paper, printing to the whiter side with a Laser, and then ironing straight onto the (thouroughly cleaned with rubbing alhohol) copper. I also sometimes iron on the silk screen side in the same way. Hence I have given you a mirror image of this layer aswell.

    If I can be of any help, let me know. Angie, if you need the schematics of my commercial detector, as well as the board layout, no problem. Just won't post it publically for obvious reasons. steve.verwey@vodamail.co.za:)

    Cheers

    Have a great day.
     

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  20. angie1199

    angie1199 New Member

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    Pete, MrDEB

    I thought hard about this and for the signals I will use a circuit board with both the detect and signalling circuits on one board, as mentioned in this message.

    http://www.electro-tech-online.com/threads/3-aspect-model-rr-signalling-help-plse.100094/#post828028

    However I can see that I may need a detector seperate for other things later in the build so a seperate detect circuit board is going to be necessary.

    Got your detect/signal circuit board files MrDEB, thankyou.

    I also have your detect only board Pete, thanks for that too.

    Now to build one of each and see what smoke if any there is.
     
  21. Raiway Pete

    Raiway Pete New Member

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    Dear Angie,

    I managed to log in. Now I have to change my password to something more logical.

    The board. I'm going to check if MrDeb's board can be cut into two separate mini boards, one sig cntrlr and one Twin-t. I suggest that you use a single design and then, by cutting and pasting the reverse image film to be ironed onto the PC board, put together a board that will do a specific job.

    CU Later

    pete
     

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