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555 Timers
Forum Analysis of a 555 circuit design, will it work, maybe there is a better way
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Forum Thread Details
  • State Not Answered
  • Replies 24 replies
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  • 555 timer
  • circuit design
Related

Analysis of a 555 circuit design, will it work, maybe there is a better way

colporteur
colporteur 11 months ago

I'm looking to build an End of Train (EOT) circuit. The model railroad folks I hang out with, just purchased a commercial unit. After gagging at the price, I figured why not build one.

My search found this resource https://techlib.com/area_50/Readers/Lennie/End%20of%20Train-1.pdf complete with PCB. Unfortunately all the links are dead so I had to generate a schematic from the PCB layout.

image

Question: Will the circuit work? Are there any reasons for the design?

Instead of bread boarding the design I figured the folks that hang out here are great and offering solutions. Tapping into the experience of the members surely helps. Nothing like experience to find a solution fast.

image

I have some concerns with the circuit. I couldn't found a 555 circuit that uses pin 7 as an output. I took a look through Cabe Force Essential 555 IC book (Cabe hangs out here:) and found nothing like this beast.

I'm not sure of the design. It looks like nothing I have found.

I'm thinking it would have been easier to just start from scratch. 

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  • scottiebabe
    scottiebabe 11 months ago +3
    Perhaps pin 1 is here?
  • beacon_dave
    beacon_dave 11 months ago +3
    colporteur said: Unfortunately all the links are dead so I had to generate a schematic from the PCB layout. Flashing Rear-End Device For DCC Systems https://web.archive.org/web/20140926093814/http…
  • dougw
    dougw 11 months ago +2
    What flashing rate do you need? You can buy LEDs that automatically flash:  PRO SIGNAL PSG91916 If you need other rates you could try: https://evandesigns.com/products/flashing-leds-for-hobbies…
Parents
  • beacon_dave
    0 beacon_dave 11 months ago
    colporteur said:
    Unfortunately all the links are dead so I had to generate a schematic from the PCB layout.

    Flashing Rear-End Device For DCC Systems

    image

    https://web.archive.org/web/20140926093814/http://home.cogeco.ca/~rpaisley4/FredDCC.html

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  • shabaz
    0 shabaz 11 months ago in reply to beacon_dave

    Very useful; indicates that the duty cycle needs to be about 10% at approx. 1 Hz. I suspect train enthusiasts do want it to be close to reality, so that's likely a hard requirement, at least that ballpark anyway.

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  • shabaz
    0 shabaz 11 months ago in reply to beacon_dave

    Very useful; indicates that the duty cycle needs to be about 10% at approx. 1 Hz. I suspect train enthusiasts do want it to be close to reality, so that's likely a hard requirement, at least that ballpark anyway.

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  • Jan Cumps
    0 Jan Cumps 11 months ago in reply to shabaz

    I think that the timings on the schematic are based on the circuit components, not on the regulations of USA train companies.

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  • beacon_dave
    0 beacon_dave 11 months ago in reply to shabaz
    shabaz said:
    I suspect train enthusiasts do want it to be close to reality

    The real ones appear to also monitor brake line pressure and use wireless telemetry to send this information back to the lead engine. Oh, and they are battery powered in a self-contained portable unit. Slight smile

    I hope this model railroad isn't N-gauge ! 

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  • Jan Cumps
    0 Jan Cumps 11 months ago in reply to beacon_dave

    I'm an HO fanboy Slight smile. As child, I had Jouef trains.

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  • shabaz
    0 shabaz 11 months ago in reply to beacon_dave

    Surprisingly difficult finding a YouTube video showing that device blinking. Watched a couple of instructional videos explaining what it does, and I've learned how to install it however Slight smile

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  • beacon_dave
    0 beacon_dave 11 months ago in reply to shabaz
    shabaz said:
    Surprisingly difficult finding a YouTube video showing that device blinking.


    https://youtu.be/SrYin24eBmc?t=411

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  • Jan Cumps
    0 Jan Cumps 11 months ago in reply to beacon_dave

    Once, while driving through Antioch, Illinois, I had to wait for a big looooong freight train to pass by. 
    If only I knew that this device was used then ...

    It's not used over here.

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  • shabaz
    0 shabaz 11 months ago in reply to beacon_dave

    (I mean on a real train! : )

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  • beacon_dave
    0 beacon_dave 11 months ago in reply to shabaz

    I think there is a photocell that only turns them on in low light

    https://youtu.be/fE9Y2Pqdwig?t=8

    https://youtu.be/LJ_kQLihI3k?t=147

    https://youtu.be/d1CnNQ97qKo?t=21

    https://www.youtube.com/watch?v=lc_DuOgA5vM

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  • Jan Cumps
    0 Jan Cumps 11 months ago in reply to beacon_dave

    I read the specs, and that's true. They usually run on a battery, and have a light detector to save energy.

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  • shabaz
    0 shabaz 11 months ago in reply to beacon_dave

    Ah, good to see. I watched the first couple. Looks like they exhibit a low duty cycle (or perhaps it changes for different events).

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