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Post by Deleted on Apr 16, 2017 0:41:10 GMT -5
The most recent idea : a circuit breaker using a simple relay (not yet tested) ; the "voltage reduction" diodes should only be used if Vcc is too high for the coil and could be replaced with one Zener diode in case of a "very big" difference ; I think that this circuit breaker should not be triggered by power "spikes", only in case of a real short circuit ; and I read that reaction time of relays is less than 50ms. What do You think about it ?
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Post by Deleted on Apr 16, 2017 14:45:11 GMT -5
I want to shut down power supply to the tracks if a short circuit is caused by a locomotive running into a turnout that could be set to the wrong position by a malfunction (but I think this is not very likely to happen ... ) So the whole "chain" where the short current could run through would be protected : the PCB in the locomotive AND the contact systems in the turnouts ! And additionnally the power supply would be protected, too ...
About BAZman's last post : perhaps this supplementary protection is unnecessary with some regulators ? Or are 2 precautions better than one alone ?
About protection for the coils : the principle itself of capacitive discharge protects them ; and I hope it's very unlikely that an electrolytic capacitor becomes short-circuited under normal use conditions (I saw it once, more than 30 years ago, but with a tantalum capacitor) !
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Post by BAZman on Apr 16, 2017 16:20:20 GMT -5
With the gauge tolerance (or should I say more deviation tolerance), you are going to find that just flipping turnouts, steam locos running through a turnout and current surges from DCC decoders placed on the track, vintage trains with incandescent bulbs are all going to have transient 'shorts' or surge currents. Then you get into the higher currents of the MTL F7 and märklin permanent magnet motors building a threshold much closer to the trip current, whether the 'average' current or the *much* larger transient currents (from the *much* higher transient voltages (50-200 volts is NOT uncommon), compared to the *much* lower currents of the coreless motors. BTW: the DCC Specialties PSX series has a CV that can be set to enable Manual reset.
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Post by Deleted on Apr 16, 2017 16:43:05 GMT -5
To BAZman : 1) I will use only DC locomotives, NO DCC ! My layout wil be wired in "traditional" (old fashioned ? ) way, WITHOUT ANY DCC DECODERS , but with capacitive discharge (like the Kato system) for turnouts : 7.5v and 1500uF for each turnout, and perhaps PWM speed control (or variable voltage ? ). 2) And no locomotives with bulbs, no Märklin or steam locomotives : only one passenger train with 2 RDC's in MU configuration, two freight trains with a GP7 and a GP9, all locomotives built by AZL (cars by MTL and "Full Throttle" ), so I assume they have coreless motors. 3) The turnouts will be powered by their own supply (together with the 6v relays, these via 2 or 3 silicon diodes in series to reduce the voltage) ; and the microcontrollers will need a third supply. The only devices powered by the "trains" supply will be the trains themselves, and the detecting circuits for the track sections (with LM 339/393) ; and power to the tracks will be off during "direct/reverse" switching by the relays and flipping turnouts, to avoid transients. 4) So the most problems You mentionned won't occur ! To Greg : I saw another very simple current limiter here : www.zen22142.zen.co.uk/ronj/add-on.htmlPerhaps this could be an additional protection, upstream from my "relay breaker" ?
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Post by Deleted on Apr 17, 2017 0:46:00 GMT -5
Must I assume that Z locos and turnouts are SO delicate, and that Z was a bad choice ? On my former N-layout I had never such problems, and it was protected only by fuses ! On a german site : k.f.geering.info/modellbahn/technik/dccsicherungsautomat.htm , I saw that the author switched the current (limited "only" to 2A with DCC per section) off after ... 0,25s ! So I wonder if a limitation to a safe 100~200 mA or less per train (there will be 2 sections with only one train) and a fuse would not be sufficient ? On another site (for N : www.1zu160.net/scripte/forum/forum_show.php?id=556699) I saw a trick with a 21W bulb (automobile "brake" light) in series, and it seems that this old idea works ! The author wrote that this system is often forgotten todays, when most people are thinking only of electronic solutions. And that such a system is still used in loudspeaker boxes by JBL (!) to prevent overloading. Perhaps the voltage of the bulb must be modified for the lower voltage used in Z (Osram 8v 20W halogen, not cheap, about half the price for a turnout, but if it is effective ... ) ? My question is now simple : what is the maximum short circuit current that the locos and turnouts can accept during a short lap of time without getting permanently damaged ? I hope it is more than the normal running (I hope even twice, because RDC's are coupled in MU) current. I don't wanna make a "destructive" test ...
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Post by Rob Albritton on Apr 17, 2017 6:10:05 GMT -5
Hi Guys,
A few observations regarding this conversation:
1) With regard to electricity: Z scale Is just as delicate as N scale. Z scale is also just as strong as N scale. Electrons know no scale. All of the same tricks and techniques used in N scale will also work in Z scale. All of the locomotives we have made in the past 5 years are 100% compatible with N scale electronics, voltages, and settings. 2) alberich seems to be working on a small to medium size layout with D.C. Power and less than 10 locomotives. This is wonderful as it is a great way to experiment with Z scale and get addicted. Much of the advice regarding short circuits and capacitive discharge equipment really applies to much larger DCC layouts with 10 or more locomotives running in hidden sections. These larger layouts (like mine!) have locations where derailments can happen - almost exclusively on turnouts - that cause a short circuit, and yet they are not noticed for several *minutes* yet the DCC power does not trip off, leading to burn out decoders or melted locomotive wheel sets. This is a very very different environment than alberich plans. 3) our locomotives are designed to withstand short circuits of several seconds under DC power without a problem or damage. Certainly long enough for an operator To turn off the power pack or remove the derailed locomotive. This makes perfect sense,as it is the way that the vast majority of our customers run their trains. If it were not true we would have burnt out locomotives being returned to us under warranty all the time. We do not. 4) may I suggest you start with a simple solution like a 12 volt automotive light bulb? I think you will be more than happy with that elegant and easy solution. Beside, we are all Edgar to hear your tales of layout construction, and I think more than enough time and energy has gone into the electronics department! ;-)
Best regards Rob(A) AZL
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Post by Deleted on Apr 17, 2017 8:49:13 GMT -5
Thank You Rob ... The layout will be 2.9m x 1.45m, with 2 VISIBLE stations, each with two tracks (only one for passengers, i.e. the Budd's) and 1 or perhaps 2 "dead end" freight tracks (6 or 8 turnouts). They will be linked on each side with a single track going from one end of the layout to the other and back, about 7 to 8m long (I didn't yet measure exactly on my plan, only the critical sections to ensure vertical clearance), 3 tunnels and 2 bridges. So the layout will TOPOLOGICALLY be a simple oval. The general shape is the same as my former N layout (3.2m x 1.8m), the main difference is that it was built with "double track", 16 block sections and that even TEE's and a french TGV (Lima) were running on it ! My new one will have more "local" rural (and so, realistic) character, with only about 20, maximum 30 buildings (former : about 45~50, a trolleybus line, a locomotive depot, a never used container terminal and even an "aerial cable car" by Brawa) ; i.e. a SMALL village and a SMALL town, and more forests and meadows ; most layouts I saw on exhibitions in Europe are NOT mainline layouts. It was usual in the 80's to overload layouts and make them look like demos in the shop windows at Christmas ; I think that in this context, "less is more". And, despite of the fact that most functions will be automated, I will not let it run "alone". So I am now waiting for my rolling stock (already ordered), to ensure that my planned clearance in curves (+/- 15mm) will be large enough, build a test oval for "break in" and some electronic tests, and then I will begin with building. I will publish a photo when the first step is finished, i.e. infrastructure and tracks (I hope before winter) ; and then I will test it extensively to ensure that there are no problems with the tracks, causing derailments (Murphy says : in tunnels), and next year I will finish with the landscape (hills made with Roofmate).
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Post by smr on Apr 17, 2017 10:31:37 GMT -5
Thank You Rob ... The layout will be 2.9m x 1.45m, with 2 VISIBLE stations, each with two tracks (only one for passengers, i.e. the Budd's) and 1 or perhaps 2 "dead end" freight tracks (6 or 8 turnouts). They will be linked on each side with a single track going from one end of the layout to the other and back, about 7 to 8m long (I didn't yet measure exactly on my plan, only the critical sections to ensure vertical clearance), 3 tunnels and 2 bridges. So the layout will TOPOLOGICALLY be a simple oval. The general shape is the same as my former N layout (3.2m x 1.8m), the main difference is that it was built with "double track", 16 block sections and that even TEE's and a french TGV (Lima) were running on it ! My new one will have more "local" rural (and so, realistic) character, with only about 25, maximum 30 buildings (former : about 50, a trolleybus line, and even an "aerial cable car" by Brawa) ; i.e. a SMALL village and a SMALL town, and more forests and meadows ; most layouts I saw on exhibitions in Europe are NOT mainline layouts. It was usual in the 80's to overload layouts and make them look like demos in the shop windows at Christmas ; I think that in this context, "less is more". And, despite of the fact that most functions will be automated, I will not let it run "alone". So I am now waiting for my rolling stock (already ordered), to ensure that my planned clearance in curves (+/- 15mm) will be large enough, build a test oval for "break in" and some electronic tests, and then I will begin with building. I will publish a photo when the first step is finished, i.e. infrastructure and tracks (I hope before winter) ; and then I will test it extensively to ensure that there are no problems with the tracks, causing derailments (Murphy says : in tunnels), and next year I will finish with the landscape (hills made with Roofmate). Hi Alberich, You may want to take a look at my really SIMPLE OVAL. It is much smaller with just 1m x 1m, but may serve as a good source for inspiration especially when it comes to landscaping. azlforum.com/post/7221/threadAll tracks are Rokuhan. Built in 2013, no problems until today ;-) !! Have fun, Best, Sven PS: To Greg: just one power supply - you can switch between digital and analog - up to six engines running in parallel (AZL, Freudenreich, SMZ, or Maerklin) - no problems with switches or lights after heavy testing before building them permanently into the layout.
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Post by Deleted on Apr 17, 2017 14:14:46 GMT -5
Greg, You are speaking of 5 Amps during 2 seconds ; in my case this could not occur ; as I read AZL locos run with very low current, not even 200mA ; so if I limit the current to 400mA (don't forget the Budd's) per section (by any method, the simplest being the best), the "horrific" values You indicate in Your post can't be reached in my case ... with or without the bulb, and even my relay breaker will trigger fast enough. And I think Rob is right when he says that with usual values the danger is not so great (the melted springs shown by our German modeller friend in the turnout came from DCC) ! So this discussion comes away from my personal problems, it would rather concern a DCC environment where such values are usual because more than 1 or 2 locos per section should be powered, and as I wrote, I will NEVER use DCC ! All the way I didn't want to start a "troll", and this is what this topic is becoming ...
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Post by Deleted on Apr 17, 2017 15:27:31 GMT -5
To Sven : 2 pictures from my former layout. Attachments:
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Post by Deleted on Apr 17, 2017 15:28:39 GMT -5
And two more pictures ... I think that especially the "village" looks a bit overloaded. For the new layout I will keep the overall shape (but only single track), simplify the stations, remove the locomotive depot and the container terminal. The bridge will be moved to the right, so I can put a longer straight track (about 28cm) between the two curves left of it ; although there was no technical problem, it looks better. The tunnel entrance behind the bridge will move to the back, so there will be a second bridge and less tracks in tunnels ... And the overall shape of landscape will be almost the same, too (but not so high and with less boulders : it's in Massachusetts, not in the Rockies or the Sierra Nevada) Attachments:
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Post by Deleted on Apr 17, 2017 20:08:30 GMT -5
It was an answer to smr ...
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Post by Deleted on Apr 20, 2017 15:02:32 GMT -5
"smr" wanted to help me and show a proposal for a layout. I only wanted to answer and show him what I was already planning ... I didn't wanna offend anybody. Sorry if the topic "derailed" !
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Post by Commodore on Apr 20, 2017 21:11:22 GMT -5
Greg:
Have you seen BoxcarWilly?
He's not on any thread...
I've looked everywhere!
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