Thanks Larry I really appreciate all the Tech help that you provide to the Hobby, I personally would be lost without the sound Advice contained in your Videos. Keep safe.

Thank you for the information. I believe this is one of your best general topic videos.

Ahoj pěkné video pěkně vše vysvětlíš děkuji za tvoje videa a posílám mnoho pozdravů z České republiky Petr 👍👍👍👍👍👍👍👍

Thanks Larry, I consider your work the best in DCC

Hi Larry, thanks for a particularly illuminating video on a subject not often discussed and not always well understood. I am a recently retired Systems Engineer (electrical engineering and computer science) just beginning my journey into the world of DCC model railways. I have moved from the initial research phase into the "test track, prototyping phase". One of the key and surprising (for me) discoveries from my research and planning has been the reliance on deliberately short circuiting a railway (system) to achieve an outcome. e.g. detecting a short, then taking action. All of my SE background tells me to, wherever possible, design out the potential for a risk, in this case a short circuit. Where this is not possible, then design in as much system protection as is deemed mandatory for safety, both personnel and hardware. Circuit breakers (digital and analogue) are always the first line of defence. Modern command stations and boosters will typically include both up stream and down stream (towards the track) protection. e.g. a derailment on the far side of the layout. When encompassing additional CB's in the layout design, which I will do, it is important to ensure that the down stream protections are properly matched and that breakers will trip in the correct sequence and timing. My preference will always be "intelligent" solid state, fail safe breakers with a manual reset. With regard to turnouts or points, including crossings, then it pays to go for reliability for frog switching - it seems to me that a mechanical link between the turnout control mechanism and the frog polarity is often the simplest and most reliable methodology to adopt. I rely on the switch built into the point motor of choice, Tortoise, IP, MTB, etc.), for the DIYers and their servo controlled turnouts, then link a mechanical micro switch to the servo arm as well, to trip a relay to switch the polarity. (Not that I am a fan of mechanical relays, but they have their uses) With due respect to the manufacturers of the various "juicers", I will not use them. Never wait for the short, preempt it. As for reversing loops. Again, I cannot fathom why one would wait for the short to happen before switching the polarity of the rails, seems fundamentally wrong to me. We know there is a possibility (certainty) of a short occurring at one, if not both, ends of the loop. Why not detect the train/loco approaching the loop first. Then, if required, swap the polarity before the train/loco enters the loop. This can easily be achieved by having a sensor placed prior to the loop, or one at each approach to the loop for two way traffic. Once the train/loco is detected the polarity change can be triggered as required. In my case a use an Arduino type processor, with a very simple program installed, to sense the arrival and to change the polarity, as required, via a digital switch - not a a mechanical relay, as I said I am not a fan. If the loop is "controlled" by turnouts, then the turnout frog can be used to manage the polarity as described above. Sorry for the long post, but your great video inspired me to "stand up at the lectern again". Thanks again Larry - I enjoy your episodes.

I was just explaining to my son about cv values getting changed from running at our model railroad club. It's definitely important to realize that the power spikes can be detrimental to the decoder. I wanted to mention that I am glad to see you doing two videos a week again. Obviously it's going to be a lot of work, but it's going to be rewarding I'm sure.

For over 15 years, I've been running NCE 5 amp radio with 6 Frog Juicers (of various number of outputs) on an HO layout with many different manufacturers' decoders without any problems. YMMV

Thank you for sharing. Very much enjoyed. Good information that you share.👍👀

Great video, as always Larry!

Excellent video Larry, thank you.

I`m just getting into the hobby and your videos are extremely informative. Thanks

I agree with you about having to have these devices. I use the ar1, I have 2 of those and the cp6 circuit breaker. I'm glad things are available

Larry. Great video, very informative !. Pete.

Great information Larry I use all of the above

Good video! I have one of the 'new' Walthers 110' dcc turntables and it's 'autoreverser' for the bridge track utilizes a 'dead zone' to avoid the issue of shorts ===>> so it is even MORE important to have keep-lives in my locomotives that are big enough to 'bridge' the 'dead zone' on the turntable.

I have a small DCC layout with one power district. I know my Digtraxx Zephyr is a low end power/command station and has a circuit breaker, it has worked. Should I install a circuit breaker as described between my power feed and the Zephyr?

Many track insulators have a small pin that sticks up between the two rails being connected above the railhead. This lifts any single wheel above the rail to prevent high currents through the wheel. In the situation where the short is used to trip the reverser almost instantaneously in order to protect the electronics it is probably better to have the single wheel do the shorting. If a lead wheel is prevented from operating the reverser the short won't happen until it has to flow through a pickup, through internal wiring, and out through another pickup and wheel. This will bring the large current and potential surges right into the pickups and wiring near the decoder. A razor knife will help you cut out the raised pin and let any arcing happen when the first wheel hits the open gap.

Speaking of voltage spikes, how do you feel about RC Filters (aka "Snubbers)? Some see them as band-aids but I plan to use them just to be safe.

Also I use a on /on toggle switch on an isolated section to reverse polarity no stalls unless I forget to through the switch so I'm always watching my trains.

Quite an interesting video - I watched it all the way through! My layout is all insulfrogs with no reversing loop, so I think I made the right design decision. I think I might create a presentation in PowerPoint for your videos. Although someone like me would know what you are talking about, the notion of a frog juicer would be lost on most of your viewers. Keep the videos coming. Thanks for uploading.

Very interesting, Larry. Surely it should be incumbent on the manufacturers of the "command stations" to include software/hardware that prevents the massive spikes? Or at least there should be something that you can put between the central command station and your bus that can limit spikes? Have to admit that I didn't entirely understand why you get those spikes when there's a short, so I might have the wrong end of the stick here. In ye olden days of DC, we used diodes over the insulated rail joiners at the exit end of a reverse loop, and then it was a simple matter of reversing the polarity as the loco went over the gap. I guess that, as DCC doesn't have polarities, that sort of manual solution wouldn't work with DCC?

I use two separate independent systems for reversing loops. 1.) Two photo detectors just a few inches beyond the frog on each of the branches detect if *_any_* part of the train is on that bit of track and throws the switch (turnout) to the branch that is occupied (okay, both branches are technically occupied if it's a loop, but you know what I mean...). 2.) Two isolated track sections just beyond the frog on each switch detect current draw (i.e. a locomotive only) and reverse the polarity on the main part of the loop to match the section containing the locomotive. This works perfectly whether the locomotive is pulling or pushing the train, in the middle, or even multiple locomotives at different parts of the train.

A little new to your channel. Great video. I understand the pro's and cons to autoreversers. I agree with you on layout design and limiting reverse loops. But wouldn't it be better to have transponder in the locomotive to tell the autoreversers to switch polarity coming out of a reverse loop in advance of the locomotive? I use Digitrax decoders because it has transponding built in and works with SurroundTrax by SoundTrax for layout sound (when it's done ).

To avoid runway locos take the DC function off the decoders change CV-29 to 34 for forward or 35 for backward. I've had that problem in the past but not since I've changed the CV values to34.

In my opinion a frog circuit is a waist of money. All you need to do is use a switch machine with contacts or even simply add a SPDT switch to the throw and wire the frog to automatically change polarity when the turn out is thrown. Cheap and easy. Same can be done with the reverse loop, A DPDT switch attached to the turn out throw allows you to change the polarity of the loop depending on the direction the turn out is thrown. Zero shorts or possible issues.

Howzit Larry : Notwithstanding electrons strolling around * Near The Speed-of-Light; * it has been my understanding over the years that these * Short-Circuit Reactive * units are designed to detect the problem BEFORE the actual control DCC-System is aware of the short; thus lending protection to both Decoders and the System. But ultimately; the short occurrs as you described in detail. In finally getting to my questions : [ 1 ] Given the carrier-voltage and usual 5-8 Amp rating; there surely has to be a nano ( ? )-spark that is generated every time across the gap ( s ). Does this not create spark-erosion pitting of the wheel-tread that must lead to eventual poor pick-up / electrical continuity ? [ 2 ] In successfully using Auto-Reversers + Circuit-Breakers + Frog-Juciers on my Layouts; does close proximity in placing these units near the scene of the crime play an important role by way of promoting optimum performance ? Much Thanks for your informative Series and Cheers For Now / Johnny

Hey Larry, the automatic reversers are a well thing but making problems sometimes to the direction of travel of digitalisized locos after they run through a reversing loop, a reversing triangle or using a turntable. What about consisting them after the locos run through a reversing loop than they are probably in wrong direction? Would they not need to get changed the regulary direction of travel in CV 29 bit 1?

Another great video. I have noticed that every autoreverser except one manufacturer detects a short circuit to initiate the phase reversal. And I agree this is a downside of AR's. Digikeijs uses a sensing track at the inlet and the outlet, then changes phase before entry into the reversing section. This seemed like a better way and I was wondering if you had any opportunity to look at this item?

Larry, thank you for the video. What are your thoughts on the Digitrax PM74? 4 district Power Manager, AR and occupancy detector. It replaces the PM42. I appreciate all your informative videos.

I am considering using the Digitrax BXPA1. I would be interesting on your opinion of it. Both Tom (Tom's Trains and Things) and Charlie Bishop have commented on and are using them. Model Railroader did a review, October 2021. The instructions with the device are sorry lacking. Secondly, I would be interested in a discussion of transponders.

I like the frog juicers. They simplify wiring especially for track like double x overs. I've been using them to power all my frogs for over a decade and they've been working flawlessly.

Hey Larry! I thought you said you retired from making videos! Couldn't stay away from the hobby, eh? Welcome back! :-)

Hi Larry. I have a Digitrax "DCS210+ Command Station/Booster With Intelligent AutoReverse" that came in the EVOX Evolution Express Advanced starter set. Does this not incorporate circuit breaker technology? Also, my point (turnout) motors are DCCconcepts Cobalt iP Digital; will these suffer from the same problems as the frog juicer(s) that you mention, even though the circuitry is built in?

G'day Larry, I use a dual frog juicer for a turntable polarity changer, but all points are manually activated via a rod system which uses a slide switch to cha ge frog polarity, do you feel I should included some form of circuit protection, thanks for all the videos and information, always watching from Australia. Cheers.

Great vid. Funny as auto reversing is an application I’m working on. Ignorant question; the area that’ll be controlled by the auto reverser, do you still connect your feeds the same as the rest of the track that’s outside of the reverse application…?

Will the DCC concepts snubbers mitigate the voltage spikes that you discussed in this video?

I am in process of designing an 8 x 14 ft layout (shelf). Probably one level. I am thinking it will be two circular loops with a flip up bridge to enter the room. Industry and small yards mostly on one of the loops. Should you figure on two blocks?

I'm so confused. I want to start construction on my ho layout but can't seem to get my head around switching. I'll definitely be using the NCE system I've already purchased. I have several thousand invested over the last 3 years in power, rolling stock, track and switches, but still don't have a complete understanding of switch / track control, so I havnt purchased any of the turnout control, accessory decoders - autoreversers, ect. I will set up a control panel with momentary buttons for switches and plan to use Tortise machines with decoders, but, if the Tortise machines are capable of correcting polarity, I'm not really getting the need for having to add the auto-reversing. Even after watching countless video offerings on the subject and not getting it, I feel I have developed a mental block with this subject. If anyone could shed some light on this for me, I'd be forever indebted. The couple dozen switches I have can all easily be powered or non-powered. I know I have done things backwards but have no local inspiration or mentor & probably bought track I'll regret but Ive been buying a little each month in order to have the matetials to create a decent size layout when the time comes but I have so much of it now that I will absolutely use it and transition to something better as I need to grow the layout but all of the track / switches I have purchased to date is Kato and there is close to 80' of it including switches now, so Im stuck with it. I am getting excited to start building now but still have a lot of equipment to get just to run the loops / switches as intended so I've got to resolve this soon. Cheers and thanks for any input anyone cares to offer. RB.

Besides protecting against shorts, don’t devices like the psxx help with power on problems with multiple sound locos on a single block?

Can you put a ir detector at the beginning of the loop and switch polarity before the train hits the section?

Do these devices have a curent draw when not reacting to a spikce in current? Also, it would be helpful to know where the short is occuring, not simply block the spike. So how do I do this? I very much appreciate your work. Best regards,

I have over 30 Frog Juicers on my small n-scale layout and haven't had any known issues

Hi Larry, I have a question for you, witch circuit breaker should I used with my NCE power cab; NCE or DCC specialties

Hi I use the frog juicers but was woundering if they can also run leds to show what track is open ( main or divergent route ) thanks

What about using TVS diodes to clamp or stop the voltage spikes? A lot of the # rail guys use them. Not sure what size you would need or if they could affect DCC operation.

Reversing loops and frog juicers do not need to operate on shorts. Systems can be set up that operate on relays set before the loco run through. The loco doesn't get the green signal till the system is set. No shorts at all!

I understand you have a wiring book . Where can I buy that book. I'm in the U.S.A. if that makes a difference.

How about putting an 1156 bulb in line to absorb the voltage spikes?

Will rc absorption snubbers help control the voltage spikes? After watching your video on snubbers, I found and purchased some on ebay that supposedly help minimize relay contact spikes. They have a large current resistor and high voltage capacitor similar to what you described in your video on snubbers. They also contain a MOV varistor for extra protection. Conveniently, they have terminals for wiring. Finally, they are also cheap!!

The potential "short circuit" that I am now focused on would be occurring when a turntable rotates my locomotive, changing its direction. Since I use DCC for control and sound effects I need to minimize these shorts. As I researched this situation the PSX-AR seemed to be the correct choice. I am just now starting a new layout so I haven't seen it work yet. Can anyone tell me if it works as I hope?

I've been using dozens of frog juicers and about ten of the ARSC auto reversers for years on my Digitrax Super Chief system with 12 boosters without any problem. I'm finding Tortoise contacts extremely unreliable and would not use them for power routing or frog control. All my locos have "DC operation" removed in their programming so those runaways mentioned don't happen on my layout. Thanks for the brain food but I see no reason to abandon my practices. These electronics are making DCC operations a breeze.

is there a wifi train model availble?

So in the end: What's inconvenient about these devices ? The only advise I see is to add a switch to a circuit breaker to re-power a shorted section manually. But that is part of the install instructions.

Or you could just get a Lionel 3 rail system which has no such problems

Anything that relies on a short circuit to function should be forbidden, there are solutions that are based on occupancy thereby avoiding short circuits.

Hi Guy How Are You Doing Today We Are Doing Great Today And Ho N Mark O L Amc Flyer

I don't savvy !.. If I have one reverse loop of track on a DCC controlled system are you saying that the one AR and rails correctly gapped for it is still potentially going to fry my decoder or, at least, change CV values when rolling into or out of said reversing section ? I think most who open this video are concerned with THIS as opposed to the OTHER items used for short circuits and overloads you're citing... In other words, I don't think, for simple reversing loop track and the AR which controls it, there is anything to worry about or these devises would have been dumped long ago. You seem to be creating fear, at least for simple reversing sections in DCC, where there need be none..