Reversing Loops

The problem is that the current through the reverse loop is changing from one rail to the other. If you draw your two rails with red and blue pens (or whatever colours you happen to have) you will find the red and blue meet in two places. That's calles a "short circuit". An insulated fishplate on each rail on the crossover will eliminate the short, until you run a train over the isolating fishplates! Fleischmann's answer is the two road crossings, each with two isolating joins and a diode. The train can then enter the crossover in one (arrowed) direction and depart back on to the oval after the controller is reversed.

There are other ways to wire the circuit, some simple and some complex, but the bottom line is that the controller has to be reversed for the loco to rejoin the main oval - unless you connect the controller to the cross-over track, place the double isolating rails on the outer oval and then solve the polarity problem on the oval :-)

Do the Hornby isolating rail pieces do the same as the fleischmann ones, ie with the diode etc ?

Ian

Greg.P. wrote:

Apparently no-one is going to answer this for you! I would doubt that Hornby "isolating rails" would be the same as Fleischmann (in function) However, there is nothing to stop you soldering diodes across the gaps to achieve the same effect. The diodes you would use would be type IN4001 or 2 or 3 etc. which will cost you a few pence each.

The "entry" isolating track should have the diode white/silver stripe on the exit end of the gap and the opposite rail will have it pointing the other way. The "exit" isolating track should have the diodes the other way around.

I have something like this:-

/------/---\---------------\ | |i |i | | |i |i | | |i |i | \-----/-----\--------------/

and I have no problems as the two sections marked (i) are completely isolated from the main lops and are fed via independent DCC reversing modules.

Reversing loops are dead easy with DCC.

Andrew

Ill second that... I had no problems with my layout and DCC. Still amazed how easy it all is Regards all Rob

It's even easier with analogue, and you'll have enough cash left over to buy another loco!

Regards, Greg.P.

In message , Greg.P. writes

No it isn't. At present, on my layout I can run a maximum of three trains independently without constantly throwing switches and a maximum of four trains if I do throw switches all the time, to make sure that each train stays with the same operator using the same controller. If I wanted to increase that number to ten or sixteen, the electrics would become unbearably complicated and cost a fortune in time if not money to build.

I am changing over to DCC. This means I can keep my layout's electrics as-is, which will give me a maximum of four independent power districts, and I can run up to twenty trains (counting each train as 1 amp and each booster as 5 amps, so maybe I could run more) simultaneously. No horrendous rewiring, etc.

"Greg.P." wrote

Got to disagree; just converted my largish layout to double track using DCC. The amount of time saved due to substantially reduced wiring is unbelievable, and not having to rely on dead sections to be able to isolate locos allows far more prototypical operation.

John.

Ok.

True, but if your layout can only handle 3 or 4 trains then why pay for un-needed capacity?

Good luck! We were (I thought) discussing reversing loop wiring. Whether we are operating DC or DCC the polarity needs to be changed as the train traverses the loop.

Regards, Greg.P.

I'm just wiring my layout now. I planned both analogue and DCC for comparison. The amount of wiring is much the same as every signal block has to be individually wired for detection.

That's the bit I'm going to miss in going DC. The cost of DCC and the constant loco addressing just doesn't justify the complication in comparison to a few sub-blocks and being limited to precise positions when stopping a loco.

Regards, Greg.P.

In message , Greg.P. writes

I have 1200 feet of track. The layout is 150 feet long by 30 feet wide. There are about 40 electrical sections each 30 feet long. That 3 or 4 trains was under the existing DC control, not under DCC.

With DCC you can buy a reversing section connector, which changes the polarity for you as soon as it detects the short-circuit. That is why reversing loops are easy with DCC.

That's close to 100 times the size of mine! I can run 4 trains without any problems

- I've got signals!

I agree that's going to be complex wiring, either way!

My layout has a staging yard of five single direction loops, (each with queuing) leading to a bi-directional double track main line with three crossovers followed by a mainline station and a single track exit at the other end looping back onto the main-line. Where do I put a DCC reversing module? There's five crossovers and a turnout where train shorts are possible. A DCC module would eliminate the possibility of unchipped locos running on the layout. It's far simpler to place DPDT switches on the relevant turnouts and have them select the correct polarity.

You should have used DC block control, then each driver could look after himself.

Not if you use DC block control.

Using my DC block control system your layout could handle 20 trains easily without extra blocks. My web page has the wiring details.

You will need to either use radio control or run wiring for your hand controllers. I don't think any DCC system can handle 20 radio hand controllers at the moment.

Over long distances you might loose the DCC signal. Heavier wiring might be needed. Not as critical with DC.

In message , Terry Flynn writes

My layout can handle 20 trains easily without extra blocks, considering I've got 40 blocks on the layout. I just don't want the hassle of having

20-way switches to ensure that I can control a single train on a single controller on its journey from one end of the layout, down the branch, around the main line loop, back up the branch to where it started from. DCC makes this much easier.

...

?????????

Forgery, "senior moment" or is there something that's been playing on your mind? :-)

In message , Chris Wilson writes

yes

That's probably because you were using DC cab control style wiring. Less wiring using DC block control. If you add signals, your wiring difference is minimal.

To date I have not come across one prototypical operation that I can not do using DC on my prototype based H0 layout. I do not intend simulating uncommon emergency type cases which DCC would allow. If I wanted to do this I would have wired the layout differently.

For a simple manually switched DC block system you don't need 20-way switches, just 20 on off switches which control signals for each block signal. A double pole double throw will give enough contacts for 2 aspect signals. Just one way of many that can do the job. At the other end of the DC technology scale, computer controlled systems will also do it all, no need for panel switches, similar to DCC, check out

.

In message , Terry Flynn writes

That's all very well, but what about controlling the locomotives independently of the signals? I have a handheld controller, and I want to control my train from one end of the layout to the other. So do all the other operators (up to 20) queueing up with their trains behind me. My controller has to be capable of connecting to every section on the layout, and so do all the others.