Toggle switches degrade DCS Signal?

You never really know  sometimes until you try different things.. Sometimes if you have  seperate feeds with toggle  from the terminal block  to the 2 sections  it works, other times if you feed a section directly  from a know good source (main line ) it also works.

 

Sometimes nothing works 

A spare TIU channel   comes in handy for times like this. Each channel has a signal generator. I don't think the toggle is the problem.

Layout is a single track with 3 passing sidings controlled by SPST toggles. Power is a ZW.

 

Power wires are in a Y configuration, with the stem of the Y originating at the ZW, then one arm of the Y goes to the TIU, then to track; the other arm of the Y goes to track. Both are fused. I run only one engine at a time, so the locos are either TMCC/Legacy, or my one PS-2 cab foward.

 

I'm only using one TIU channel (Rev L, btw). Could you provide wiring suggestions?

 

If the main line center rail is connected directly to the center rail of one of the toggled sections, DCS signal comes back up, which is what led me to believe the toggle is causing signal degradation.

 

If a second TIU channel is used only for these 2 sections of track, what needs to happen with the handheld control and engine - will they see the second channel and transition smoothly from the main line (channel 1) to the 2 sections using the second channel?  Or must the handheld and engine be programmed to see the 2nd channel?

Phil,

 

Try this...

 

With the toggle switches off, jumper across their contacts and see if signal strength improves. If it does, replace the toggles with a better brand.

Hi Barry,  yes, what you described does happen. I just posted that and then saw your reply. I'm using some Carling spst toggles; I think they're Radio Shack.  I've searched for spst toggles but uncertain as to their quality. I believe a mil spec toggle would be better, but where to find?

Phil,

 

I have close to 100 toggle switches on my layout and most are from Radio Shack. I have zero problems with them.

Shouldn't this test be with the toggle switches ON, jumper across their contacts? 

I think jumpering with the switch "on" would introduce another variable.

I just jumpered the center rails from the main line to the toggled section. Doing this made the DCS signal improve.

Shouldn't this test be with the toggle switches ON, jumper across their contacts?

No, the idea is to to bypass the switch as if it wasn't there.

I just jumpered the center rails from the main line to the toggled section. Doing this made the DCS signal improve.

That's not good enough to identify the switch as the problem. You bypassed all of the wiring between the TIU channel and the track block. The problem could be anywhere in between.

First off, I have no real experience with this issue so consider that with respect to the post.

 

I have been considering a similar design.  Here is my theory.  Routing the power to the panel switch and then to the track introduces extra wiring and probably breaks the "star" wiring rule (I know some people don't use it but there seems to be some consensus that it is the best approach for signal).  I plan to mount a relay near the source of the TIU on the theory that this would be a minor disruption to the star configuration and then run a 12v control wiring circuit to the toggle switch on the panel to control the relay.

 

Again, no proof this is a good idea, but seemed to make sense to me given all I have read about DCS reflection issues.

 

Gene

Phil, place an 18-volt bulb across the toggled block & see what happens to signal strength.  Also, place a loco outside the block, and turn the toggle switch on & off:  does the signal strength change.

I believe that a Carling switch is considered good quality.  It is a name brand.

I bought a bunch of miniature switched from Allied some years ago & have had no switch problems.  Frankly, if a switch is able to carry current for train operation withou voltage drop, I would think it is capable of carrying the DCS signal.

If a second TIU channel is used only for these 2 sections of track, what needs to happen with the handheld control and engine - will they see the second channel and transition smoothly from the main line (channel 1) to the 2 sections using the second channel?  Or must the handheld and engine be programmed to see the 2nd channel?

 

Nothing needs to happen to the remote & engine. The engines will see the second channel (dcs signal)  and transit smoothly. our layout is single track and transits over 16 channels with no problems,

 

 You can even use the same ZW handle for power    All you have to do is..... Jumper fixed 1 IN over to Fixed 2 IN and fixed 2 out to the Toggled  sidings, Guaranteed fix.

 

Some are going to say that's not necessary and  are correct  but this is pretty easy to do and  why not have 2 signal generators working for you rather than one. You should have a perfect dcs signal doing this.

But if you jumper the switch while "on", you have immediate, verifiable information available to show just how much signal is lost through the switch contacts.

 

Switch on, check signal, jump switch, check signal difference.

But if you jumper the switch while "on", you have immediate, verifiable information available to show just how much signal is lost through the switch contacts.

We already know what is the effect of having the switch set "on". By testing with the switch set "off" we learn the effect of bypassing the switch. If there's still a problem, we know it's not because of the switch.

 

It's necessary to test with the switch out of the circuit.

I am interested in this discussion of signal strength, as I am getting unsatisfactory results on our modular layout. We use toggle switches.

Here is how we have it wired

Blueline:  The output from each of my 6 TIU red outputs is fed to a portion of my control panel, where it goes from toggle switch to toggle switch to toggle switch, as many 1s 10-15.  The other terminal of each toggle switch outputs to individual track blocks via 14-gauge wire.

TIU black outputs are all joined and fed into the common bus that loops around my layout. (Nothing is connected to black inputs).  A few [not all, and no rhyme or reason for which] dead end sidings needed 18-volt bulbs to keep from pulling signal srrength in other blocks.  The whole layout, 39x16, works great.

Bottom line, buy good switches and minimize any problems.  Also do the test Barry told you about and you will know if your switch is the issue.  I have replaced many switches on many large layouts for just that signal problem.  I have a very large number of switches on my layout and have no signal  problems due to switches.  Some of them are almost 30 years old.  Some guys have a bit of luck with lower end switches and most do not.  I have switches that are powering sidings 70 feet away. 

 

You might want to ask the guys that build the large layouts this question.  They will tell you what to use and what not to use.  I am thinking of Dave Heikel, Rich Roman and Michael Hart (SMARTT) .  This subject comes up often and everyone has a different twist on what is better. 

Marty, question:  When you have replaced switches for signal problem, have you ever tested the switches after removal by placing them under a heavy load, say 7 amp, and checking for voltage drop across the contacts?  If a switch has been replaced for a signal diminution problem, and does not show any voltage drop across the contact, it would be an interesting endeavor to find out what caused the switch to behave as it did.

RJR, quick answer is no.  When working on large layouts , the goal is to make things work and move on.  As I stated, I have removed many switches that degrade signal and do this after the foolproof test Barry outlined.  If you get degraded signal and it jumps up with the jumper on the switch, replace it. 

'

You bring up a good point.  When I am back in action (I hope) I will do what you suggested with a removed switch on my dime.  When someone is paying decent money for you to wire his layout, he does not care about the problem switch nor does he want you to fool with it while the meter is running.  R and R.

 

I feel with lesser quality switches the killer is keeping the heat on the contact longer than it should be present. 

 

I am a huge fan of good quality rotary switches if you have a larger number of sidings.  DCS loves a good switch.

We use house hold wall electrical switches(lights) rated at 120 volts , I forget how many amps? They're a bit  on the large size but cheap and    work well.

 

Don't forget my post about using your spare tiu channel. (Guaranteed fix) 2 signal generators are better than one.

When I installed all the electrical wiring under my layout, I installed toggle switches for every track in the roundhouse area, the freight yard, and the rural area sidings. I ordered the toggles from a local electrical supply house/wholesale supplier for electrical contractors. This is the brand I used:

 

"Selecta Switch"  rating: 16 amp @ 125V ac/dc, screw terminals, 1/2" diameter mounting hole.

 

They company was in California, and there is an 800 phone number on each bag containing one toggle;  800-722-6445

 

I have NEVER had ANY issues with DCS, nor TMCC/Lagecy.

This is a test for GGG.

Marty,

   Your advise long ago about the MTH street lights in front of each good toggle switch

has always worked for me, with both I have never had a problem with any of the sidings I have engineered.

PCRR/Dave

Well, my topic certainly generated lots of replies! I took Gregg's advice, bridged Fixed 1 IN to Fixed 2 IN, then used Fixed 2 OUT to the power wire that branched off to the 3 toggle switches that controlled the 3 through sidings (I disconnected that power wire from its source wire), while using common ground. Happily, the DCS signal has now become a 10 since the tracks are now on another DCS generator. Thanks to all for the replies. And it's great to have Marty back.

Phil 

Marty, the only problem with a rotary switch is that on occasion one may want to have power on to all locos to let them charge, while running some of the locos.

To minimize cable lengths we used the relays  No need to bring the power to the control panel  You can use any switch you want to throw the relay  It can ve the cheapo's from Radio shack with no problem  We use Tyco relays

RJR, I do that.  I can reach each track and throw jumpers from center rail to center rail.  I do 5 at a time.  While that is going on, I turn on my ROW transformer and throw switches to direct power to the catenary and charge 5 of them.  At any charging week, I can charge 10 at a time that way.

 

I have a program on my workshop computer and record date when done.  I also have a very aggressive program to replace aging batteries.  I do not have one white battery on the system.

 

I have a very large number of sidings, yard tracks and turntable tracks and as stated before it is a must for me  to use the best switches to throw power on/off.

 

Ben is correct on using any cheap switch to throw his relays.  The DCS signal does not pass through the switch.  The contacts inside the relay do that job.  Ben also has some high end guys working on that layout and they know how much heat to put on one of those cheap switches.