Bachmann Online Forum

I have a Buchmann truetrack layout on the table. My problem(s) are:

1). I wish to add lights at all of my switches and at the control station. I have read a little about the Atlas Snap-Relay. I am having problems wiring this up, any help.

2). With the Buchmann trunouts, can the Atlas Snap-Relay work. How is this done.

3). On the Bachmann turnouts, the Atlas Snap-Relay says to wire in the frog. There is not one. Need help.

Is it Bachmann E-Z track or Atlas True Track?

For signaling switch positions, it does not matter whether you used Bachmann E-Z Track or Atlas True Track or somebody else's track as long as the turnouts use the normal dual solenoid, three wire switch machine control.  That lets out Kato turnouts, single wire and slow motion switch motors, air motors and mechanical linkages such as Bowden cables.

On the Snap Relay, there are three screws just like on a snap switch turnout motor.  Connect one wire from the turnout motor's left screw to the Snap Relay's left terminal, the middle screw to the middle screw and the right screw to the right screw.  If you are connecting to turnouts like the Bachmann ones that use a cable with a plug, split the cable into three separate wires at a convenient place.  Then connect a length of 3 wire cable, one wire to each of the switch machine cable wires.  I assume you know how to strip off the insulation, solder the joints, and tape them up.  Run your new 3 wire cable to wherever you want the Snap Relay, making sure that the middle wire in the original switch machine cable goes to the center screw of the Snap Relay.  The outside two wires can then be connected to the two outside screws, one to each.  I don't have my diagram that came with a Snap Relay sitting handy but if I remember correctly, they use a set of 3 screws to power the frog and yet another set of 3 screw to lighting signals.  You do not need to power the frog on a Bachmann turnout so you can skip that part of the diagram.

Unless you have already bought the Snap Relays, you might want to consider some of the alternate ways of connecting signals to Snap Switches and similar dual coil, 3 wire switch machines.  I am not sure if they are any cheaper but they sure are quieter which may be a consideration to you.

Jim 

Jim---
Thanks for your input on the snap track with lights. I am looking at putting a green and red light at each of my turnouts. I would like to also put a green and red light at the control table. I have the Bachmann black snap switches and the Atlas snap-relays. I am confused on the wiring. Is a there a simple wiring diagram on this. There are no frogs. I am stuck. Another question, when the switch is selected, does the light come on or is there a way to incorporate the lights to stay on the whole time the power is connected to the table. Please explain. I tried to read the paper that came from Atlas, I got so confussed.

I ran out of time tonight (getting ready to teach a class on building model railroads tomorrow.)  But I will try to draw and post a suitable diagram tomorrow.  Don't worry about your turnouts not having frog connections.  No frogs connections just means you do not have to wire them up.  I understand what you want and yes, by using the Atlas Snap Relays, the lights will stay on as long as the table is powered.  In fact, they next time it is powered up, the lights will come on showing the positions of all your track switches.  And they will be correct unless someone has thrown one of those switches by hand.  Atlas Snap Relays are special relays that throw one way or the other when you throw the associated track switch.  And just like your track switch stays one way or the other with the power off, so does the Snap Relay.

Snap Relays have other interesting uses too.  For example, if you want to control a slow motion switch machine such as a Tortoise from more than one place, you can use push buttons or other momentary electrical switches to throw a Snap Relay and have the Snap Relay control the Tortoise motor.  Because the Snap Relay requires only momentary power, you can power it from many push buttons if you need to operate it from many different places. 

I plan to install a couple of Snap Relays on my own layout when I have a bit of time.  I have a single track loop-to-loop layout and I want the two loop switches to throw automatically when a train approaches a loop switch from inside a loop.  I built an electronic circuit to do this but it did not work as reliably as I had hoped.  So I am replacing it with a much simpler circuit that needs only one Snap Relay and a couple of reed switches for each loop.  I used a similar reed switch circuit in another layout and it has thrown a pair of switches 400,000 times over the last 20 years or so without a single problem.  Very useful component that Snap Relay.

Jim

Jim-

A question. I haven't needed relays since I built a pinewood derby track for the Cub Scouts many moons ago and used them to show which car hit the finish line first. (The relevant Cub is now a mid-career NPS ranger so you know how many moons I'm talking about.) How do the prices of snap relays compare to simple low voltage electronic relays from an electronics house? Yes, I can research this myself but I thought I'd just see if you have the information at hand. You do seem to have a good bit of information at hand, by the by. Thanks.
                                                                                                                    -- D

Snap Relays in Canada run about $10 a pop while dual coil latching relays by Omron or Panasonic are about half that price.  Advantage of Snap Relays are their screw terminals for quick replacement, high current rating and easy availability from many hobby dealers.  Atlas does not publish such niceties as current ratings and expected life but I would guess something around 5 amps and 100,000 operations.  Advantage of the Omron or Panasonic latching relays are price and long life in dry circuits (ones where they switch very small currents.)  The price advantage starts disappearing if you have to mount them on a small Printed Circuit Boards (PCBs) along with a ten point terminal strips or plug them into sockets.  The Panasonic ones will plug into a common 16 pin DIP socket if you don't mind soldering to the socket pins but still want the possibility of quick replacement.  The Omron relays need a narrow 16 pin socket or two 8 pin socket strips and something to mount them on.  For switching low currents, e.g. 10 mA for signals, 50 mA for Tortoise machines and similar, either the Omron or the Panasonic should last about forever.  For power switching, such as loop control on DCC, their 2 amp non-inductive rating is rather limiting.

In wayles3's case, he already has the Snap Relays.  In my case using them for turnout control, I would have to replace the existing turnout motors with Tortoise or similar low current machines which would add to the cost of the Omron or Panasonic relays but could get away with adding just a couple of capacitors and resistors to the existing dual coil switch machines if I used Snap Relays.  I will have to give serious thought to upgrading to a Tortoise machine, at least at the loop which uses a stub switch.  Although it is presently thrown by an Atlas dual coil switch machine, its operation is marginal.  I believe the longer, stronger throw of the Tortoise would improve the reliability of this switch.

I don't always have the latest prices or specifications at hand but I do have a mouse at hand and it can quickly connect me to the internet.  I often use Digi-Key Canada because they show the latest stock and Canadian prices with all the duties and taxes built in.  I also like their catalogue with its ability to filter out the things I do NOT want which is a fast way of locating potential part numbers for what I DO want.  Thirdly, I appreciate their fixed price, overnight shipping for small parts which is about half the price of the "we will get it to you sometime" shipping via your post office and mine.

Jim

Jim-

Thank you. You confirmed what I expected and I appreciate your post.

                                                                 -- D

wayles3

I have a diagram for you but am having trouble uploading it.  I don't know if my ISP's ftp server is down or if Firefox, Norton and my ftp uploader are arguing over something.  I will keep trying.

Jim

Jim-
I can wait till you get the problem solved. If you can send it by regular email try it.
wayles3@live.com

Jim---
I received your plans on the switch lights, Thanks---
i tried to wire up one set of lights per the drawing. I had the same problem when I wired them up using the Atlas drawings. I matched all the wires by color and went from there.

The problem I am having:

When I power up the table, the a green light or red light comes on,the one I use for the control table lights, there is not enough juice to switch the track switch or the snap relay. I disconnected the snap relay and the switch works fine. I even used a separate power pack all on ac. Am I doing something wrong? I noticed the buss wire, I left all lamps with a white wire and tied them together on the buss wire, which goes to one of the terminals on the power pack(ac) and a red wire from the snap relay to the other terminal (ac). Please advise, thanks.

The above interchange may make more sense with the diagram.  It shows how to use an Atlas Snap Relay to show a steady indication of switch position when the turnout is fitted with a momentary dual coil switch machine.  While shown with light bulbs, it would work equally well with red and green LED's or three lead red/green bicolour LED's, using about a 1 k resistor  for each LED.  It can also be used with two lead bicolour LED's with a slight modification.  The two sets of bulbs or LED's allow one set to be placed near the turnout, possibly in the form of a searchlight type signal, and the other set to be on a control panel.  After a pleasant afternoon spent sorting out the problem between my ISP, my computer, Firefox and Fireftp, I finally discovered the latest update of Firefox did not want to play nice with the Fireftp add on.  But no new edition of Fireftp exists, so it was a matter of installing an older version of Seamonkey (Firefox's little sister) and adding Fireftp onto that.  ARRGH!!

(http://members.shaw.ca/sask.rail/Atlas-Snap-Relay-w.jpg)

---

wayles3
What I did not show in the diagram was a power pack operating the switch motor and the Snap Relay through the Bachmann turnout controller.  That power pack, which could be the same one that operates the lights, still has to be connected to the turnout controller as usual.  Thinking some more about that power pack, it would have to be strong enough to operate both a Bachmann turnout and a Snap Relay and to operate them both at the same time.  If I remember correctly, the Bachmann turnout takes about 1/2 amp and the Snap Relay takes close to an amp when they are running off 12 volts.  Theoretically, that would be 18 VA (Volt Amperes) which for practical purposes is about 18 Watts.  A power pack rated at 16 VA or 16 watts should be able to handle the two at once.  There is a bit of a fudge factor here - a 16 volt ac, 16 VA power pack can delivery 1 amp continuously.  When we ask it to deliver 1-1/2 amps, we are actually overloading it.  That will not harm it for short periods of time (a few seconds) but it will reduce the voltage, probably down to about 12 volts.  Check your power pack to see what its rating is.  If it is fairly new, the rating will be in VA.  If it is older, in will likely be in Watts.

In the meantime, I will check to see exactly what a Bachmann turnout draws and what a Snap Relay draws.

Jim

just a suggestion:

look into a capacitor discharge unit to power your switch motor and snap relay. that, added to your existing setup, should be enough to reliably throw both at the same time.

I thank you all for your input on the lights for my switches. Now--- is there a drawing with the same idea of putting LED's with the capacitors inline for this set up? If I am using incandescent bulbs before, will the power drain be less with the LED's? I am looking at other power packs or something to run---- 8 red lights, 8 green lights (2) at each switch and (2) at the control panel; enough power to run (4) Bachmann turnouts; (4) Atlas Snap-Relays; the track itself and all the lights I have in my buildings.   
***** The building lights are now run on (DC) one power pack only.
***** The track is on (DC) another power pack with my Atlas Switch controllers--no lights.
***** I have (2) more power packs, (1) for the switch lights; (1) for the snap-relay.
***** If I disconnect all of the switch lights and the snap relays the fist (2) power packs run everything.
I have tried to wire up (1) red & (1) green light on (1) switch and relay with (1) turnout, on (2) separate power packs,  the lights come on and the turnout barely moves; I hand switch the snap relay and the other light comes on.

Now if I have just the plain jane trains (1) powered locomotive, (1) unpowered locomotive, (1) caboose from Life Like Trains. Everything runs fine until I try to wire in my switch lights and relays.

Please advise.

I talked to tech. support with Atlas, they said that where I have (1) power pack operating the track and the switches; needs to be split up between (2) power packs. Too much juice being brawn off of this power pack. The power packs I do have are Bachmann. Atlas said that these are good for a single track around the Christmas Tree. I will go to my local Hobbytown USA and see what they have in stock. I will advise what I come up with.

I came up with some numbers for you.  The Bachmann turnout I tried drew .65 amps at 12 volts.  On the other hand, the Atlas Snap Relay drew 3.4 amps or as much as 5 Bachmann turnouts all being activated at once.

To see what some small train set power packs can produce from their ac accessory terminals, I measured the short circuit current of 4 of them.  This is the maximum current a supply can deliver and basically occurs when the output voltage is dropped to zero by the load.

supply                          rating            short circuit current

OLD Bachmann                 8 watts          2.1 Amps ac
trainset pack

Old Lionel                        6 VA              2.4 Amps ac
trainset pack

MRC Tech II                    13 VA              8.5 Amps ac

Bachmann                      18 VA ¹           .34 Amps ac²
44212 pack

notes:
¹ "wall wart" power pack rated 18 volts, 1 amp.
² this modern, electronic pack uses a PTC (Positive Temperature Coefficient thermistor) to provide foldback current limiting.  With foldback current limiting, an overload will cause the thermistor to heat up, reducing the current to a value below its maximum allowed level and will hold the reduced level until the overload is removed.  This is much quicker acting than the thermal circuit breakers used in the other power packs.  The response of the meter used in this testing was too slow to measure the maximum current produced before foldback and the value shown is the reduced level after the PTC current limiter kicked in.


The only one of these packs that would throw the Snap Relay reliably was the MRC Tech II which was able to put 3.7 amps through it while still maintaining its output at 13.5 volts.

Bottom line, the Atlas Snap Relay requires more current than small power packs can produce.

One solution is a larger power pack.

Another solution is a capacitor discharge machine as recommended by Jeffery.  A capacitor discharge machine is like a bucket that is slowly filled with water from a small pipe.  When you need a large gush of water, you the tip the bucket.  In a capacitor discharge machine, a small power pack fills a capacitor with electrons at a slow rate, that is, at a small current.  When you need a lot of electrons at once, that is, a large current, you dump the electrons out in a hurry.  Sounds very complicated but in its simplest form, you need only three electronic components in addition to a small power pack.  One is a bridge rectifier to change the ac from the power pack to dc.  The second is a resistor to limit the current going into a capacitor.  And the third is a capacitor to store the electricity until needed.  Typically, it takes 5 to 10 seconds to charge the capacitor but only 1/10 of a second to discharge it into the switch machine plus Snap Relay.  So the current coming out of the capacitor can be much higher than what goes in.  You do not get any more energy out than what you put in but the power (the energy per amount of time) can be much, much higher.  Cost wise, putting together a capacitor discharge machine is much cheaper than buying a large power pack.  And you only need one for all your switch machines/Snap Relays as long as you are willing to wait that 5 to 10 seconds between throwing switches.  If you are NOT willing to wait, there are somewhat more complex designs that reduce the wait to less than a second.  If this approach seems interesting to you, just let us know and Jeffery or I can walk you through it.

The third solution would be to use latching relays as recommended by Donaldon.  These can do exactly what the Snap Relays do but require only a small operating current to do it.  If you did not already have the Snap Relays, this would definitely be the way to go as the latching relays can be cheaper.  But with the relays already on hand, I believe the capacitor discharge machine would be the cheapest solution.

Jim

p.s. a drawing showing how to use LED's instead of light bulbs will be forth coming.

Good news---
I upgraded my snap track with lights, I bought (2) more power packs (17 va), took out all of the incandescent lamps replaced them with LED's with resistors, wired it all up, it works great, just what I wanted. 

Thanks for all of your support on this problem.

Good news!  Thanks for letting us all know.