I would like to wire the loops in my 027 layout for blocks. I think I have an understanding of how to insulate the center and outer rails for this to work. I will be doing the recommended 3 blocks per loop to run two trains on each loop, so I will need three DPDT relays, 3 full wave bridge rectifiers, and 3 signals. I have the signals, but what specifications should I look for when I go to radio shack to buy the relays and bridge rectifiers? I found some that are DC. Will this work on my layout? I thought my layout is AC? (using a modern ZW) The relay I found is rated at 13.2VDC (continuous coil voltage), 9.6VDC pull-in voltage and the contact rating is 5A at 125VAC (resistive). Will this work? What do I need to look for in a full wave bridge rectifier? Perhaps part numbers at radio shack will be very helpful :)
Thanks!
Which relay should I purchase?
I found two relays:
The first one is rated at 13.2VDC (continuous coil voltage), 9.6VDC pull-in voltage and the contact rating is 5A at 125VAC (resistive).
The second one is rated at 14.4VDC (continuous coil voltage), 9.6VDC pull-in Voltage, and the contact rating is 15A at 125VAC
Both relays have equal coil resistance (160ohms), and equal nominal currents (75mA).
Does it matter which one I buy? What about full wave bridge rectifiers?
lionel2986 Which relay should I purchase? I found two relays: The first one is rated at 13.2VDC (continuous coil voltage), 9.6VDC pull-in voltage and the contact rating is 5A at 125VAC (resistive). The second one is rated at 14.4VDC (continuous coil voltage), 9.6VDC pull-in Voltage, and the contact rating is 15A at 125VAC Both relays have equal coil resistance (160ohms), and equal nominal currents (75mA). Does it matter which one I buy? What about full wave bridge rectifiers?
5A relay should be fine. the trains sholdn't draw over that. The relay doesn't draw alot of current so the FWBR does not have to be a high amperage rating. You can actuate a 12 volt relay with a 9volt battery. It will probably only draw about .07 amps at 12 volts. The FWBR is used to convert yiur ac transformer to DC to operate the coil on the relay
Will the second one that I originally posted work that is rated at 14.4VDC (continuous coil voltage), 9.6VDC pull-in Voltage, and the contact rating is 15A at 125VAC? I'm not sure if 15A is too high. Will the relay activate without 15A at a much lower voltage?
Will this work? (I am using a modern ZW with two 180watt bricks and up to 18VAC output)
http://www.ebay.com/itm/2-x-Power-Relay-Coil-12VDC-12V-DPDT-Contact-Rating-5A-240VAC-24VDC-/171119976060?pt=LH_DefaultDomain_0&hash=item27d78b9e7c
It's dirt cheap! But it says 240vac. Does that mean it will only work in Europe?
What about this one? it comes with a socket which is nice:
http://www.ebay.com/itm/DC12V-Coil-Power-Relay-10A-DPDT-LY2NJ-HH62P-HHC68A-2Z-With-Socket-Base-/121034195696?pt=LH_DefaultDomain_0&hash=item1c2e3342f0
Thanks
You're confusing the coil and the contact ratings. The coils of the relays you mentioned are rated to operate the relay at 12 volts DC. They don't say what the coil resistance or current is; but if you put 12 volts DC across the coil, the relay will operate and the coil will draw whatever current it is designed to draw, probably not much.
The 5-ampere rating for the first relay is the load current that the contacts can carry. The 240-volt AC and 24-volt DC ratings are for the open-circuit voltage of the load circuit that the contacts can stand to switch. Since your load circuit involves AC at a voltage much less than 240, the relay can handle it. The second relay is rated for a load current of 10 amperes, but no voltage is stated. However, it is very likely that its voltage ratings are similar to the first relay's.
Bob Nelson
Thank you for your reply! If you were me, would you purchase this:
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=310773680899&ssPageName=ADME:X:RTQ:US:1123
or this:
Are these good prices?
Does it matter and is there a benefit to any? I assume the different relays could be matched with any full wave bridge rectifier?
I would go with the heaviest contact rating, that is, the first one.
The outer rail is common to all blocks of your layout so there is no need to insulate it between blocks. Blocks are created by insulating the center rail . A SPDT relay is all you need to energize a block. DC relays are more common. If you use a bridge rectifier across the coil you can energize a DC relay with a ground pulse from an insulated track. If the relay chatters when pulsed use a capacitor.
As for relays, you should use a 10 amp relay in case there is a short and the train derails you would not want to fry the relay. I also recommend you install 7 amp circuit breakers to protect each block from shorts.
There are two outside rails, not one, and one of those two will have to be isolated to create the control rails to operate the relays. He hasn't said just how he intends to control the trains; but one way involves isolating one outside rail throughout each of the three blocks, to operate each of three relays that open an adjacent section of center rail in the previous block to halt any train that tries to enter an occupied block. In that case only one outside rail is common throughout the loop.
Presumably the second set of relay contacts are for operating the signals that he mentioned.
Hi,
I have done this for 2 seperate loops. Granted, I did not incorporate signals, but that should not matter. I will try and find some time tonight to take pics of the circuit I built and how I wired it. I think I still have my parts list with Radio Shack part numbers. The circuit I made has a "defeat" switch wired in so I could shut off the relay and just run one train with the flick of a switch. I will also try and post a youtube video of how the trains run on the circuit.
OK,
Here is a video of the schematic, actual circuit and the trains running on the block. Please ask if you have any questions. I would be happy to help.
https://www.youtube.com/watch?v=gsbCqzVXx8w
Mike
Lionelsoni - That is correct. I am using 3 rail track. Sorry that I did not clarify that.
I'm not sure than I understand Mike's arrangement of control and stop blocks, but I think it might be something like this: The control block precedes the stop block. Train A waits in the stop block until train B, approaching from the rear, enters the control block. This operates the relay, removing power from the loop generally and supplying power to the stop block. Train B therefore stops and train A starts up. As train A leaves the stop block, it supplies power momentarily to the layout generally, causing train B to start and move off the control block. As train B moves off the control block, the relay releases, restoring power to the layout generally and removing it from the stop block. Train A then proceeds around the loop while train B moves into the stop block and stops. Then the process repeats with the roles of the two trains swapped.
Perhaps this is not how Mike's design works; but the scheme that I just described seems to need some careful tuning of the block locations and the train lengths to work. For example, if train A doesn't bridge the gap long enough when leaving the stop block, both trains stop. And, if train B is too fast or too close to the rear of train A, it may rear-end it before it stops in the stop block. There are also considerations of what happens when either train has lighted cars with two pickups, that will bridge the gap after the locomotive has departed the stop block.
I think that the scheme that I described in an earlier post is more robust. It keeps any following train from entering an occupied block absolutely. The only restriction on the trains' makeup is that they be shorter than the shortest block; and that applies only if the number of blocks in the loop is only one more than the number of trains running on the loop. The penalties for this are the need to isolate a complete outside rail for each block and to use a relay for each block.
I have some comments about Mike's schematic diagram:
o The electrolytic-capacitor symbol shows the positive terminal (the straight line of the symbol) connected to the negative rectifier terminal. I doubt that his boards are actually wired that way, since his capacitors have not exploded!
o There are plus signs at several points at nodes that carry AC voltage--the center rails and the two non-common transformer voltages.
o It might be better to use a double-pole disabling switch, with the two poles connecting the transformer to both center-rail sections, so that the relay doesn't interrupt power twice for an instant each time a train goes through the control block.
lionelsoni I'm not sure than I understand Mike's arrangement of control and stop blocks, but I think it might be something like this: The control block precedes the stop block. Train A waits in the stop block until train B, approaching from the rear, enters the control block. This operates the relay, removing power from the loop generally and supplying power to the stop block. Train B therefore stops and train A starts up. As train A leaves the stop block, it supplies power momentarily to the layout generally, causing train B to start and move off the control block. As train B moves off the control block, the relay releases, restoring power to the layout generally and removing it from the stop block. Train A then proceeds around the loop while train B moves into the stop block and stops. Then the process repeats with the roles of the two trains swapped. Perhaps this is not how Mike's design works; but the scheme that I just described seems to need some careful tuning of the block locations and the train lengths to work. For example, if train A doesn't bridge the gap long enough when leaving the stop block, both trains stop. And, if train B is too fast or too close to the rear of train A, it may rear-end it before it stops in the stop block. There are also considerations of what happens when either train has lighted cars with two pickups, that will bridge the gap after the locomotive has departed the stop block. I think that the scheme that I described in an earlier post is more robust. It keeps any following train from entering an occupied block absolutely. The only restriction on the trains' makeup is that they be shorter than the shortest block; and that applies only if the number of blocks in the loop is only one more than the number of trains running on the loop. The penalties for this are the need to isolate a complete outside rail for each block and to use a relay for each block. I have some comments about Mike's schematic diagram: o The electrolytic-capacitor symbol shows the positive terminal (the straight line of the symbol) connected to the negative rectifier terminal. I doubt that his boards are actually wired that way, since his capacitors have not exploded! o There are plus signs at several points at nodes that carry AC voltage--the center rails and the two non-common transformer voltages. o It might be better to use a double-pole disabling switch, with the two poles connecting the transformer to both center-rail sections, so that the relay doesn't interrupt power twice for an instant each time a train goes through the control block.
I am trying to remember exactly how my circuit works. lol. I think I built it about 4 years ago. All the defeat swx does is bypass the relay so that the stop block is energized when throttle is applied. OK, let me try and clarify some of the questions. It will help me remember also.
1. The reason for the + connection on the control block is to provide power to the stop block when the defeat swx is activated. It has nothing to do with the automatic block portion. You could eliminate the defeat swx and the + from the control block to the relay and the block would still function. You just would not be able to defeat it.
2. The train hitting the control block always has power and will never stop. The control block is the trigger to release the stop block.
3. I will check my board and see how I wired the cap. I am usually very careful when drawing a schematic and check it many times. It would appear the symbol is reversed.
4. When I get a moment I will redraw the circuit (after verifying cap) without the defeat swx and maybe it will be a little easier to understand what I did.
5. Yes, there is some timing involved and testing block locations. My loops are small enough that I can get away with this simple setup. I would think with a larger layout or trains with vastly different speeds you would want to do something like Bob has suggested.
OK. I re-drew the schematic without the defeat swx. Here is the link to the new video. I included all the Radio Shack part numbers also.
https://www.youtube.com/watch?v=afQ-p_9Die8
Thanks for the explanation, Mike. I thought you must be switching power to the center rail outside the stop block, because it is not necessary to have that connection in order to disable the circuit. All you need is to wire the disable switch in parallel with the normally-open relay contact, to simulate the relay's always being operated. No connection is needed to the normally-closed contact.
My comment about the plus signs still stands. Plus and minus signs are appropriate for DC circuits; but AC voltage, while instantaneously positive or negative, is on the average zero, neither positive nor negative.
Now that I see how your loop works, I realize that it is almost the same scheme that I used in a previous house for an around-the-walls loop above my layout. However, I didn't use any relays, or electronics at all. Instead of switching the center rail of the stop block on and off, I switched both outside rails (together). So I was able to connect the stop-block outside rails directly to the control rail. I also had a signal at the end of the stop block, with the red lamp between the outside rails and common to show red when the outside rails were disconnected, and the green lamp between the outside rails and the center rail to show green when the outside rails were connected to common by the control rail, again with no electronics except for an extra hidden lamp in parallel with the green, so that only the red would appear lit when the control and stop blocks were unoccupied.
I see now that I would not need the connection from the control block center rail to the relay. The swx would just jumper the relay.
That is also a good way to run two trains without any electronics. It was fun designing, building and implementing the circuit though. :)
So I just looked at my circuit board and found that I did not wire the +center rail on the control block on either of my loops. I must have realized I did not need the connection, but never scratched it off the schematic.
I just wanted to let you know that I do not run any modern trains on my layout, so I cannot speak to the effects of the circuit on modern locomotives. Everything I run is postwar. Yes, I believe I installed the capacitor to stop the relay chatter. I have had two of these in place on two different loops for at least 2 or 3 years and I have had no problems whatsoever.
The defeat swx is nice. For example, my Uncle and I set up a 4x8 layout every year at his house and I bring up whatever Lionel trains he wants. He received some of our Lionel trains as a child. I always take the Sante Fe passenger train and that is one of two trains I run on my outside loop. Now all I have to do is flip the swx on the circuit and the other train does not get stopped by the block and runs continuously.
Hope this helps or clarifies things.
Merry Christmas!!
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