Need help with block signal relay build

Here's a relay I use for signals, it has a choke for DCS compatibility, and I used relays salvaged from old control system PCB's that were being discarded, read free.  They are 12V relays, around 30ma coil current.  You can power them from an accessory supply if desired by simply connecting the aux power to the Center Track connection in the diagram.  If you want more chatter protection for the relay, just increase the value of the capacitor.  The insulated track connects to the sense track, and the aux supply if used shares the common with the outside rail.

The following pic is from this thread:

https://ogrforum.com/t...32#49297155941256832

Your 7-light signal (presumably the PRR/Pennsy style) hooks up the same way as the 153 signal in the thread.  That is, you'd hook up the "proceed/vertical" wire as the "green" lamp, and the "stop/horizontal" wire as the "red" lamp.

The key feature of the relay module is the screw-terminals as soldering wires to relay-pins can be tedious.  Of course there are many relays that have mating sockets with screw-terminal connections...but you'll be hard pressed to find a relay+socket for under $2 (free shipping) as they are on eBay.  As the thread describes, you'll also need a diode, capacitor, and resistor.  If you are willing to deal with eBay Asia suppliers we're talking, say, 25 diodes/$1, 10 capacitors/$1, 50 resistors/$1, all with free shipping.  Since you're building several circuits, parts would net out to $2 or so per signal.  And you'll have a bunch of spare parts to share with friends!

If you prefer the convenience of your local Radio Shack, the equivalent parts would be, say, 5 times the cost.

Not to hijack this thread but I have a question for Stan.

Looking at the photo you just posted (which you also posted for me last week. Thanks again!)

Could the short orange wire and the + side of the capacitor simply have been inserted directly into the top terminal of the relay along with the diode? Meaning as a shortcut to soldering.

Thanks 

Mike

Thank you John and Stan for your replies. Lots of good info for the "electronically challenged".

I can't seem to locate any listings for the exact relay module in the picture. Would this board work as well  http://www.ebay.com/itm/12V-1-...b:g:9KEAAOSwrklVO4CD ?

That module would work fine.

Thanks John, parts are ordered!

graz posted:

Could the short orange wire and the + side of the capacitor simply have been inserted directly into the top terminal of the relay along with the diode? Meaning as a shortcut to soldering.

Thanks Stan!

John or Stan - I soldered up the components and connected everything to the relay module. The block signal works in the "straight ahead" position but when I connect the resistor leg (DC-) to the common, the relay doesn't change. I measured 12.5VAC input but only 1.7VDC between the DC+/DC- relay leads. I'm guessing there should be more DC volts there?

I'm using a 35V 220uf cap, 1N4003 diode, and 47k ohm 1/2 watt resistor. What did I do wrong?

rickoshay posted:

I'm using a 35V 220uf cap, 1N4003 diode, and 47k ohm 1/2 watt resistor. What did I do wrong?

Should be 47 ohms.  47k ohms is 47,000 [ohms...or 1000] times larger.

[Edited] per GRJ comment below.

rickoshay posted:

Thanks John, parts are ordered!

That was on Feb 3.  How did you get the parts so quickly?  

By any chance did you happen to order one of those resistor assortment kits where you get several hundred resistors of different common values for a penny or so a piece?

Well, it's really only 1,000 times larger Stan, but the effect is the same.

Thanks guys, after I posted it dawned on me. Newbie mistake! I'll order some 47 ohm units. I see some advertised as "5% carbon film". Does that make any difference?

John, I ordered parts from domestic suppliers.

5% or 1%, carbon film or metal comp, no difference in this application.

Upon re-reading I see you have a 12.5V AC accessory voltage.  Per GRJ's schematic, resistor R1 is chosen to match the relay current requirements.  The example I showed using 47 ohm for R1 had a 14V AC accessory voltage.  So when you get those 47 ohm resistor in, take two and put them in parallel.  This cuts the resistance in half (23.5 ohm) which should compensate for the lower available AC voltage.  Also, it looks like your relay module is of the 2 LED variety (one for power, one for when relay is on).  This adds to the current drawn by the relay module when active so the smaller resistance will help. 

If you haven't ordered replacement R's yet I still recommend a resistor assortment kit.

Stan - I'll try the two resistors in parallel. If all goes well with this project I'll take a look at some assortment kits although I doubt I'd know which one to use anyway.   I really appreciate you & John for taking the time to help walk me through this!

Success! Here's a photo of one of the relays that I made. I've included wiring details for the MTH 7-light signal for future reference. I installed two of the relays on the layout and they work perfectly. The two 47 ohm resistors in parallel did the trick. I've ordered several of the other type relays from Stan's earlier diagram. Should I also use parallel 47 ohm resistors with that relay? Still powering with 12.5 VAC. Thanks again!

Very neat assembly job! 

I tested the original (white colored board) relay module and it works fine with the single 47 ohms at 12.5V AC.

But since you have a working solution, why go back to the original example when the module you found is only $1.39 (free shipping)?  Example: eBay # 371514955180

Have them too.  Please check out there time delay  Relays.

Good luck,John.    

In fact, your tidy assembly job motivated me to confirm that you can DIY this using GRJ's design for $2 a relay if one is willing to use eBay Asia suppliers.  The resistor assortment has values for standard Accessory AC voltages or 18V AC command voltages if powering from the track.  Or if using bare relays instead of 12V relay modules, the assortment will have what's needed to manage differing relay coil current requirements.

eBay listings are constantly changing and I'm assuming this thread can be referenced in the future, so here's an example from early 2016:

Thanks for the great information Stan! I'll order one of the resistor kits just to have some on hand. Glad you liked my little relay board, it made for easy installation under the table.

NYCJohn, I considered maybe adding a timer (that's why the extra room on the board). However, I decided that since I run trains in both directions on my loops, I would make true blocks by installing a section of insulated track on either end of the block with each connected to the relay. My trains are generally long enough that the engine reaches the second section before the caboose is past the first, keeping the block signal activated until the train is clear.

Integrated Signals System.com and Shapeways.com

I'm going to try to finish up my block signal project tomorrow. Will my relay setup be robust enough to handle two of the MTH Pennsy signals? The signals are positioned at either end of a block and separated by about six feet (straight line). I have 24 gauge wire to connect the two signals to each other and to the relay but could also use 20 gauge if that would be better. Thanks.

The MTH Pennsy signals take very little current, they're all LED's.  Your wire is more than sufficient.

If you mean the 7-yellow LED Pennsy signals, then no problem.  I'd guess those draw about 0.1 Amps at most per signal head.  The relay on those eBay modules handles 10 Amps.  So you could run dozens of signals with one relay module.  24 gauge wire is more than adequate.

Kudos to John & Stan!! Everything is wired up and working. If I ever figure out how to operate my new video cam I'll try to post a video. Thanks for all of your help guys!

rickoshay posted:

Everything is wired up and working. If I ever figure out how to operate my new video cam I'll try to post a video.

Thanks for the report.

Too often there's a thread with a furious flurry of activity, then the trail goes cold and we never find out what happened. 

I have a related question.   I am using about 20 of the MTH block signals, some 30-11005 single head B&O style, some 30-11024 - 3 over 3 block signals and about 5 of the 30 - 11009 Cantilever signals...  These all seem to have a small delay circuit inside to go from Red to Yellow for <10 seconds,, then on to Green... 

Question: is it best to supply like 10VDC to the RED GRN signal lead wires, or will they accept 12VAC and do the DC conversion with the circuitry that's already built in ?  I can do either, but I am already bringing 12VAC accessory voltage to the relay and converting it to DC with a smoothing capacitor for the DPDT relay.   

chris a posted:

..I am already bringing 12VAC accessory voltage to the relay and converting it to DC with a smoothing capacitor for the DPDT relay.   

Are you using isolated-rail triggering and activating a 12V DC relay (DPDT) for each of your several dozen signal heads?

Yes, that's correct, one relay per signal head.  I have 10VDC buss running under the layout which I could use to power these signal heads, just would like to know if that's necessary or if the MTH scale signals already do that internally.  Read the directions, and of course they don't specify they just say hook it up to their ITAD device, which I don't plan on purchasing or using.   I already have my relays, caps, terminal strips etc.

To answer your specific question, yes the MTH signal head electronics which have the 10-sec yellow-to-green delay have AC-to-DC conversion built-in; the internal timing is performed by the venerable 555 IC timer chip which runs on DC.   An OGR member actually sketched out the circuit they use and became the basis for several threads on how to modify the circuit for customized signal heads.  I can scrounge for the info if you're interested. 

So if that closes the case, fine.  But if you are interested in discussing the matter further, if I understand what you have, I think you can simplify matters if you additionally power the relay coils themselves with power from a DC bus.  You say you are "bringing 12VAC accessory voltage to the relay" which suggests you have components at each relay to convert AC-to-DC.   You might consider performing this AC-to-DC conversion once (for all signals and relays) since you already have wiring to run a DC bus to all signal heads.

Let me also point out that the MTH Pennsy style signal with the 7 LED's does NOT like normal track voltages!  We cooked a bunch of them and now have a bag of dead signals.

If you have the exact circuit sketched out Stan, I'd like to see it.

Hey Stan,   I was planning to do the conversion at each relay, but I wouldn't mind looking at the schematic to do it "once" for all relay stations.  

My DC bus source is an old Lionel 0100 transformer, I happen to like it, but I was under the impression that you're not supposed to have any connection between the DC negative and the AC Common from my (4) phased ZW's.    I ran a 6 wire 16AWG cable around the entire layout to supply a choice of voltages.  The source for these are a couple of accessory "B" or "C" PW - ZW terminals...   So for the 6 wire bus, I have 10VDC + and -, then I have 12, 16, 20 and one "Variable"  VAC lines for running various switch machines, accessories etc.   I am running 4 different switch machines DZ1000, DZ2500, Atlas, and Tortoise, a total of close to 30 switches.  

I should also add that I am running Lionel TMCC & Legacy, but not running DCS, and for the moment I don't plan to add DCS.. 

gunrunnerjohn posted:

Let me also point out that the MTH Pennsy style signal with the 7 LED's does NOT like normal track voltages!  We cooked a bunch of them and now have a bag of dead signals.

If you have the exact circuit sketched out Stan, I'd like to see it.

I don't know about the 7-LED PRR style but this was posted by Fec_fan which applies to several MTH signal heads.  I'd think they would just "double-up" on the red, yellow, and green circuits for the PRR...and then just add an always-on 7th/center LED.  Hard to understand why it blows up with normal track voltage.

This also shows elaborates on Chris' question about AC-to-DC in the MTH signals assuming his are of this ilk.  There is one AC-to-DC diode for the red circuit, and a separate AC-to-DC diode for the yellow/green circuit.  So if choosing to run DC to the signal electronics, DC+ must be supplied to the red and green inputs, and DC- to the black common wire.

Thanks, now it makes sense.   The first few signals I hooked up, I supplied 10 VDC + through the relay to the RED NO - GREEN NC wire leads of the 11024 signal heads and ran the black directly to my 10VDC negative.  Everything worked fine.   It's been 10 year's since I had these signals out and operating on a layout and couldn't remember if the last time I ran them I supplied AC or DC voltage to illuminate the signal heads.   

So if I have both DC and AC available, do those of you who are EE's, and electronic experts, recommend powering the MTH signal heads with 10VDC ?  Is it likely to extend the life of the signal head, or it really doesn't matter ?  At this point I have run 100's of feet of wire and installed alot of barrier strips so it's not that much more effort to get DC +/- to the relay subpanel near each signal location. 

chris a posted:

Hey Stan,   I was planning to do the conversion at each relay, but I wouldn't mind looking at the schematic to do it "once" for all relay stations.  

My DC bus source is an old Lionel 0100 transformer, I happen to like it, but I was under the impression that you're not supposed to have any connection between the DC negative and the AC Common from my (4) phased ZW's.   

Here's an edited diagram from an earlier thread specific to my understanding of your situation.

This addresses the AC-to-DC conversion "once" concept...and using a DC bus.  It also suggests possibly simplified wiring by using a single DC bus to supply both the DC relay coil voltage and the signal head voltage.  The assumed MTH signal head wiring is as shown in the schematic from the previous post.  You can of course use the DC bus only for relay coil voltage and use AC to power the signal heads.

I'm not familiar with the Lionel 0100 but I see it was for HO so presumably has a adjustable DC output.  So it includes the functions in the blue box above.  Since it is a separate transformer from you main ZW transformers, it is electrically isolated.  So you can tie the DC- output to the outer-rail and use isolated-rail triggering.

There are i's to dot and t's to cross if this looks like something you want to pursue...such as the use of capacitors to demote relay chatter for intermittent wheel-track contacts.  

chris a posted:

So if I have both DC and AC available, do those of you who are EE's, and electronic experts, recommend powering the MTH signal heads with 10VDC ?  Is it likely to extend the life of the signal head, or it really doesn't matter ? 

The MTH schematic has a regulator IC chip (7812) which limits the internal DC voltage to 12V DC.  If you supply less than about 14V at the input, it will internally operate at something less than 12V.

So when you applied 10V DC, you get maybe 9.5V DC after the diode, and maybe 8V DC after the 7812 regulator.  So the 555 timer chip and yellow/green LEDs (thru resistors) are/were operating at, say, 8V DC. No problem though the LED brightness would be dimmer than if you supplied 11V, 12V, or more.  I wouldn't expect any material improvement in life-expectancy operating at 10V DC vs. 12V AC.

Stan, 

Thanks very much for all your input, it's most appreciated.  I know from reading many of the posts on this and related topics, you guys who know the answers must get tired of helping those of us with limited electronics knowledge.  

Yes my ZW's are phased, and all the "U" posts are tied together with 12 AWG stranded wire, and that 12 AWG common is routed to distribution blocks in key areas.   

I am really not drawing much current off the Lionel 0100 DC transformer.   Yes, it has variable output control, it's a brick like all the stuff they made back then.  At this point it's powering some LED's on my control panels showing switch position for some Atlas switch machines.    

Seems like connecting the Lionel 0100 DC Neg. to the AC Common would be the easiest solution ?  If that's so, would it be wise to tie some 220uf or 470uf caps across the contacts for the coils of the relays ?  And are there any other I's and T's I should address before I go any further....   And lastly, I suppose I should plan on raising the 10VDC to 12VDC, or will I see an increase if I tie the capacitor across the coils anyway. 

I have a bunch of 1N4003's and 1N4004's, alot of 470uf capacitors, and also a bunch of full wave bridge rectifiers that I have accumulated over the years getting ready for where I have finally gotten to....So if there's another way that you strongly recommend, I can solder, and put stuff together,  but I also like to keep it as simple as reasonably possible. 

Integrated Signals Systems .com. Should  you  like real Signals working on your Train Bard. 

And Shapeways.com Also for Signals.  

Good luck , John