No doubt a triac can fit in a smaller space than a relay...but for the 2 (or is it 3 
) guys that run O-gauge on DC track power the DC-relay method is arguably a more "universal" solution. Additionally, I'd think there might be some considerations running a garden-variety triac on high-frequency DCC for the handful of guys in that neck of the woods.
I don't recall how much current the relays here have to switch, but rather than replacing them with triacs, you could use a pair of FETs to allow AC/DC operation. It can also be done with a combination of diodes and NPN/PNP transistors.
JGL
At the price of Chinese relays, and the simplicity, I'm not about to go the triac route. Do triacs have any problems breaking a heavily indictive load?
Or, faced with the spectre of assembling a multi-transistor circuit, one could just buy a Solid-State AC/DC Relay which is just that. IIRC his under $1 relay handles 16 Amps which is above and beyond the call of duty! If space is an issue, there obviously are more compact 12V DC relays suitable for the lower Amps in an actual operating car.
There is something comforting about hearing that relay "click" to know that All's well in Mudville. 
RJR posted:At the price of Chinese relays, and the simplicity, I'm not about to go the triac route. Do triacs have any problems breaking a heavily indictive load?
If you are satisfied with the circuit as you have it, I wouldn't change a thing!
SOME of us (like me) enjoy the science project aspect of the hobby as much as the operating and building. Don't let us distract you!
RJR posted:At the price of Chinese relays, and the simplicity, I'm not about to go the triac route. Do triacs have any problems breaking a heavily indictive load?
You are on the right track. For the matter at hand, change the word "any" to "many"! PLCProf said he's messing around and for a one-off this would be a fine candidate to experiment with triacs.
However if this were for a manufactured volume application a designer would probably select a solid-state switch matched to the load which would undoubtedly save space, cost, power, etc. relative to a general purpose relay.
With the current circuit, I'm as happy as a skunk in a cabbage path. I don't like to be cutting edge. I agree a volume maker would do things differently, but I run out each unit by hand and there are occasional glitches. (Very hard to see a single strand of a #28 wire
) I also had bought a dozen of these Zettler relays because the price was so cheap, and this has given me a use. What's IIRC?
Prof, you're right. Trains haven't been running while I've been tinkering on this project.
IIRC = If I Recall Correctly.
And it is hard to see a strand of #28! Stranded #28 is really, say, 7x36... so yes it is hard to see #36!
And when it touches an adjoining component on a perforated board, it has an effect.
Where can be found the relay to which you refer?
If you mean the solid-state relay, take a look at Jameco. Whether these are cost effective is another matter but this was sort of responding to JGL's comments about cobbling together a combination of transistors and related components to switch DC and/or AC voltages. A SSR is just that...a combination of transistors and related components conveniently packaged together to essentially behave like a relay - two contacts to trigger it like the DC coil voltage of an electro-mechanical relay, and two contacts that get closed/switched when triggered like COM and N.O. of an SPST electro-mechanical relay..
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Thanks. Not cost effective. These units are costing under $2 each. Big expense is roller pickup trucks. I exhausted my stash and had to buy 4 481-10 conversion couplers. That added $10 each to 4 of the cars.
By way of update, I have finished all of my operting cars save 2, and am wll pleased. I'll post pictures. The 2 I haven't finished are:
1. An MTH ore dump car. It took me awhile to get MTH roller trucks with ground wipers, and even now I casn only get them with long couplers. The current slide shoes jam in switches so it is unusable.
2. A pre-war Lionel log dump car, which is very small and has almost no space.
I finally bought a bunch of the ground axle wipers so I could add rollers to trucks.
GRJ, only MTH trucks with rollers that I could find have long bars supporting the couplers, to extend them under caboose platforms and passenger car vestibules. Have you found anything else? MTH dump car is almost ready for testing--a few more connections to solder
RJR posted:GRJ, only MTH trucks with rollers that I could find have long bars supporting the couplers, to extend them under caboose platforms and passenger car vestibules. Have you found anything else? MTH dump car is almost ready for testing--a few more connections to solder
I make my own. Plain MTH truck on the left, two parts in the middle, fully assembled collector truck with axle wiper on the right. Not shown is the little screw to attach the axle wiper.
Many MTH trucks have the little "fork" on the rear to attach the pickup roller.
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GRJ, do you happen to know the part number (if one exists) of the harness that includes the ring (A) and press-fit (B) terminal contacts that he would need to make his own?
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I don't off-hand, but the slide-on looks to be the same as the Fastrack one. Personally, I solder the pickup wire on. I have a bag of small ring terminals, and I just solder up my own for those as well, never tried to buy a harness. You can also simply solder to the axle wiper near the screw.
Your picture looks like someone home-rolled that pickup holder, at least I see perfboard peeking out. 
I used a wire and ring left over from ps2 upgrade kits. I soldered wire to roller tab. I haven't been able to locally find ring terminals that small.
Truthfully, I don't go looking locally for stuff like the ring terminals, I just buy them on-line.
These are the ones I'm currently using: http://www.digikey.com/product.../298-10067-ND/450223
GRJ, but your in the train repair and electronics business, and have need to regularly order stuff. I am not, and have no interest in subsidizing UPS, FEx, or USPS unnecessarily.
Well, when you think about it, by the time you drive around to a few stores searching for an item like this, you've subsidized the oil and car companies, but it still costs you. I won't even get into the time driving around and not finding what you want, I can do a search on the Internet and find most things is a few minutes.
But to make this conversation useful to a broader audience, I think an itemized parts list of what it takes to "make" a powered rolling-stock truck from a generic truck is in order. Or maybe it's just cheaper to cannibalize a pair of powered-trucks from whatever the least expensive piece of rolling stock?
Given one-time shipping cost, I think that harness with the ring terminal and press-fit connector would be a useful item to simply purchase from MTH (if it's offered) along with the aforementioned items. I entered the number for the axle wiper (11-0000006) but no luck on the MTH Parts page. The roller (BD-0000092) appears valid - Pickup (8.0x10.7mm roller) - $5. So many of the items have "No Image Available".
RJR posted:2. A pre-war Lionel log dump car, which is very small and has almost no space.
Is this a statement of a problem looking for a solution? I noticed in another thread that GRJ posted dimensions of an incredibly small 5-Amp relay; I figure the relay is the largest component you need to cram into your operating cars.
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stan2004 posted:But to make this conversation useful to a broader audience, I think an itemized parts list of what it takes to "make" a powered rolling-stock truck from a generic truck is in order. Or maybe it's just cheaper to cannibalize a pair of powered-trucks from whatever the least expensive piece of rolling stock?
Given one-time shipping cost, I think that harness with the ring terminal and press-fit connector would be a useful item to simply purchase from MTH (if it's offered) along with the aforementioned items. I entered the number for the axle wiper (11-0000006) but no luck on the MTH Parts page. The roller (BD-0000092) appears valid - Pickup (8.0x10.7mm roller) - $5. So many of the items have "No Image Available".
I just purchased the wipers from MTH parts, so I know they exist.
| 616885 | II-0000006 | Ground Strap |
The order was dated 5/26/16, and I received it the first week in June, I got 30 of them. The number is II-0000006, not 11.
BTW Stan, I think there is actually a "slimline" version of that relay that's a bit smaller, I have never purchased it.
Well then. $5 for roller, 15 cents for ground strap.
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Stan, I "think" that the first two digits of the MTH part numbers are always alpha.
GRJ, do you have a number (Digikey?) for the relay Stan mentions?
They're the AXICOM IM series relays: Digikey AXICOM IM Series Relays, they come in thru-hole and SMT versions.
If your looking for really cheap Relays and led's.
Please go to Bang Good.com
Good luck, John
gunrunnerjohn posted:They're the AXICOM IM series relays: Digikey AXICOM IM Series Relays, they come in thru-hole and SMT versions.
That DK link goes to "Up to 2 Amp, signal relays" relays. Are you extrapolating contact derating at lower operating voltage (e.g., 20V AC O-gauge) for 5 Amp operation?
I fussed around a bit on DK and I think this gets to the 5 Amp (250VAC) version of that IM series relay:
Thanks, GRJ. I see in the 5mp version, they're DPDT despite the small case. SUrprising that they can squeeze 2 sets of contacts in.
Yes, I forgot to mention there is a 5A version. They're great little relays, I've used them for a number of things. One application was my little locomotive motion sensor. I use this to trigger stuff like Rule-17 lighting, cab light control, two-level smoke volume control, MARS lights only in motion, etc.
I can assure you that you won't find similar relays at www.banggood.com You can also find all the stuff I see there on eBay for less money, and it's doubtless coming from the same Far East source.
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GRJ, what's that gizmo you just pictured?
Stan, yes I am seeking ideas. I'm attaching some photos: One shows the 1941 log dumper with bottom cover off. Another shows the pre-war and postwar log cars for comparison--note the differences in mechanism, length, and space. Another shows the original trucks and the stock MTH roller pickup truck--note coupler mounts on a bar. Another shows a modern MTH ore dump car with the new installation almost complete. Relay just squeezes in--it's somewhat smaller than the others I've used.
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2 more pix: prewar log car with bottom cover on. Another shot of modern ore dump car.
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If the pre-war car can be operated without the bottom cover, it appears the relay could fit to one side and the electronics to the other side of the mechanism. If you need to operate WITH the bottom cover, maybe nibble off the middle portion of each slanted side. If you don't want to carve up the original metal cover, maybe fabricate your own bottom cover using bendable tin sheet with modified slanted wings, solder any seams as needed, paint black for looks.
RJR posted:
Is the "short" coupler truck still an issue? The trucks that GRJ and I show in our most recent truck photos are the "short" coupler style with roller and axle connections - in other words buy or make your own. For example, on the right "short" coupler truck in your photo above it seems the sliding shoe and metal box under it should pop off so that adding the $5 MTH roller part and 15-cent axle wiper makes it into what you show on the left "long" coupler truck. Or maybe I'm misunderstanding the "short" coupler issue.
RJR posted:GRJ, what's that gizmo you just pictured?
That's my Engine Motion Detection and Triggering Circuit that I posted about a few years back. Stan should recognize it, he suggested a key improvement that made it work much better. I didn't think I'd get enough takers to make it into an official product, but I use them whenever I need that capability.
stan2004 posted:Is the "short" coupler truck still an issue? The trucks that GRJ and I show in our most recent truck photos are the "short" coupler style with roller and axle connections - in other words buy or make your own. For example, on the right "short" coupler truck in your photo above it seems the sliding shoe and metal box under it should pop off so that adding the $5 MTH roller part and 15-cent axle wiper makes it into what you show on the left "long" coupler truck. Or maybe I'm misunderstanding the "short" coupler issue.
I hope I didn't do an ad-hoc conversion for nothing, I assumed that's what he needed, that's why I put that one together.
gunrunnerjohn posted:That's my Engine Motion Detection and Triggering Circuit that I posted about a few years back. Stan should recognize it, he suggested a key improvement that made it work much better.
Hmm, I do recognize it but had forgotten about it! What's ironic is RJR's circuit is a subset of your circuit. What goes around comes around! 
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What's ironic is RJR's circuit is a subset of your circuit.
Huh?
Stan, what you say about clipping off shoes is correct, but I just hate to destroy items that maybe, just barely maybe, I might need in the future.
Since there are prototype rail cars with long couplers, I'm not bothered enough to tackle a conversion.
RJR posted:What's ironic is RJR's circuit is a subset of your circuit.
Huh?
This has no consequence other than I find it mildly amusing. In the following messy drawing, each component in your circuit exists in GRJ's circuit and with identical interconnections. In other words you could use his bare circuit board and populate it with your components. The values of the components change but the function/purpose of each component is the same in both circuits. Part of the irony is that his trigger is an optical-coupler chip (which consists of an LED and phototransistor). Your trigger is essentially the same except the LED is on the track and the phototransistor is in the car!
Ah ha. So I went to look at a sliding shoe truck; I mistakenly thought the box/housing holding the spring-loaded sliding-shoe popped out. So extra hassle to grind/destroy it. Funny thing about the trucks; I guess it all depends on volume but I didn't think they'd tool a separate casting for the sliding-shoe version. In fact I found one that doesn't even have the threaded hole for the ground-strap!
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