Simple accessory-voltage flasher?

Could you work something up with an automobile directional flasher? The originals were bimetallic which don't play well with LEDs, new ones are solid state.

Yes, some I've seen have used actual automobile units, but most have suggested/required powering them with DC at or about 12 volts. I'm guessing that the old-style bi-metallic versions might work on AC, but at best it would flash only one on-off circuit, rather than the alternate-flashing effect I'm after.

Never mind -- I think I solved my own problem! It occurred to me that the Christmas light flasher bulbs I mentioned probably have a current capability similar to track-voltage incandescent bulbs, with a relatively low resistance. So, I just hooked one in series with such a bulb, and it worked -- well, for one bulb at least. Putting one in series with each bulb does produce a sort of syncopated alternate flashing:

I've attached an earlier 'breadboard' single light version.

There are about a dozen companies that make flasher circuits that give a very realistic alternating flash that you can use with Lionel and Marx crossing signals.  They run about 20 dollars but some have adjustable flash speed and cost a little more. You can use a train detection unit to turn the flash on and off as the train passes. I no longer use insulated track sections because of the sensitive electronics in the modern locomotives.

In addition to the off-the-shelf purpose-built flasher modules for model trains, there have been several OGR threads with a more DIY flavor with potential cost savings depending on your comfort level with soldering and/or component-level assembly.

This thread employs an automotive wig-wag flasher module.

This thread and this thread are but 2 OGR examples of a solid-state alternating flasher circuit with circuit boards designed by OGR members.

This thread describes a DIY method that uses eBay/Amazon modules sort-of Lego-style but does not require soldering or messing with tiny electronic components.

One consideration is whether the lamps are switched with a relay vs. solid-state transistors.  The "clicking" of a relay may or may not be objectionable.  And there's a potential issue of long-term reliability of an electro-mechanical relay vs. no-moving-parts transistors.

So there are indeed many "modern" alternatives.

Thanks, Stan, that's a helpful synopsis of the many ways our fellow hobbyists have solved the "flasher" dilemma, some of which I'd stumbled across in my preliminary research. What I was looking for ideally is something that might have been part of an around-the-tree layout "back in the day", using cheap components available last century. Like I said, I'm not adverse to more modern stuff (I've been using static grass and crossing guard sound modules/mini-speakers on my mostly-Marx layout, for instance!), but I was hoping for, and eventually figured out, an old-school kludge. Thanks again!

@Steve Tyler posted:

Never mind -- I think I solved my own problem! It occurred to me that the Christmas light flasher bulbs I mentioned probably have a current capability similar to track-voltage incandescent bulbs, with a relatively low resistance. So, I just hooked one in series with such a bulb, and it worked -- well, for one bulb at least. Putting one in series with each bulb does produce a sort of syncopated alternate flashing:

So your solution was a Christmas light "flasher" bulb in series with each crossing gate lamp?  That is, some times the bulbs will flash together in unison...and slowly drift to where they alternate...and then slowly drift to flashing together...etc.

@Steve Tyler posted:

...

However, I'm looking for an alternative means of generating a 'flashing' signal to a pair of lights. To my "old school electrics" brain, the simplest means would be to use a bi-metallic strip with contacts on both sides....

And to be clear, your research did NOT uncover an 'old school' method to alternate flashing with each bulb on 1/2 the time, wig-wag style (left-right-left-right...)?

Yep -- each light flashes independently, and since each flasher seems to have its own rate, the lights move into and out of phase, giving a somewhat syncopated effect, as I said. IMHO, this would be somewhat of an improvement over the flashing produced by the rail-top contacts traditionally used (though to be fair, Christmas light-string flashers do take a noticeable bit of time to warm up and start flashing). My hypothetical bi-metallic SPDT would give a true alternate-flash (though probably suffering the same warm-up delay), but so far, I've not found any such actual device, or any other alternative that doesn't involve a good bit of soldering, a number of components, a fair amount of money, or some combination of all three. I know, picky, picky . . . In any event, thanks again to you and everyone else who responded to, or at least thought about, my query.

@gunrunnerjohn posted:

In my opinion the origin of John's circuit would lie back in the early days, probably shortly after transistors were invented, because of it's absolute simplicity.  At some point transistors then became more widely available, and finally cheap enough to be affordable to hobbyists who would be interested in building this circuit.

I would suggest that this would place this basic circuit, although not with these specific transistors which came later, right smack in the middle of the postwar heyday in our hobby (late 50's at the latest).

If so this is a contemporaneous solution, and could just as easily have been put into production back then as a bimetallic electromechanical version could have been.

In the end I could attach one of my favorite terms to either or both, 'elegant simplicity', which today means no integrated circuits or microprocessors when not absolutely necessary.  KISS applies here.

Unfortunately neither appears to have been put into production for toy trains back then -- strange but apparently true.

Mike

Someone sent me that circuit a very long time ago, I happened to remember it was in my archives.

Fair points, Mike. Back in my ham radio days (early to late '60's, K3SKV), discrete transistors for hobbyist use were still relatively rare and pricey, and vacuum tubes still carried most of the electronic load (anyone else remember VTVMs and tube oscilloscopes?). John's circuit diagram jogged old memories, though since Radio Shack went out of business, I'd have no clue where to go for any of the components anymore. 🤔

Steve

For parts try local electronics supply dealers and eBay and other sites on line like digikey.com.

Charlie

For many years I had both a VTVM and several tube equipped 'scopes.  I used the Tek 545 'scope well into the transistor range, it was huge and bulky, but I had a number of plug-ins that made it a very flexible unit.  I bought it dead and brought it back to life.

Truthfully, back in those days, a 'scope like my Rigol DS1104Z-Plus with four channels, 16 channel logic analyzer, and arbitrary waveform generators was an impossible dream!  I was working in aerospace in the 1980's, and the 'scopes we had with lesser capability cost more than $10K!  Some things have actually gotten cheaper over the years.

@Steve Tyler posted:

I'd have no clue where to go for any of the components anymore. 🤔

Digikey or Mouser have way more stock than Radio Shack ever dreamed of.  If you fail there, one of my go-to sites is AliExpress.

Oh, sure, I know you can source just about anything online (if you're willing to accept the cost and delay of shipping), and I've always supposed some (reasonably) local supplier must have (at least partially) filled the void RS left, but it's just not the same as being able to drop by the local store (in my case, less than a mile from home!) at a moment's notice to pick up the odd resistor or capacitor. Yeah, yeah, "back in my day . . ." -- I'll hobble back to my rocker on the porch now . . . 🙄

Well, the costs for shipping of one resistor is pretty steep in comparison to the price of the part, I'll agree.   OTOH, I buy in bulk, so shipping is not a major part of the price.  I don't see any local places around me that have any assortment of electronic components, so it's either mail-order or nothing.

One way you can minimize the issue of going for "one" capacitor or resistor is to buy an assortment.  There are tons of resistor and capacitor assortments available for a few bucks, that gives you readily available parts in most common values.

I bought resistor assortments in 1/8W and 1/4W thru-hole sizes and also SMT resistors in 0603 and 0805 sizes.  Ditto for ceramic capacitors up to 1uf in thru-hole and SMT.  Finally, I have a large assortment of electrolytic caps.  I probably have less than $50 in all of those assortments, and for common parts, I have them right in hand.

https://www.amazon.com/AUKENIE...Caps%2C56&sr=8-4

https://www.amazon.com/AEDIKO-...&sr=8-8&th=1

https://www.amazon.com/HiLetgo...TG9nQ2xpY2s9dHJ1ZQ==

https://www.amazon.com/Capacit...Caps%2C39&sr=8-3