Optical Chuff Switch

John,

This looks really great.  It would give a more accurate chuff position/rate than putting them on the trailing truck.

If all my 2 chuff engines weren't already upgraded to 4 chuffs I'd give this a try. 

When the magnets fall off, you can consider this mod.

John,

it would be great, if you were publish a wiring diagram with parts.

There was an optical sensor at Dallee's. Can that be used ?

Thanks and regards

Albrecht

John, that is great. Can you supply me two of those preassembled to wire into my cruise cmander for my cab forward project??? I want to put them on the two tender trucks so I get some random chuffs from the two engines of the unit. Looks much more reliable than the reed switches.

Ron

Awesome idea John!

Albrecht, Digikey sells them. Here are the specs. Its an Optek OPB607A. You just need a current limiting resistor for the LED and note the polarity of the photo transistor.

http://optekinc.com/datasheets/OPB606-607.PDF

Pete

I love it.  Are you building kits to sell?  I'm getting a double chuff in reverse on my 3rdrail Hudson project.  No more dealing with reed switches.  Did I say I love it?

Pete is correct, it's the Optek OPB607A.  I had 5VDC available from the Super-Chuffer, so I just used a 270 ohm current limiting resistor for the emitter feed, and I also provided a 1K pullup resistor for the open collector of the Darlington output.  The output load was determined experimentally, I was initially letting the pull-ups in the Super-Chuffer and the TMCC board do it, but I was not getting reliable chuffs, it apparently needed a bit more current through the opto.  There was enough dark current through the opto to keep the voltage low.  There is another part, the Optek OPB606A that has a single transistor output and not the Darlington pair.  I have some of those as well, and I'm going to see if I can get enough drive out of them, maybe they'll end up being more suitable.

I ended up taking the spacing specifications with a grain of salt, when I tried to space them the .1 inches specified, it wasn't working at all, I was getting too much reflection from the wheel, even after blackening it.  I moved the emitter out to about 1/3", and then everything started working great.  I get about 4.5 volts black and around .8 volts when the reflective tape passes.  Fooling around with the sensor over various materials on the bench, I got similar results.  The spacing, at least for this application, has to be much greater than the spec sheet would suggest.  The bonus seems to be that it's not all that critical, anything from about 1/4" to 1/3" worked great.

Mounting these seems a bit less critical than reed switches with magnets.  This one is perched on a couple small pieces of fiberglass board to get it to the proper height to clear the frame recess and see the wheel.  I use CA adhesive to stick it there, it doesn't seem like it's going anywhere.  Getting the reed switch off the pilot truck took some effort, and I can tell you that Acetone is very lousy for actually debonding CA adhesive, contrary to what others might say.

I haven't thought about building kits yet, I just got the parts yesterday and worked on it to solve my problem with the job on the bench.  Now that I see that it works really well, I'll probably work to package it a bit neater. 

Ron, I like the idea of having two separate emitters on different engines to vary the timing, but there's one issue with most scale articulated locos.  There is only one motor driving both sets of drivers, so the timing won't really change.

John, I like these for their size, considerably smaller than the ones I had laying around though the ones I have, have small (~28-30 AWG??) leads embedded in them.

Tape must make for a great reflector but long term paint might be better.

Pete

Pete, that's aluminum tape, it'll last longer than paint.

I was thinking about folks oiling the axles and the oil creeping under the adhesive.

Pete

I'm sure white paint would work, it was just easier to put the reflective tape on.

The nice thing about this solution is it's easy to remove the tape, clean the wheel, and paint the stripes if you like.

John, I would put the optics on the TENDER wheels not the engines. ERGO, no auto sync.

Ron

???? Ron, The preferred spot is the drivers. Thats what you want the chuff to sync on. Tender or trailing truck wheels is just a bodge because its easier to mount magnets to. 

Pete

I'm not sure why you want them on the tender, you get exactly four chuffs when they're on the drivers.  What is the perceived advantage to putting them on the tender?

grj, neat solution; thanks for sharing it on the forum.

Carl, it was created out of necessity, it was looking like magnets were going to be a messy solution.  I've actually been thinking about this for some time, it just seemed like a good time to give it a go.  I am pleased with the result, so I suspect that I'll be doing more of them like this.  It seems less "fiddly" than the reed switch and magnets.  As long as you have 5VDC available, it's actually easier to do than the reed switch as well.

Nice job John and quick solid solution.

Great idea and post John.  Can this be done to any one or two chuff TMCC engines Lionel has produced?

Bob

It would work for any number of chuffs, that's triggered by the reflective segments on the wheel.  I'm replacing many original Lionel chuff switches with Super-Chuffer upgrades, this is the first of what I hope is many optical upgrades.

Wipe the chalk board clean-GRJ is at it again ! 

Oh please, not a clean slate.  Leave the stuff I already have working!

John, another elegant solution to a frustrating problem!

Thank you.

Great idea...

Do you think it would work on the K-Line A5 switcher ?

I was thinking about removing the mechanical switch and

put the optical one in there. Paint the axle black and try the tape ?

Or does the mounting on the underside of the engine seem to be

the best thing so far ?

No reason it won't work on any TMCC locomotive as long as you can find a place to mount it.  If the wheel flanges are visible from the inside of the shell, you can mount it there.  Many locomotives have to have it mounted under the frame to shine on the driver flanges.

The cam or axle would probably be too small to get the definition between light and dark, or at least That would be my thinking.

Interesting to see if it holds up under use.  The wheels can get dirty from grease, track gunk.

I am figuring out what I want to do on my Brass J.  There is plenty of access on the inside of the engine, this might be a nice method.  I also thought about the flywheel, but you would need some sort of divider circuit to account for the gear ration.  I wonder how hard that would be.  10 pulses in but 1 out.  G

I'm not anticipating any major issue with dirt, and if my metallic tape gets dirty, a wipe with a solvent rag will fix it.  If the wheels near the flanges are getting that dirty with grease, you need to change the lubrication intervals!   I looked at some stuff that has significant running time, and I don't think they're going to get so dirty on the inside as to cause an issue.

I originally thought about the flywheel, but the complexity of adding an adjustable counter for various locomotives made me decide to try this first.  Since these retrofits go into locomotives with varying gear ratios, you have to be able to tweak the counts.  If I had serial data capability for my Super-Chuffer, I'd probably have considered the flywheel and just divided the chuff input based on a configuration parameter.  That may be an option in the future, but it would take a new board design.

I hear you, but you should see some of the stuff I get to work on.  Gunk so thick on the wheels you scrape it off with a screw driver  G

My optical solution is not for those folks!

John, mounted on separate tender trucks the 4 chuffs on each wheel on the respective trucks would randomly run in and out of sync due to different wheel drags, minute changes in track curvature and so on. I think it would be quite effective.

So, my question is, can two of these optical sensors run off the supper chuffer or directly off the cruise commander????

Best Regards,

Ron H

Ron, on separate tender wheels, that would probably work. 

Now comes the interesting part:

Articulated sound boards already have the extra chuffing enabled, so adding these two totally random triggers would be interesting to say the least.   I have no idea how it would sound, it might make sense to select a non-articulated sound board for what you contemplate.  If you were generating roughly four chuffs for each tender trigger, that would get the count right.  One problem with multiple sources of triggers is when they get close to overlapping, it would cause sound boards to drop chuffs, there is a window where a double-tap won't trigger the sound twice.

Having just finished a few minutes ago adjusting a reed switch to minimize the double trigger I appreciate the problem. The Super Chuffer elegantly varies the on time of the fan motor with changes in chuff rate. I have used a one shot (monostable multivibrator) to shorten the on time and give distinct puffs up to higher speeds before it appears as a steady stream. While simpler, it doesn't change the on time of the fan at slower speeds like the Super Chuffer. Neither does it fix overlap. That requires sufficient distance between the magnets and reed switch so its closed for the minimum amount of time.

The optical solution makes it much easier to do this. 

Pete

Remember, the Super-Chuffer also runs the fan at low speed when you're stopped.

John,

I've selected the SP Daylight sound board. Two reasons: the chuff is closer to the AC12 in sound and two, it has both the whistle and horn sounds. The overlap double tap would not be a problem. Articulates sound a little spazzy anyhow now an then.

Thanks,

Ron

I'm be interested in seeing how this all works out.