Polar Express FlyerChief chuff questions

It is two cuffs per driver revolution

The chuff is generated by counting the tach pulses on the flywheel.

It is set by the firmware on the motherboard.

There is no tach on the LC (not plus).+

Here's a typical motor.

Both the AF Berk and PE locos have an optical tach wheel.

Look here and you will see it..

The LC+ has them, the LC doesn't.  At least for certain many or most of the plain LC locomotives don't have them.  I've had half a dozen LC O-gauge set engines apart, and I've never seen a tach in any of them.

As I said, they're not generating the chuff from the flywheel in those.   Go back and read my response, you're looking at LC+ stuff.

Carl's website has a video of his conversion of a 765 Berk to 4 chuff per revolution using the tender wheels in addition to other upgrades. Quite a nice upgrade.

Rich

Well Carl,

I don’t know what I’m looking for, however I am sure you know it is there.  Would you give me a hint?  Is there a possibility of adding 2 more pulses to the tach wheel?  That is, without doing heroics and converting to TMCC (or whatever it is).

Tom Stoltz

in Maine

No. It can't be done unless you know how to reprogram the firmware.

The chuffs are generated internally for the LC+ locomotives, there is no way to "add pulses".   It's conceivable you could "roll your own" tach sensor that had double the number of pulses/rev, it would result in the locomotive being half as fast, but having twice as many chuffs/rev.

All Flyer Chief locos use the Tach.  That is the topic of the this thread "FLYER Chief".

I know very little on American Flyer in general, but am at least trying to know as much as I can on LionChief/LionChief Plus.  As far as I have been able to discern, all FlyerChief engines share the same electronics package as their LionChief Plus counterparts.  There's no such thing as a non-plus version for FlyerChief.  This means that when it comes to modifying a flyerChief engine, all the same rules apply as when trying to do so to a LionChief Plus engine.  

GRJ's response seems the most reasonable here; Double the tach pulses on the motor to get twice as many chuffs with the drawback that the engine will move half as fast.  if something along the lines of 40-45 mph top speed is workable, it might be worth giving it a try. Depending on how the programing works, even this may not work.  It may cause a fault in the code if it is programed to know the given range for the PWM duty cycle at a given speed.  This is just a guess based on code I've used in other projects, however, and may not be an issue for LC+/FC engines.  

It appears in the locomotive pictured above that the sensor in question is a simple optical encoder, similar to what was used on a ball mouse... Not very much room there for adding slots.  Another option might be use electronics between the sensor and the control board to double the number of pulses.  Using discrete components I think this can be done with something like a 7474 flip-flop, but need to do my homework to remember exactly how, or if I'm even thinking of the right part.  For ease of use, I would probably just stuff a tiny micro-controller in there like an Arduino ProMini, and program it to output 2 pulses for every one it receives.  The micro controller route also allows for programing to output pulses that fall in the middle of the regular pulses with some creative code.  With either method one could install a switch to select normal(2 chuff, high top speed) or 4-chuff, half speed operation.  

With any method that effectively doubles the tach pulses it is worth noting that some of the low speed performance of the engine will be affected.  The first several speed steps will probably leave the motor stalled, so you will have to turn up the dial a bit more to get the engine moving.  

JGL

JohnGaltLine posted:

 

GRJ's response seems the most reasonable here; Double the tach pulses on the motor to get twice as many chuffs with the drawback that the engine will move half as fast.  

If you double the tach pulses and get half the speed, you will still only have 2 chuffs per driver revolution.  The only thing gained is a slower locomotive.

Rusty

Since the chuffs are obviously being triggered by the number of tach pulses Rusty, exactly how do you figure this won't work?  The electronics will think that the flywheel has made two revolutions instead of one.  This is Math 101 I would imagine.

Here's a pulse doubling circuit.  Frequency Doubler with 4011

I haven't analyzed if this could be driven directly from the encoder.

gunrunnerjohn posted:

Since the chuffs are obviously being triggered by the number of tach pulses Rusty, exactly how do you figure this won't work?  The electronics will think that the flywheel has made two revolutions instead of one.  This is Math 101 I would imagine.

Here's a pulse doubling circuit.  Frequency Doubler with 4011

I haven't analyzed if this could be driven directly from the encoder.

The statement was:

"If you double the tach pulses and get half the speed, you will still only have 2 chuffs per driver revolution."

Obviously, if you can double the pulses without a corresponding reduction in speed, you should get 4 chuffs per.

Rusty

Rusty, I have no idea what point you are trying to make.  If you double the tach pulses from the tach reader, no matter what your set speed, you'll get twice as many chuffs/rev of the drivers. 

Let's say you have a gear ration of 16:1, and 20 tach strips for each rev. (the actual numbers don't really matter for this discussion).  If I have two chuffs/rev, that means for each 16 rotations of the flywheel, I'll have two chuffs, or every 160 tach pulses.  One complete driver rev is 320 pulses.

If I double the pulses coming from the tach using a pulse doubler, I now get 640 pulses for each rev of the drivers.  Since the processor is generating chuffs each 160 pulses, I now get four chuffs/rev.  This is totally independent of speed.

I suggest you go for remedial math.