# Heisler mechanical chuff trigger help



## East Broad Top (Dec 29, 2007)

Okay, I'm trying to install an old Sierra sound system into my Heisler. The mechanical chuff triggers in the cylinders are ineffective because they give me a chuff-chuff-pause-pause because they only make contact at the top of the stroke. (Am I missing something there?) I tried keying off of the driveline between the cylinders and the rear truck, but the rotational and translational slop makes consistent chuff detection next to impossible. I tried building a cam to put on the axle of the wheel, but that's proving to be a major headache also. I'd give up on the idea and go with voltage-controlled chuff, except the flippin' interface between the Sierra and my RCS doesn't support it. 

So, I'm looking for ideas to get a consistent, even chuff out of this loco. 


Later,


K


----------



## George Schreyer (Jan 16, 2009)

been there, done that. see link for a good solution 

I use very high energy magnets on the U joint just behind the engine so that the slight wobble of the joint doesn't cause a problem. 

http://www.girr.org/girr/tips/tips9/heisler_tips.html


----------



## Curmudgeon (Jan 11, 2008)

Tried that, too. 
There is 1/4 to almost 1/2 turn of gear and rivet "slop" in the drivelines. 
No matter what you do (and it can be minimized by removing all traces of cylinder contacts), you will get erratic chuffs. 

The only way to ensure consistent chuffs is on a driver, but they didn't give you enough room to do that. 

About the only engine I use auto-chuff on.


----------



## Cougar Rock Rail (Jan 2, 2008)

What are the motor blocks like inside? Is there room to press on a magnet wheel on the axle and put a reed switch pointing down into the motor block from the top? That's the way I ended up doing it on my LGB Heidi. 

P.S. I just looked at George's website and it looks like there is lots of room on the axle with the bevel gear. I would make up a magnet wheel using four magnets pressed into holes on the side, press it on the axle and send the reed switch in from the back of the truck so it is adjacent to the magnet wheel. You will have to watch the valve timing so the magnet wheel is turned to the right spot.

Something like this one:










Keith


----------



## George Schreyer (Jan 16, 2009)

hmm.. 

I get very steady chuffs... no complaints at all.


----------



## Curmudgeon (Jan 11, 2008)

And, it depends, George. 
Every one is slightly different. 
Some have a LOT more rotational play than others, some are "looser" than others. 
The square plunge joint is often loose enough to cause the u-joint proper to wobble with the shaft, keeping proper magetic lines of force to the reed switch a tad more difficult. 

Every one I have seen, with the slop in the shafts, it will "chuff-chuff-chuff....chuffchuff..chuff-chuff-chuffchuffchuff-chuff", etc. 
Of course that's at less than slot-train speeds. 

EDIT:

Oh, and one other thing.
Sometimes the magnet on the speaker (which is directly above that joint) can interfere with the reed switch.


----------



## George Schreyer (Jan 16, 2009)

hmmm... 

the slide joint on the one that I have is actually pretty tight, there is little wobble except at the extremes of the truck rotation and it still hits every time. 

My speaker is way to the rear nowhere near the reed switch which is under the firebox.


----------



## East Broad Top (Dec 29, 2007)

Well, after looking at a cam at Caboose Hobbies that would fit on the axle and give me 8 chuffs per revolution, I decided to save the $25 and try again with the magnets on the driveline, focusing on ways to eliminate the slop and extra motion. What I came up with seems to work. Essentially, I installed a foam block that pushes the driveline over towards the reed switch. This does two things. First, it keeps the driveline in a fairly consistent place so the distance between the magnet and the reed. Second, it introduces just enough drag on the driveline to where it rotates evenly. The only problem is that the magnets occasionally bump the casing of the reed switch, so in addition to the chuff chuff, I get knock knock. Maybe a spacer going the other way might take care of that, but for now, I'll live with it. I can't really hear it too much out in the garden. 

Later, 

K


----------



## SlateCreek (Jan 2, 2008)

I think a lot of this goes back to the "lopping" [sic] problem discussed at length when the locomotive first appeared. The driveline on many locomotives had some slop in it and when the piston was at TDC the spring tension in the chuff contact was enough to cause a snapping over of the piston rod and crank, in much the same way that George describes on his "how to stop the annoying tap-tap sound" page on the Shay. Particularly at slow speed, this caused a visible "lope" to the engine's valve motion. As we've experienced, different units have different properties on many Bachmann locomotives, but there were a lot of people who wrote in about it when the locomotive was new. 

I'm not as up to speed on Heislers as I should be; what's the ratio of chuffs to revolutions on a 1:1 Heisler? I know that can be a "trick question" because if I remember, some had selectable transmissions like some of the Climax locomotives did ... but the "usual" one will do here. If you were going to make a cam wheel on the axle as the fellow did above, how many triggers would you need to be accurate? 

Matthew (OV)


----------



## East Broad Top (Dec 29, 2007)

I don't know if the Heislers came in different gear ratios or not, but the Bachmann heisler is geared 2:1, which would translate to 8 chuffs per revolution of the wheel. By putting 4 magnets on the driveline universal, you get 4 chuffs per revolution of the cylinders, which is prototypic. In the garden, it might be too fast for most ears, unless you really make the Heisler crawl. Two magnets on the driveline results in a chuff rate that's a bit too slow for my ears, though. While not prototypic, I really think 6 chuffs per revolution of the wheels would allow the loco to run at a reasonable "garden" speed, and still sound good. 

Later, 

K


----------



## wigginsn (Jan 9, 2008)

Kevin, 

Any chance of some photos? 

I'm close to putting sound in my Heisler (saving up $$), and was looking at installing 4 magnets on the universal right next to the rear bogie. I figured the slop/movement would be the least obvious there. 

Be good to have a look at what you came up with. 

Cheers 
Neil


----------



## Stan Cedarleaf (Jan 2, 2008)

Kevin.... Just a bit of a different thought. 

I did an Airwire/P5 install in a Heilser for a friend and just left the chuff on voltage control. The chuff rate is adjustable and it works right nicely for him that way.


----------



## East Broad Top (Dec 29, 2007)

I didn't have the voltage control option because the opto-isolator I have between the RCS throttle output and the Sierra doesn't allow for it. (I think Dave said later versions of the circuit did, but this is from an old system that I'm reinstalling.) I tried to set it per the instructions, but to no avail. Essentially, the circuit I have tells the Sierra there either is voltage or there isn't, but no variation between though curiously I could adjust the start voltage, which caused my whistles to trigger after the wheels started turning. 

Neil, I'll try to shoot a photo for you tonight. Suffice to say function came primary to form, but it works. Since it's tucked up under the firebox, you can't see it. 

Later, 

K


----------



## George Schreyer (Jan 16, 2009)

The Sierra doesn't do voltage control very well with an optoisolator and ANY PWM source. 

It's complicated, but see my solution at 

http://www.girr.org/girr/tips/tips6/sierra_tips.html#dcc 

This circuit actually makes the diesel Sierra work properly. I've never used it on a steam Sierra, but I assume that it would work for the same reasons.


----------



## East Broad Top (Dec 29, 2007)

Boy, I'm glad that's such a simple circuit to build.  I think I'll be happy I got the chuff trigger to work. (Can you say "Phoenix" from this point forward?) 

Speaking of, however, is there a way to limit the volume going to the speaker *after* it leaves the Sierra board? I know I can adjust the volume on the Sierra board itself, but to bring it down to the level I find acceptable (which is pretty low), the baseline steam hiss cuts in and out. I'd like to move the volume on the Sierra board up to where I get all the sounds the right way, then limit them en route to the speaker. 

Of course, if its another simple solution like George's opto-isolator fix, I'll live with it.  

Later, 

K


----------



## TonyWalsham (Jan 2, 2008)

As far as I am aware, the RCS # SSI-12v5 opto isolator circuit gives a variable voltage for the Sierra sound so that the track inputs can control variable voltage chuff. 
The # SSI-12v5 also provides a regulated 12 volt supply to replace the SIERRA battery.


----------



## George Schreyer (Jan 16, 2009)

you can use a device called an L-pad to control the audio to a speaker. Basically, it's two wirewound pots. However, they usually are designed to handle MUCH more power than the Sierra can provide and are much too large. 

You can switch in a series resistor, maybe 10 ohms or so, to do the same thing in one step.


----------

