# Chuff Cam



## Dwight Ennis (Jan 2, 2008)

This isn't exactly a large scale question, though I think it probably also applies. I have a Bachmann On30 loco with a Micro-Tsunami decoder, and I'm not a big fan of electronic chuff synchronization. Consequently, I've installed a chuff cam from Tony's Trains on one driver. Does it matter which side of the loco that driver is on - i.e. engineer's or fireman's side? On this particular locomotive, both drivers are insulated from the axle and power is picked up by wipers on each wheel. My concern is whether or not it matters to the chuff circuit which rail the signal comes from.

Thanks.


----------



## Semper Vaporo (Jan 2, 2008)

Not sure I understand your question (The subject line conjured up images of a video camera looking down the stack!), but does this help: 

Assuming a standard 2 cylinder, non-compound locomotive... There should be 4 equally spaced chuffs per 360 degree revolution of the drivers... generally the chuffs should occur when the drive pin is at about 2:30, 5:30, 8:30, and 11:30 o'clock when going slow and earlier when going fast... (2:30 and 8:30 are chuffs from the cylinder you can see and the other two are from the other side... makes no difference which side you are looking at!) 

But who can "see" the position of the wheels when the loco is moving down the line to know if the chuffs are occuring at the correct rotational place... it is hard enough to count chuffs per revolution. 

A 2 cylinder, compound will have just 2 chuffs per revolution. The position of the wheels when the chuffs occur now depend on which side has the low pressure cylinder. 

A 3 cylinder will have either 6 or 2, depending on whether it is non-compound or compound and the timeing is by thirds instead of quarters.


----------



## Ironton (Jan 2, 2008)

Dwight,

Is this cam mechanical or electrical. Mechanical the answer is the sound decoder could care less. Since the interruptions are caused by a switch the wiring is the same both ways.



If electrical, is it magnetic or done by wipers or an electric eye. If magnetic see above. (All mine are magnetic). If by electric eye, see above.


So that just leaves wipers. I do not know, probably not. I would try it, but then again I tend to just go ahead and do things.


I know, more information than you wanted.


----------



## Dwight Ennis (Jan 2, 2008)

Is this cam mechanical or electrical.
Soundtraxx calls them "Cams" but in reality they are a small PC board with radial traces (4 at 90* for conventional rod locos, more for compound and geared locos) that one glues to the inside of the driver and connects to the axle (or in this case, the tire) via solder or conductive paint. Contact is made by a wiper connecting to the chuff input of the sound decoder and contacting these traces as the driver revolves. 










Mechanical the answer is the sound decoder could care less.
That answers my question. Thank you.


----------



## bobgrosh (Jan 2, 2008)

If on DCC that cam will work with a Tsunami. 
If on DC that can will work in only one direction. The direction will depend on which side you put the cam on. 
Check the Tsunami manuals for a solution, seems I remeber something about a bridge rectifier.


----------



## Dwight Ennis (Jan 2, 2008)

Thanks Bob. I'm using DCC - a Progidy Wireless system. 

BTW, forgive my ignorance (I'm new to DCC), but is AC on the rails with DCC?


----------



## Greg Elmassian (Jan 3, 2008)

Yes, depending on what you define as AC. 
The voltage and current does indeed alternate on DCC. 

It is a square wave as opposed to a sinusoidal wave from your household outlets. 

The width of the pulses/waves (if you will) is modulated and this is where the "data" is. 

Regards, Greg


----------



## Semper Vaporo (Jan 2, 2008)

But is it "Alternating Current", or is it pulsed "Direct current". AC implies that the current flow reverses direction for at least part of the wave.


----------



## Greg Elmassian (Jan 3, 2008)

It is Alternating, it does reverse polarity, as opposed to pulsed DC which is only one polarity, from zero to one extreme. 

Regards, Greg


----------



## Dwight Ennis (Jan 2, 2008)

Thanks for the info Gents. I have a couple of books on order that covers this stuff.


----------



## Greg Elmassian (Jan 3, 2008)

Call me some time Diwght and let's shoot the breeze on this.... I'm a DCC junkie... ha ha... 

Greg


----------



## Dwight Ennis (Jan 2, 2008)

Call me some time Diwght and let's shoot the breeze on this
Email or PM me your phone number Greg.  Sounds good.


----------

