# Using a Pulse Generator Unit



## LGB333$$$$ (Oct 11, 2017)

Thought I'd see if anyone on this forum has any advice to the below question I've sent to the Phoenix Sound folks:

"I've installed a Massoth Pulsed Generator into an LGB Uintah locomotive originally to connect to a Massoth XLS Sound Decoder. But the Massoth decoder's chuff quality isn't good and I've complained to Massoth Germany that they need to improve their Uintah sound file........that was a couple months ago and no fix yet. So my customer instead now wants me to install a Phoenix P8 and Massoth XL Power Decoder. The Phoenix sound decoders only have a connection for a two lead chuff reed switch. Massoth's decoders documentation indicates the three lead pulsed generator connections as: Ground; Clock; and 6.5 volts. My question, can Phoenix sound decoders accommodate an input for a three lead pulse generator and, if yes, how?"

For those not familiar with a pulse generator, I've posted a photo of the unit that I installed into the LGB Uintah.

Tom


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## Dan Pierce (Jan 2, 2008)

Too late4 now, but I did the Zimo decoder with a fan driven smoke unit (charles Ro, Arisotcraft, and Trainli) and they run great. Zimo has a chuff that is created by the motor back EMF so no axle sensor is needed, however a sensor can be used and is simple to activate, just a single change to one CV.


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## krs (Feb 29, 2008)

Tom,
To throw some light on your question...
The old original way to control the chuffs was via a reed switch connected to an axle on the loco, that switch would close momentarily two or four times with each revolution and those momentary closures were used as the input to the sound module for the timing of the chuff.
The more modern method is to replace the reed switch with a Hall sensor which gets rid of the mechanical reed switch contact but requires power to operate, thus three leads are required, power, ground and the pulse output to the sound module.
Phoenix should be able to tell you if and how you could connect athe specific Phoenix sound module to a Hall sensor.
Maybe that is not possible and you have to go back to the "old-fashioned" reed relay approach as the sensor element.


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## LGB333$$$$ (Oct 11, 2017)

krs said:


> Tom,
> To throw some light on your question...
> The old original way to control the chuffs was via a reed switch connected to an axle on the loco, that switch would close momentarily two or four times with each revolution and those momentary closures were used as the input to the sound module for the timing of the chuff.
> The more modern method is to replace the reed switch with a Hall sensor which gets rid of the mechanical reed switch contact but requires power to operate, thus three leads are required, power, ground and the pulse output to the sound module.
> ...


Yes, I'm hoping Phoenix will say a Pulse Generator/Hall Sensor can be used, i.e., which connection can produce 5v. - 6.5v. for the power.........the other two connections should be the normal Ground and Chuff used for a reed switch.


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## krs (Feb 29, 2008)

LGB333$$$$ said:


> Yes, I'm hoping Phoenix will say a Pulse Generator/Hall Sensor can be used, i.e., which connection can produce 5v. - 6.5v. for the power.........the other two connections should be the normal Ground and Chuff used for a reed switch.



The P8 manual shows pin 7 of C2 providing +5 volts at up to 100ma for Hall Effect devices.


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## LGB333$$$$ (Oct 11, 2017)

krs said:


> The P8 manual shows pin 7 of C2 providing +5 volts at up to 100ma for Hall Effect devices.


Knut - Thanks for your response which matches what I received from Jim at Phoenix below. I need to do a test of a motor block with a Massoth Hall Sensor (or LGB factory-installed locomotive) installed and connect it to to a Phoenix PB17 or PB8 to see if it chuffs properly. I'm concerned that the Massoth documentation calls for the Hall Sensor to be powered by +6.5 volts, slightly more than the Phoenix's +5 volts.

"Is the hall sensor to be powered by the sound board or the decoder? If the decoder, you may only need to connect the Hall output (chuff) to the Phoenix Chuff trigger input. If the sound board is to power the hall sensor then the ground connects to Phoenix ground/trigger ground, the hall output to the phoenix chuff input and the hall +5V to the Phoenix +5V (Volume switch +5V connection is a good place to grab that)."
Jim
Jim Calahan
Phoenix Sound Systems, Inc.
3514 West Liberty Road
Ann Arbor MI 48103
United States


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