[HOsteam] Questions/answers


Chris Shinn <cnshinn@...>
 

Hmmm...

Ok, let's try this. I don't know if I could be right, but
I'll put in my 2 cents. What type of power are you
running at home where this problem doesn't appear?

I'm thinking it may be lower, both in voltage & amperage
then what is powering the Aristocrafts. Could your wiper/
ground be shorting some how at the club?

What I'm thinking here is based on my seeing "arcing"
from my DCC system. Because of the constant
voltage of DCC, and the higher amperage, it's easy to
get a momentary spark from the back of a driver wheel
if it touches a turnout point, or at the frog of a Peco
Insulfrog turnout (where the two rails come to the point
of the frog and are isolated from each other by a sliver
of plastic). I've got some older Mantua & Rivarossi with
pre-RP25 wheel profiles that reach beyond the insulator
on the frog and momentarily touch the other rail.

Could it be the club is using a fairly high amperage power
source (4 - 5 amps), and your wiper is creating an arc to
the loco chassis? I've seen wierder things happen.

Just a thought...

Chris Shinn

----- Original Message -----
From: "Tom Knowles" <ncstl@mindspring.com>
To: <HOsteam@egroups.com>
Sent: Saturday, September 02, 2000 7:29 PM
Subject: Re: [HOsteam] Questions/answers


Chris, thank you for your ideas...
you may be right about the club's power being pulse, or at least pulse
modulated. The sound is louder at club, too, so that may be part of the
answer. Actually the sound system is nothing more than a white noise
genrator and audio amplifier pair of IC's on a board with a few
appropriate
resistors to set levels. Not a commercial unit, and there is no provision
for lights on it. The power is picked up through the rails via a diode
bridge and filter cap. Everything fits on a 24 pin IC socket and is in the
tender, including the 8 Ohm 1" dia. speaker. The ground is picked up from
the side of one of the loco's drivers with a wiper. The driver has four
thin
crescent shapes of epoxy that interrupt the ground and just turn the
circuit
on and off. The effect is stunning. Perhaps this is the wrong way to go
about it, I should leave the circuit on and switch the amplifier's input?
That would greatly complicate the switching and wireing arrangement at the
engine which at this point is only one wire and a little circuit board
screwed to the bottom of the frame. It has two hair-springs of wire that
rub
both drivers on the same axle. (equalizes the side forces if there are
two).
Offhand I can't think of a good way to otherwise do this since it would
require isolation from track voltage to switch the low level sound going
to
the amp IC. <snip>


Tom Knowles <ncstl@...>
 

Chris, thank you for your ideas...
you may be right about the club's power being pulse, or at least pulse
modulated. The sound is louder at club, too, so that may be part of the
answer. Actually the sound system is nothing more than a white noise
genrator and audio amplifier pair of IC's on a board with a few appropriate
resistors to set levels. Not a commercial unit, and there is no provision
for lights on it. The power is picked up through the rails via a diode
bridge and filter cap. Everything fits on a 24 pin IC socket and is in the
tender, including the 8 Ohm 1" dia. speaker. The ground is picked up from
the side of one of the loco's drivers with a wiper. The driver has four thin
crescent shapes of epoxy that interrupt the ground and just turn the circuit
on and off. The effect is stunning. Perhaps this is the wrong way to go
about it, I should leave the circuit on and switch the amplifier's input?
That would greatly complicate the switching and wireing arrangement at the
engine which at this point is only one wire and a little circuit board
screwed to the bottom of the frame. It has two hair-springs of wire that rub
both drivers on the same axle. (equalizes the side forces if there are two).
Offhand I can't think of a good way to otherwise do this since it would
require isolation from track voltage to switch the low level sound going to
the amp IC. I don't really want to disassemble the (finished) engines for
major frame surgery such as milling a slot for a four lobed cam, but it may
be the only way.

The lights are Headlight and cab lights, three of them each rated at 1.5
volts connected in parallel (microbulbs). There is currently no backup
light. They get their voltage from a separate set of diodes in series with
the motor in the traditional constant intensity lighting arrangement.
Nothing fancy here. Think about it some more and if the list is interested,
we will solve this problem somehow and get back to everyone as it
progresses.

Thanks for your help!
Tom


Thomas Beutel <fan2472@...>
 

Actually the sound system is nothing more than a white noise
genrator and audio amplifier pair of IC's on a board with a few appropriate
resistors to set levels. Not a commercial unit, and there is no provision
for lights on it. The power is picked up through the rails via a diode
bridge and filter cap. Everything fits on a 24 pin IC socket and is in the
tender, including the 8 Ohm 1" dia. speaker. The ground is picked up from
the side of one of the loco's drivers with a wiper. The driver has four thin
crescent shapes of epoxy that interrupt the ground and just turn the circuit
on and off. The effect is stunning. ...
Tom,

Is a diagram of the this circuit available? I'd love to build something like
this for my steam locos. It also might help us help you solve the problem.

Thanks!!!
Thomas Beutel
Redwoods and Pacific Railroad
San Francisco