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Discussion Starter · #1 ·
I have a car that I added a ITTC sound car to Years back and it has done well ......

but it has always had a little static in the speaker from sharing power with the decoder ......

so I desided to try and fix it .... the part I added is on the input power to the Ittc sound card ...

on the bench cliped to the power pack and DCC comand station it worked great no static at all and responded great I even lost the crack on startup....

once in the car it has some problems ..... it picked up a little static ( not to bad ) but now is way sentive to power pickup from the track and will cut in and out when rolling

it never did that before the extra electroincs on the input power .....

so do you think I should add more backup power caps or did I do something wrong ....






 

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Try connecting a little bitty capacitor across your 470uF cap. Like .01uF.

I just put it in a stock car with a 9v battery and 555 timer circuit to trigger it now and then. 9v battery lasts for many sessions, as in, I finally ran one down.
 

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On the output of your bridge rectifier, you show a diode and a resistor. What are they for? If you are trying to drop the voltage into your sound board, the diode is fine but the resistor will make the voltage unstable based on the sound volume. In addition to the small capacitor across the existing capacitor (how about making the 470 mfd one bigger) suggested previously, you might put about 1000 mfd directly across the bridge rectifier output. That will help carry you through a dirty spot on the track and stabilize the input voltage.
 

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Discussion Starter · #4 ·
though the battery idea would work I would also have to add a on off switch and remember to turn it on and off plus having to open it up to swap batterys is not great .......

I feel that one of the bennys of dcc is that you have power on the track all the time to run things like sound and dump cars and lights ..........


I think part of the problem is that the decoder has some sort of noise it puts back out on the power becouse the static only happens when I hook the decoder up ......

one thought I had was to hook the decoder up to power pickup from the other end of the car where the sound is hooked up so the track conection would help isolate them .......

the extra dioide is to help me drop 2 volts to stay under the max voltage input for the board ........

the resistor is there becouse I was told in the thread on car lights that when you run a cap that you had to limit the inflow current of the cap or the base station would trip becouse it would see the cap as a short for the moment it would charge ....

the resistor is also what got rid of the static when I bench tested the system .............

I am thinking I will try a bigger storage cap and see what happens but first I need to pull the system out of the car and see what kind of current it draws and how long it plays ......

I will keep you guys posted on how things go ......

also I am thinking about building a swing arm to trigger the cows if the car is handled rough like the old QSI system has anyone here done that ?
 

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Na, put a tiny cap across your storage cap to "short out" the high frequency from your DCC. You'd think the storage cap would do that, but it has a high "Inductance" a little cap won't.

I've been thinking about replacing the 555 circuit with such a gizmo. Would be cool.

I open the door to reach the battery and do any fiddeling.
 

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Posted By Trains West on 10/10/2008 8:29 AM

the extra dioide is to help me drop 2 volts to stay under the max voltage input for the board ........



A single diode only results in about a 0.7 volt drop. Scale Rails Magazine continually runs features on getting a nice smooth regulated dc voltage
from DCC systems.
 

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Discussion Starter · #7 ·
yes I know it drops .7 volts ...... you go thru two in the bridge and the one extra so you get .7 times three or 2.1 volts ..... if I just did the bridge I would get 1.4 volts
 

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Discussion Starter · #8 ·
I do understand that the smaller cap will respond faster and so will work better with the high freq ....

somehow I got more feedback from the decoder once I put it in the car .......

my big worry is the power to drive the sound card with out it cutting out .......

so I guess I will add a little cap and a big cap and see what I get .......


the swing arm is just a lead weight swinging from a tripod thru a hole in the board with a contact ring around the hole ......

it just cannot be that hard to make .......
 

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Scott - Is K-1 the full number on the Digitrax decoder you are using? I am having trouble finding it on the Digitrax or various vendor web sites. John
 

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Sometimes noise can be cross talk, 2 different electronic assemblies are too close to each other.

Try the capacitor across the 470uf cap. I prefer glass ceramics for high frequency noise.

Also, try placing a small ferrite core on the power leads to the sound board.
 

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Posted By Trains West on 10/11/2008 12:59 AM
yes I know it drops .7 volts ...... you go thru two in the bridge and the one extra so you get .7 times three or 2.1 volts ..... if I just did the bridge I would get 1.4 volts


I understand. I thought you were looking for a 2 volt drop beyond what the bridge provides.

Seems to me that the unit should be connected to that diode instead of after the resistor, and the resistor just moved, (horizontally) in series with just the cap. This still runs the current through the resistor so the cap does't appear as a short, but lets the unit get full power from the bridge without the dependancy on load inflicted by the resistor. May be worth a try.
 

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Thanks, Scott. Do you or anyone else know if the DS51K1 can be programmed and operated with an NCE system? I am trying to do the same thing you are with a calliope car and a RAM sound system.
 

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Discussion Starter · #14 ·
I use NCE switchkat all the time with the digitrax system ..... they all follow the NMRA rules so I see no problem

with the digitrax system I have to plug in to aqurie a loco but a switch can be thrown at any time so I use the car number as the switch number and at any point can pull it up and make it moo or baa ( the board I used has two sounds )
 

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The Digitrax DS51K1 instructions say "Using your (Digitrax) throttle select the address you want to program into the DS51K1 and press either c (closed) or t (thrown) to operate the turnout and program the address." NCE throttles do not have c or t keys, so I am wondering how this would be done with a NCE system.
 

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Discussion Starter · #16 ·
how do you throw switchs when you use the NCE switchkat ?

or use the switchkat board instead of the DS51K1
 

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Discussion Starter · #17 ·
CONTROLLING TURNOUTS AND
OTHER ACCESSORIES
ENTER THE ACCESSORY NUMBER TO BE OPERATED
CONTROL 02:00PM
ACC NUMBER: _
Press the SELECT ACCY key. Enter the address of the accessory to be operated.
Followed by pressing the ENTER key. Valid accessory addresses range from 1 to
2044.
TURN ACCESSORY ON OR OFF
ACC: 003 02:00PM
1=N(ON) 2=R(OFF)
Press 1 to turn accessory ON. (Switch machine set to Normal)
Press 2 to turn accessory OFF. (Switch machine set to Reverse)

The above is how to throw a turnout with a NCE controler ...

though the buttons are not the same as digitrax the language or packet info that goes out to the layout should be becouse that part is controled by the NMRA .......

so you would have to just hook up the program wire on the digitrax DS51K1 and make the number switch throw that you want it to be using your nec controler and then undo the program wire and you should be set .....

in other words the 1 and 2 on your deal becomes the t or c on the digitrax .......

I have even used lgb switch controlers on the digitrax controler before though they did not like the system startup .........
 

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Discussion Starter · #19 ·
after fussing with this car for way to long and trying every thing that I could from different values for the resister and caps to adding a toroid coil from a old LGB board I had I finely found the problem 's

first of the cutting in and out turned out to be my power pickup wheels and the 250 ohm resister with the resister in the circuit it was a little more fussy about power pickup so I cleaned all the black off the wheels and cleaned the axle and used a little conductive oil and droped the risister to 150 ohm and the cutting in and out is gone .........

but I still had the static ....

the static turned out to be the antenna effect of the track and power pickup deal I do on the wheels ...... so I move the power pickup to the other end of the car and that helped a lot but I still had a little so I then moved the box with the sound card from the floor to the underside of the roof and the static is gone .......

all this time I thought the static was coming thu the power but it was being broadcast by the power .......

one question I do have is what does anyone else use for conductive oil other the bachmann oil ?

 

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Scott,

Do you use conductive paste where the brass or copper tubes slide over the pins on the LGB/A-C axels?? Could you have used wires soldered instead of the tubes & got rid of the noise?? Mechanical joints can make electrical noise..

BulletBob
 
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