Large Scale Central

Slowing Down a Switcher

Electronics Power and Sound
#1

I have an electric Aristo Craft 0-4-0 with sound and puffing smoke that I use on my switching problem. It is track powered using an Aristo Craft TE with the Aristo 10 amp power supply designed to plug into the TE. I run the engine on full wave DC, not the PWC option. The engine is very smooth and runs at a comfortable switching speed at a voltage less than the sound and smoke need to begin to work. According to the Aristo Craft instructions, the sound and smoke need 6 volts to operate and at 6 volts on the track the engine runs to fast. Even on PWC the engine runs to fast before the smoke unit starts to work. Is it possible to put a resistor in one of the motor leads that will allow the sound and smoke to come on before the engine starts to move? I know resistors can get hot. I am worried that a resistor large enough to perform this way would get so hot that it would damage the plastic engine. I also need to know what size resistor I would need to obtain. I haven’t opened the engine up yet to even see if I have room to do this. Perhaps the heat problem could be solved by hanging the resistor in the the open air in the cab, not close to anything that would melt. The engine is only used as a switcher, so top end speed is unimportant. If y’all feel this isn’t practical, just say so. Any help and opinions will be greatly appreciated.

Oldpartsmaker

#2

Check out this site. May have some info that will help you:
http://www.jcstudiosinc.com/BlogShowThread?id=488&categoryId=559

#3

Phil,
Thanks for the direction to the diode post. Looks like just what I’m trying to do. I’ll make up the diode string as soon as I can get to Radio Shack. I’ll post the results. Thanks again.

#4

John, a simple diode circuit allowing voltage reduction plus directional lighting and constant cab lighting. considering that each diode reduces voltage by 0.5 - 0.7 volts, use required number of diodes in the vertical diode stack to achieve final voltage to the motor. ‘A’ and ‘B’ are directional lights and ‘C’ is continuous cab lighting. From memory I copied this diagram from the the MAD forum site some years ago.

(http://freightsheds.largescalecentral.com/users/tim_brien/_forumfiles/aElectcircMotor.jpg)

#5

Dear All,

To simplify the math in the above diagram, assume max of 0.7 V per diode.

Max voltage Bulb A or Bulb B = (vertical stack +1) x 0.7 V, in this case (5+1) x 0.7V = 4.2 Volts.

Max voltage Bulb C = (vertical stack + 2) x 0.7 V, in this case (5+2) x 0.7V = 4.9 Volts.

In their dimmed mode (loco moving in opposite direction), max voltage Bulb A or B = 0.7 Volts.

Hope this helps.

Sincerely,

Joe Satnik

Edit: Added “in the above diagram”

#6

Last April I asked the question in the first post. The answers I received seemed to be the perfect solution. I finally built the diode string suggested in the answers using 5 6amp diodes on each side of the diode string. Got it all put back together and it runs fine, but it still doesn’t slow the engine down enough to make the chug work at a slow switching speed. The voltage drop thru the 5 diodes is supposed to be a shade over 2.1 volts. So am I going to have to put 12 or more of these diodes in each side of the string to get an appreciable voltage drop? The string is in one of the motor leads. The chug and lights still receive full power. Help Please!

#7

Yes, the diode string solution will work, but what a mess ! It takes a lot of soldering, space, and just wastes your battery power. Try a “Simple Critter Control” to finely adjust your motor speed to whatever you want without wasting battery power, and no soldering! http://1stclass.mylargescale.com/DelTapparo/gscalegraphics_1_018.htm

#8
Del Tapparo said:
Yes, the diode string solution will work, but what a mess ! It takes a lot of soldering, space, and just wastes your battery power. Try a "Simple Critter Control" to finely adjust your motor speed to whatever you want without wasting battery power, and no soldering! http://1stclass.mylargescale.com/DelTapparo/gscalegraphics_1_018.htm
Yeah, but...yeah, but...yeah, but... where's the challenge? What's the fun in that???? :P

Was gonna suggest that meself, but ye beat me to it!

#9

OK. So yesterday I added 15 diodes to each side of the diode string. 20 diodes now in each side, total of 40 used. Engine still responds as if I had done nothing to it. Starts way before sound and smoke comes on. Is running way to fast to switch with when sound does come on. What the heck do I try now.

Del, you suggested your gadget, but I would need two of them wired in like the diodes to reduce the motor speed to where the smoke and sound would start before the engine starts to move. Mounting them might be a problem. Don’t necessarily object to buying two of them, but your ad says battery power. I am running track power.

Somebody explain why the diodes don’t work?

#10

Sooooooooooo … did you actually measure the voltage at the motor?

#11

Have you considered a sea anchor??? :stuck_out_tongue:

#12

Use a diode bridge and then you only need diodes in one direction between the + and - of the bridge, and wire the ~ sides in series with a motor.

Much easier than dual diodes and less parts!!!

#13

The original circuit from Tim IS a diode bridge (the “outer” 4 diodes)… just add more diodes in the “long string”… packing a bunch of diodes in a small space easily is no problem, here’s 10 in a small, easy to solder space:

(http://www.elmassian.com/images/stories/electronics/misc/diode_stack1.JPG)

Greg

#14

Quote: “OK. So yesterday I added 15 diodes to each side of the diode string. 20 diodes now in each side, total of 40 used.”

John,
if you used a total of forty diodes at 0.7 volts drop per diode and 20 per side, then that is a voltage drop of 14 volts approximately. I would measure the actual input to the motor after the diode pack to verify an actual volt reduction has occurred. The Aristo TE only outputs 18 volts so with a 14 volt diode reduction this only leaves 4 volts to the motor. If using the stock Aristo onboard sound in the tender, then your actual ‘problem’ is that you are using linear power for the loco. If you used PWC then the sound and smoke will start almost immediately power is applied.