Re: TOMIX 6421 DC TRACK CLEANING CAR
There should already be a full wave rectifier between the track pick up and the motor so the track cleaning motor will always run in the same direction with either polarity on DC to the track. So add a single diode between one side of the track pick up and the input of the rectifier to half wave rectify DCC. This will cut the average voltage available to the motor to roughly 6 volts.
DonV
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Re: TOMIX 6421 DC TRACK CLEANING CAR
The Tomix car already has the full wave rectifier and so will run at a blazing speed when on DCC powered track. The N scale voltage should be more like six Volts. So a number of series diodes connected to the motor would suffice to drop the voltage sufficiently and pretty easily. I don¡¯t know why I did not think of this. The current demand is just under one Ampere so I would use 1N400X diodes where the x is any number you can get easily. I put in a decoder in my original one but current production requires a pretty beefy decoder IMHO.
Ken Harstine
413-250-8298
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Re: TOMIX 6421 DC TRACK CLEANING CAR
DCC is a AC. You could rectify it with a full wave rectifier chip. And then experiment with different resistors in series on the motor side, to get the speed you are looking for. I assume what you are trying to do is run the car at a constant speed of your choosing on a DCC only layout. ?If you want to control the speed and direction, then you need a separate power source. That¡¯s what I do so I can run both DCC engines and alternatively ones I haven¡¯t converted yet. Use a DPDT center off switch to switch between power sources.
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On Sep 20, 2023, at 5:45 PM, Allan AE2V <bigboy@...> wrote:
?Putting one diode in series with the motor will probably make it run at half speed.? Trying this out on your bench before opening your track cleaning car.
Putting a resistor across the motor will definitely not help.
Allan
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Re: TOMIX 6421 DC TRACK CLEANING CAR
Putting one diode in series with the motor will probably make it run at half speed.? Trying this out on your bench before opening your track cleaning car.
Putting a resistor across the motor will definitely not help.
Allan
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Re: TOMIX 6421 DC TRACK CLEANING CAR
Again, not that I'm a an expert, but I always thought hat the DCC voltage to the tracks was constant and that if you modify the DCC Rail Voltage, that would affect how ALL the DCC locomotives would function.
Doug Wagner
Bakersfield CA?
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In a message dated 9/20/2023 17:30:49 Pacific Daylight Time, mrmrsv5049@... writes:
?
I am looking for a way to modify the DCC RAIL VOLTAGE to DC for the DC motor. NO DECODERS
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Re: TOMIX 6421 DC TRACK CLEANING CAR
I am looking for a way to modify the DCC RAIL VOLTAGE to DC for the DC motor. NO DECODERS
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Re: TOMIX 6421 DC TRACK CLEANING CAR
Not that I'm an expert, but isn't any non-DCC locomotive on a DCC layout operated with the address of 00?
Doug Wagner
Bakersfield CA?
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In a message dated 9/20/2023 15:09:40 Pacific Daylight Time, vandoornw@... writes:
?
Sorry. Never mind. Read it too diagonally. Ignore!
On Wed, 20 Sept 2023, 23:07 Wouter van Doorn, < vandoornw@...> wrote:
Lawrence,
?
What's wrong with changing the speeds via the decoder CVs?
?
Wouter
I want to convert this N scale DC ONLY car to run on DCC. The DCC voltage from my Power Cab is 12.4v. This makes the motor run at high speed as if it were 12VDC.
I don't want to tear out the electronics and wire in a DCC decoder like numerous YouTube videos do.
Can I add a diode (half wave) and maybe a resistor across motor input voltage to reduce the motor speed?
If so, what would the DC voltage to the motor be?
Any approach is welcomed.
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Re: TOMIX 6421 DC TRACK CLEANING CAR
Sorry. Never mind. Read it too diagonally. Ignore!
On Wed, 20 Sept 2023, 23:07 Wouter van Doorn, < vandoornw@...> wrote: Lawrence,
What's wrong with changing the speeds via the decoder CVs?
Wouter
I want to convert this N scale DC ONLY car to run on DCC. The DCC voltage from my Power Cab is 12.4v. This makes the motor run at high speed as if it were 12VDC.
I don't want to tear out the electronics and wire in a DCC decoder like numerous YouTube videos do.
Can I add a diode (half wave) and maybe a resistor across motor input voltage to reduce the motor speed?
If so, what would the DC voltage to the motor be?
Any approach is welcomed.
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Re: TOMIX 6421 DC TRACK CLEANING CAR
Lawrence,
What's wrong with changing the speeds via the decoder CVs?
Wouter
I want to convert this N scale DC ONLY car to run on DCC. The DCC voltage from my Power Cab is 12.4v. This makes the motor run at high speed as if it were 12VDC.
I don't want to tear out the electronics and wire in a DCC decoder like numerous YouTube videos do.
Can I add a diode (half wave) and maybe a resistor across motor input voltage to reduce the motor speed?
If so, what would the DC voltage to the motor be?
Any approach is welcomed.
|
TOMIX 6421 DC TRACK CLEANING CAR
I want to convert this N scale DC ONLY car to run on DCC. The DCC voltage from my Power Cab is 12.4v. This makes the motor run at high speed as if it were 12VDC.
I don't want to tear out the electronics and wire in a DCC decoder like numerous YouTube videos do.
Can I add a diode (half wave) and maybe a resistor across motor input voltage to reduce the motor speed?
If so, what would the DC voltage to the motor be?
Any approach is welcomed.
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Hi thanks for the information.when built this pot I did burn up a few leds then added a 470 resistor to it which solved the problem .This pot going to be used for testing leds for brightness.what I did find out was the100k worked fine for me . the problem I was having is using resistors from1k-220 ohms which were to bright and bought resistors trying to find out which way to go and went online found resistance calculators and i couldn¡¯t figure it¡¯s light level.nick showed some of brightness levels he was working on which I trying to achieve .then someone suggested a pot .
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The politically incorrect mnemonic for resister values that I learned in school is:? "Bad Boys Rape Our Young Girls But Violet Gives Willingly" where Bad = Black, Boys = Brown, Rape = Red, Our = Orange, Young = Yellow, Girls = Green, But = Blue, Violet = Violet, Gives = Grey, and Willingly = White.? You use is as follows:? Black - 0, Brown - 1, Red - 2, Orange - 3, Yellow - 4, Green - 6, Blue - 6, Violet - 7, Grey - 8 and White - 9.? When reading a resister first 2 bands are numbers, 3rd band is number of zeros and 4th band is tolerance: Gold is 5% and Silver is 10%.? So if a resister is banded Brown-Black-Red-Silver it is 1,000 ohms 5% tolerance.? In the resister you used the bands are decoded 1, 0, 4 zeroes, and 5% or 100,000 ohms.
I installed hundreds of LEDs in locomotives over the years and have always used 1,000 ohm 1/4 watt resistors and have never had a failure.? If it too bright for your liking you use the decoder CV settings to lower the brightness.? If you use too high a resistance you are stuck with a dim headlight as you can't make it any brighter but you can always make it dimmer.
Good Luck, John Moonan
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Guys (and I hope ladies),
? ? In the old days we used to use Resistor Substitution Boxes to figure out the necessary resistor. I bult my first in my first rear of high school and have built a few since as they wear out. They can be purchased for about $25, and they are available as kits. I double up when i build them and use both 1/4- and 1-amp resistors as 1/4-amp resistors carry very little current. The cheap way out is to use a breadboard and alligator clips.
????
Have fun JD
On Tuesday, September 19, 2023 at 10:41:17 AM EDT, Rick Jones <r.t.jones@...> wrote:
? ? We ran into these issues on some of the latest control panels I
built at the club. We switched to some high efficiency ultrabright LEDs
for certain colors. With the 2.2K resistors we'd been using for standard
LEDs for a while, they were much too bright. I had to use the pot trick
I previously mentioned here to find a resistor value that made them look
about the same brightness as normal LEDs on the panel. IIRC I wound up
adding over 200 Kohms to the existing resistor to reduce the brightness
sufficiently on those ultrabrights.
? ? ? ? ? ? ? ? ? Rick Jones
Work harder. Millions on welfare depend on you.
On 9/19/2023 2:55 AM, PaulXpress wrote: > The problem with adjusting light intensity is that the light perception > curve is not linear. > > <> > > It is still simpler to refer to the LED technical sheet to have at least > an idea of its brightness, but you still need to have the LED reference. > > Between the two LED references, the intensity of the stronger one > (OSXXXX3131A-1MA) must be reduced to 10% to have the same light > perception as the weaker one at 100% (OSXXXX3164A-1MA). > > This is why I only buy LEDs for which I have the reference. > > /g/w4dccqa/album?id=289626 > < /g/w4dccqa/album?id=289626>
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We ran into these issues on some of the latest control panels I built at the club. We switched to some high efficiency ultrabright LEDs for certain colors. With the 2.2K resistors we'd been using for standard LEDs for a while, they were much too bright. I had to use the pot trick I previously mentioned here to find a resistor value that made them look about the same brightness as normal LEDs on the panel. IIRC I wound up adding over 200 Kohms to the existing resistor to reduce the brightness sufficiently on those ultrabrights.
Rick Jones
Work harder. Millions on welfare depend on you.
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On 9/19/2023 2:55 AM, PaulXpress wrote: The problem with adjusting light intensity is that the light perception curve is not linear.
<>
It is still simpler to refer to the LED technical sheet to have at least an idea of its brightness, but you still need to have the LED reference.
Between the two LED references, the intensity of the stronger one (OSXXXX3131A-1MA) must be reduced to 10% to have the same light perception as the weaker one at 100% (OSXXXX3164A-1MA).
This is why I only buy LEDs for which I have the reference.
/g/w4dccqa/album?id=289626 </g/w4dccqa/album?id=289626>
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Decoder outputs usually are rated for 100 mA (1/10 Amp), so aren't likely to be hurt by smaller resistances. At 14V, any resistor of 140 Ohms or more will limit current to 100 mA or less. Check the function current rating of the decoder you are using to confirm the 100 mA rating, or learn its actual rating and adjust the minimum resistor size accordingly (double the resistance halves the current, and so on.)
The eye is a lousy sensor of light intensity. It's not able to distinguish two levels that are similar. So, you need to change resistances quite a bit to change observed LED brightness much. Your various resistances were all low, making the LEDs very bright, and changes hard to distinguish.
100,000 is the same as 100k. The k is scientific notation for 1,000 times.
If you use a pot to find the resistance you need for the brightness you want, then I strongly recommend putting a 1.0k resistor (1,000 Ohm) in series with the pot (in the line from the power source to the pot) to limit the minimum resistance and maximum current to safe values. If the pot is used alone, then turning it to one end will present a near short circuit, allowing excessive current flow that probably will destroy the LED and the decoder function output transistor, if using with a decoder. Measure the resistance from the power source end across the resistor and pot to the load (LED) end for the fixed resistance you need.
At or above 1.0k Ohms, on 14V, the power dissipated in the resistor as heat is 196 mW (196 milliWatts/0.196 Watts.) A 1/4 Watt resistor will get pretty hot at 196 mW, being nearly 80% of its power rating.?
Above 2.5k Ohms, even a 1/8 Watt resistor is fine, and smaller than the 1/4W. The body size depends on the amount of heat the resistor has to dissipate into the surrounding still air, and how hot the materials it's constructed of can be without damage. Some power resistors can be operated at much higher temperatures without damage, but are hazards to human flesh and other typical electronic components.
If brightness is OK at 100k Ohms, then you are operating those LEDs at about 12/100th of one milliAmp, which is tiny. The resistor won't even get noticeably warm, nor will the Tortoise power supply load be significantly increased.
-- Don Weigt Connecticut
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Dennis,
Especially if you try the pot approach, be sure to put at least a 470 ohm resistor in series with it while you run your test.? This will prevent blowing the LED should you turn your pot all the way to zero ohms by accident.
Yes, when done, you should add the 470 to whatever you determine with your pot.? But especially if you end up with 10k or so, the 470 won't make a visible difference.? Also, you cannot buy a 10.47k resistor.
I see a few people recommended trying a 4k ohm resistor.? 4k is not a standard value.? You will not find a 4.k for sale at the typical hobbyist supplier. 3.9k and 4.3k are.? If you try either of these, you will not likely notice a difference if you had a 4k.? If you really want 4k, try 4 1k resistors in series.
Allan
Wiring for DCC.
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The problem with adjusting light intensity is that the light perception curve is not linear.
It is still simpler to refer to the LED technical sheet to have at least an idea of its brightness, but you still need to have the LED reference.
Between the two LED references, the intensity of the stronger one (OSXXXX3131A-1MA) must be reduced to 10% to have the same light perception as the weaker one at 100% (OSXXXX3164A-1MA).
This is why I only buy LEDs for which I have the reference.
/g/w4dccqa/album?id=289626
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Hi guys going to try what rick said.I have a pot that will work,it may help ? This my first time doing this ?it¡¯s a new learning curve for me I have ordered ?100 k ?1/4 watt resistors .
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Dennis,
I have never heard what you mention about too much draw. I use 1/4 watt and have not had any issues.?
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From my understanding from 1k or 1000ohms ?resistors and under is drawing to ?much current ,which is could be problematic with decoder boards ?. I have several decoders that are using ?470 - 620 ?ohms ?. I was told these were average for esu ,soundtraxx
older boards so I will change them to 1-3k ohms if this is correct. ?What I¡¯am doing now is attaching leds to my tortoises so I don¡¯t have to see what switch is thrown on the layout ?and look at the panel instead so what I have is a 100.000 ohm resistor which
is a 10 k I think ?which works great. ?so I was going in the wrong direction ?with resistance ?. Thanks learned something new. Pease correct me if wrong.
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From my understanding from 1k or 1000ohms ?resistors and under is drawing to ?much current ,which is could be problematic with decoder boards ?. I have several decoders that are using ?470 - 620 ?ohms ?. I was told these were average for esu ,soundtraxx older boards so I will change them to 1-3k ohms if this is correct. ?What I¡¯am doing now is attaching leds to my tortoises so I don¡¯t have to see what switch is thrown on the layout ?and look at the panel instead so what I have is a 100.000 ohm resistor which is a 10 k I think ?which works great. ?so I was going in the wrong direction ?with resistance ?. Thanks learned something new. Pease correct me if wrong.
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Ken Harstine
Doug Wagner
Rick Jones