Looking for a source to purchase some exposed wire wound ceramic resistors. Similar to the type used in smoke units. Looking for some in the lower ohm range 20 - 24. The coated ones don't seem to get hot enough. Thanks
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Wire wound resistors are all enclosed, mainly for safety (fire), and to preserve the wire from being damaged and changing the resistance.
The ones used for smoke unit use have the coating ground off with a Dremel or similar tool to expose the winding.
See this post for more info.
Larry
I buy my resistors from Digikey, look for the 3 watt wire wound type. Most of them have a powder coating, I knock that off with the Dremel wire wheel.
A couple of threads on the topic.
https://ogrforum.com/t...45#29023674716534845
https://ogrforum.com/t...73#24659873191799573
Before and after.
Hi - Thanks for the replies - On one of the links found I could order some of the open wire wound. John I tried using a dremel to remove some of the coating - A little too heavy handed - wrecked 3 of them !!
hi John, is 18 ohms the pretty much standard fir most smoke unit resisters, which other ones are good to keep also!
Alan
Originally Posted by rrgeorge:
Hi - Thanks for the replies - On one of the links found I could order some of the open wire wound. John I tried using a dremel to remove some of the coating - A little too heavy handed - wrecked 3 of them !!
It does require a light touch, just rotate the resistor and hit it with the tips of the brush. Use the slow speed as well, less force.
Originally Posted by repair technician:
hi John, is 18 ohms the pretty much standard fir most smoke unit resisters, which other ones are good to keep also!
Alan
I'm not sure what smoke units have a "standard" 18 ohm resistor, none that I've used. MTH has 16 ohm resistors doubled up, Lionel uses 6, 8, 27, and 30. 18 ohms will certainly work for TMCC installations.
I have found the square ceramic resistors much easier to break open to extract the element. Just put it in vice and it breaks away cleanly without damaging the resistor.
The round ones with the thin coating take much more care to extract. I get these from Digikey and the brand is Stackpole.
Pete
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Originally Posted by TrainLarry:
Wire wound resistors are all enclosed, mainly for safety (fire), and to preserve the wire from being damaged and changing the resistance.
I believe wire wound resistors are coated to help conduct the heat off the resistance wire. Milwaukee Resistor custom winds wire wound resistors, but I do not know if they make anything small enough. If they have a core small enough, I am sure they would be happy to make resistors with out coating them.
Dear Norton
Can you please supply the Digikey part number for the square ceramic resistors.
rrgeorge,
Is this for a conventional engine or a command engine?
I like Norton's idea on cracking open the cover.
Here's the 27ohm for a conventional engine.
The 22ohm for a command engine.
http://www.digikey.com/product...CB5JB22R0-ND/1740805
If you use a lower resistance you can create a potential fire. Check youtube for caught fire clips.
So, on a conventional engine, here is Dale H's solution to get a slightly higher voltage to the resistor(more heat) safely.
Moonman those are not in stock
Pete, so you find the 5W resistors work fine? Looks like stackpole doesn't't carry the 16, 27 so you have to pick an off range. G
Ok guys. I ordered mine a few years ago and it appears the ones I have are no longer in stock. I have been getting 27 ohm resistors from Lionel. For 24 ohm resistors you can use Part # 24W-5-ND from Digikey. For 22 ohm resistors use Part # 40M8208 from Newark.
Pete
edit:
Now I see the 24 ohm 5W resistors are out of stock. Must be you trains guys are scooping them all up. Digikey shows this in stock but not sure how easy they will be to break open.
Thanks G and Norton.
Originally Posted by Moonman:
If you use a lower resistance you can create a potential fire. Check youtube for caught fire clips.
So, on a conventional engine, here is Dale H's solution to get a slightly higher voltage to the resistor(more heat) safely.
You're going to have to explain to me why dropping the voltage to the motor to increase the necessary voltage to run the train is any different than simply using a lower value resistor in the smoke unit in the first place. If you're getting the same volume of smoke you'd get with a lower value resistor, you're also dissipating the same amount of power in the smoke unit and generating the same amount of heat.
The issue of smoke units catching on fire is vastly overblown. Short of trying to use highly flammable products for smoke fluid, the risk of actually having a serious issue is very small. Even with the regulator failures I've witnessed (one personally), there was no flame, just a WHOLE LOT OF SMOKE. Think of a 6 ohm resistor with 18 volt AC track voltage on it, over 50 watts of power until it burns out the resistor! I've repaired a few of these, and no houses burned down as a result.
Quite frankly, you are far more likely to have a a high resistance electrical connection or short circuit start a fire than your smoke unit. There have been several posts in this forum where layouts caught on fire due to electrical connection issues.
Simple solution, don't leave your layout powered and/or running while unattended.
Originally Posted by gunrunnerjohn:
Originally Posted by Moonman:
If you use a lower resistance you can create a potential fire. Check youtube for caught fire clips.
So, on a conventional engine, here is Dale H's solution to get a slightly higher voltage to the resistor(more heat) safely.
You're going to have to explain to me why dropping the voltage to the motor to increase the necessary voltage to run the train is any different than simply using a lower value resistor in the smoke unit in the first place. If you're getting the same volume of smoke you'd get with a lower value resistor, you're also dissipating the same amount of power in the smoke unit and generating the same amount of heat.
The issue of smoke units catching on fire is vastly overblown. Short of trying to use highly flammable products for smoke fluid, the risk of actually having a serious issue is very small. Even with the regulator failures I've witnessed (one personally), there was no flame, just a WHOLE LOT OF SMOKE. Think of a 6 ohm resistor with 18 volt AC track voltage on it, over 50 watts of power until it burns out the resistor! I've repaired a few of these, and no houses burned down as a result.
Quite frankly, you are far more likely to have a a high resistance electrical connection or short circuit start a fire than your smoke unit. There have been several posts in this forum where layouts caught on fire due to electrical connection issues.
Simple solution, don't leave your layout powered and/or running while unattended.
email sent.
