# Resistors to use in 70's steam engine on smoke unit



## old464 (Oct 12, 2011)

hey guys. saw the diagram on the sound of steam board. shows a 220 ohm resistor on the smoke unit to chuff the tender. 

Can I get these at radio shack? its a larger brown type. Im going to get ones for my crescent limited, my jersey central blue one, one of my 442 black engines. 

I tested the tenders and all are working good off a "good" engine. so its the resistor on the smoke unit. 

thanks 
Chris


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## gunrunnerjohn (Nov 10, 2010)

You should be able to get a 220 ohm resistor almost anywhere, including RS. Exactly how big is the resistor? "larger brown type" isn't must of a description, how about some measurements of diameter and length? What kind of marking, standard color codes?


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## servoguy (Jul 10, 2010)

220 ohm is a common size. RS may have it or they may have it in a smaller wattage. The larger resistors will dissipate more power. Small resistors are usually 1/10 or 1/8 watt. Larger ones go from 1/4 watt to 1/2 to 1 to 2 watts. If the resistor is too small, it will emit smoke.


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## T-Man (May 16, 2008)

You hit a sore spot. The resistor is 1/2 watt. SOmehow I found out to use the 220k resistor the 220 has more statis between the chuffs. This was my second video.







The smoke unit that has the acuator has 180 ohms,the difference between that and 220 is negligible. So all I can say is test it out. The diagram says 220 ohms also but I wonder if it is a mistake.


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## servoguy (Jul 10, 2010)

Remembering back 35 years, a friend of mine who is also an engineer and a train collector, said the SoS unit makes the chuff by taking the junction noise from a transistor and amplifying it. I think if you look at the circuit you will see a transistor with the base-emitter junction forward biased and nothing connected to the collector. I think it is this junction that makes the noise.


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## T-Man (May 16, 2008)

So far I have found no other source of info. The higher the resistance the quieter the background noise . The chuff noise is fine.


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## gunrunnerjohn (Nov 10, 2010)

I know it's certainly noise, never looked into the details on the one I fixed. I just replaced a cap and gave it back.


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## T-Man (May 16, 2008)

The resistor is in the smoke assy. The one that Jim gave is 180 ohms brown grey brown









,
Maybe it is higher than 1/2 watt, I used the 1/2 watt.


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## gunrunnerjohn (Nov 10, 2010)

What's a resistor there for? Could that be for the light bulb on the front? I can't imagine what a resistor of that value would be doing in the actual smoke circuit.


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## T-Man (May 16, 2008)

The resistor is the key to the works. It stops the continual noise/chuff. When bypased you get the chuff.










On my video the 220k quieted the noise until bypassed but the 220 didn't and noise leaked continously.


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## gunrunnerjohn (Nov 10, 2010)

I lost my place, I forgot we're talking about the SOS and not the actual smoke generation.


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## old464 (Oct 12, 2011)

yes, the resisitor is on the moke unit, but thats the wire that leads to rear of engine to connect to tender. 

good thing I asked. is not 220 as diagrams say. hmmm. im going to clip it out and take it with me also. But it has to be this resistor. because I try the tender I thought was bad with another engine and t chuffs strong. so tray these "non chuffing tenders on another engine first. it may not be the board at all! 

thanks for weighing in guys. 

Chris


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## old464 (Oct 12, 2011)

T-Man said:


> The resistor is in the smoke assy. The one that Jim gave is 180 ohms brown grey brown
> 
> 
> 
> ...


ok, that one I have looks identical. so 1/2 watt 180 ohm. cool. did you replace your old one with a new one and your tender chuffed now? the symptom mine is doing is steady chuuuuuusssssshhhhhhhh. no chuff. 

thanks chris


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## T-Man (May 16, 2008)

I left it as is. There is a background, that is continuous but it gets lost when the chuff starts. The 180 or 220 is a 10% variation off of 200 so it makes very little difference.Initially you get noise but you have to activate it discharge(jump the resistor) that what happenes to get a single chuff.


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## old464 (Oct 12, 2011)

im going toradio shack today to get a new resistor and solder it in and see what happens. 

so 180 ohm and 1/2 watt is what I need to ask for? I hope they know what I am talking about! 

thanks 
Chris


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## T-Man (May 16, 2008)

Resistors are funny and come in strange sizes. I haven't figured out why you need to change yours. I am not sure but they be 1 watt. In my test I did use a 1/2 watt resistor. They come in packages of 5 so find a number at 180 or higher. I do not think they stock 180 ohms. They have 220 ohms.

Remember this was a breakthrough in the 70's and it was for kids. The sound quality may be lacking but is was SOUND! Take it from somebody Who saw the invention of the color TV set. Cable was years away. but we had color and static was in color too!!!!!!

I am interested in this model since it was the first and collectors like better models. You are actually one of the first to come along and show some interest about owning one.

My actuator works so I should have it running with the tender in the near future.


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## gunrunnerjohn (Nov 10, 2010)

If they don't know what you're talking about, try a different sales person!


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## servoguy (Jul 10, 2010)

Radio Shack's web site shows that they have 220 ohm, 1/2 watt resistors in the stores.


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## old464 (Oct 12, 2011)

http://www.radioshack.com/search/in...istors&origkw=220+ohm+1/2+watt+resistors&sr=1

there are 2 types here. which one? 

i am redoing these engines i have and selling some so i want them to work right and its in the engines when i test the tenders they are ok. 

im keeping the crescent so its got to work better also.

1/2 watt 180 or 220? what worked best for you? 

thank you for your help
chris


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## gunrunnerjohn (Nov 10, 2010)

The 1/2W carbon film is fine.


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## old464 (Oct 12, 2011)

so I got the 1/2 watt 220 ohm. worked like a charm and now the old jersey central is chugging again. so now its on Ebay! I have 3 others that need the resistors. 

Chris


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