UPDATE - How do I eliminate interference on an AM radio

[fiatfan]

I left the orgininal question below. After spending time twisting all of my feeders and separating the ac and dc lines (per step one of Fergie's reply - see below) I stated running things while my wife listened upstairs. Turns out it was the halogen lights. I will try some type of surge supressor to see if that cures it. Thanks again to all for your help.

Tom

Original message:
My wife goes to bed much earlier than I do. When she does, she frequently listens to the radio (AM). I did suggest that she listen to FM but all that got me was a dirty look! I can't imagine why.

There is some interference from the power packs coming through the wires. She says it's not too bad but if she mentioned it, it must be annoying her.

I am using a homemade transistor throttle and using an old American Flyer transformer for power.

Is there anything I can do to reduce or elimate the interference?

Tom

[lonewoof]

You might try getting some RF choke coils from Radio Shack and put them in series with the power feed from your throttle; it might work better if you located them at the track end rather than the throttle end. Chances are the noise is coming from wheels arcing (cleaning the track might help) or motor brushes (sometimes a small capacitor (.001pF or so) connected across the motor leads will help). It's a real inexact science and could involve a lot of trial-and-error.

[Anonymous]

I listen to AM radio while running my equipment and fine most of the small amount of static I get is from the tube lights. What does she listen to on AM music of your life?

[cacole]

Conduct a test. Listen to the radio with the fluorescent lights on but the train not running; then with the train running. If the interference is definitely from the train, get some hash filters as lonewoof suggested, and put one in each power lead where the wires connect to the track. A capacitor could also be placed between these two filters chokes instead of having to modify the locomotive. Since you're using a transistor throttle, I assume you're running DC motored locomotives and not American Flyer AC. A capacitor blocks DC voltage but passes AC, so the capacitor should filter out most of the RF interference by passing it to the transformer ground. If you still have interference, try plugging the AF transformer into a surge suppressor. They also contain capacitors, and will add further RF filtering.

[fiatfan]

Thanks for the help everyone.

Yes, I am running dc rather than dcc (forgot to mention that, sorry). There are no flourescent lights running. It is definitely coming from the transformer.

Some questions -

Can I put the rf chokes in line right after the output from the throttle rather than putting a pair at each place where the feeders attach to the track?
Does the capacitor go before or after the choke coils?

Tom

[bcammack]

It could also be noise from the DC motors in the locomotives as well. I seem to recall that the Scalextric slot cars have a ceramic disc capacitor across the motor tabs to help kill the RFI (Radio Frequency Interference) the brushes make arcing on the commutators. Something about European RFI regulations as I recall.

[Fergmiester]

You might try these options or at least experiment.

1) put turns in your engine's +/- wires as the wires transmit rf waves. wrapping/twirling the wires together can minimze and even cancel errant rf interference you may want to try this on your DC power supply wires.

2) Take a washer and after wrapping/twirling your DC power wires feed them through the washer and wrap the wires around the washer several times (poor man's choke) before sending it to the track. This is not the scientific approach but can be done cheap and easy.

Regards
Fergie

[fiatfan]

Thanks, everyone, for all the tips.

We had our thanksgiving today and have had a house full of people since about 10 this morning. I will check out the results and post later in the week. I have been off for about a week and a half and have to return to work tomorrow so by tomorrow night, I know it will be one of those eveinings when even the mouse is heavy.

Thanks again, everyone.

Tom

[cacole]

The filter chokes would best be placed as near the layout as possible, with the capacitor wired between the two chokes; i.e., have a choke in each wire and the capacitor connecting the two chokes together, right before your first connection to the track. If you have multiple power feeds, put the chokes wherever the output from the throttle is first connected to the layout. Instead of soldering these things in permanently, I would use jumper wires with alligator clips on the end to make a temporary hookup and see if this is really going to help. If it doesn't, you can return the components and get your money back.

[brokemoto]

Funny, I used to use this to torture my sisters when, as a pre-teen or in High School, I lost the battle of what we watched on the boob tube. My parents almost always let my sisters watch what they wanted, so down I would go to the basement to run my trains some more (I usually had already run them earlier in the day). It would create so much static that the sisters could not enjoy their programme. They, of course, would cry to my parents, but my father steadfastly refused to tell me not to run my trains (he got me interested in this hobby). SO, eventually, I would get to watch my programme. Whenever it looked like there was going to be a dispute, I would say 'fine. I'll go operate my trains'. I would get my way, then.

Of course, if my father wanted to watch something, he would not permit me to turn on my trains.

[railman]

QUOTE: Originally posted by brokemoto

Funny, I used to use this to torture my sisters when, as a pre-teen or in High School, I lost the battle of what we watched on the boob tube. My parents almost always let my sisters watch what they wanted, so down I would go to the basement to run my trains some more (I usually had already run them earlier in the day). It would create so much static that the sisters could not enjoy their programme. They, of course, would cry to my parents, but my father steadfastly refused to tell me not to run my trains (he got me interested in this hobby). SO, eventually, I would get to watch my programme. Whenever it looked like there was going to be a dispute, I would say 'fine. I'll go operate my trains'. I would get my way, then.

Of course, if my father wanted to watch something, he would not permit me to turn on my trains.

That's a great story!

[cacole]

Okay, don't keep us in suspense any longer -- WHAT halogen lights? There was no mention of halogen lights in your original post. Do you have your train room lit with halogen lights? Some people assumed you had fluorescent lighting, but you said you don't.

[Fergmiester]

Of course when I originally posted here I didn't have a problem, not until my eldest son thought his game cube was bust. Turns out some of my "cheaper" engines are pumping out all kinds of RF interference. As has been already suggested by Lonewolf, bcammack and cacole and from what I can remeber from my RC days this can be easily handled by putting a small ceramic disc capacitor across the +/- terminals of your motors.This does wonders. As to the actual capacitance value, from what I can remember it was a hit and miss thing and was dependent on the actual motor.

Please remember before you start to tinker you may want to verify this as I will not take responsibility if you smoke your motor!

As for your problem with the Halagen lights it sounds like one of your ballasts/transformers may be causing the grief. Is there a way you can isolate each light to find the culprit?

Regards
Fergie

Remember only real steamers and diesels are suppose to smoke!

[fiatfan]

My sincerest apologies, cacole. I completely overlooked them when describing the problem.

I have two strings of 10 watt halogen lights nailed to the ceiling over the layout for additional lighting. They are wired in to the light switch along with the incandescent bulb.

As indicated, I will try a surge supressor to see if that will filter it out.

Again, I apoligize for the confusion.

Tom