A minor inconvenience....

[Jacktal]

I am progressing slowly on my layout,testing everything as I go along.I've discovered that when I run some of my locos(the older/cheaper ones especially),my layout creates horizontal streaks in TV screens upstairs.These are practically not noticeable with my newer locos but I like running my oldies also.My lady isn't upset by this as she says it's minor but I'd like to cure it anyway.Somebody knows of a simple solution?

[JCasey]

What I think your older motors are doing is creating an EMI field (electro mechanical interference) which is caused by an armature breaking an electrical field. I know a ceramic capacitor connected between the motor contacts and ground will filter the field, but what I don't remember is the value of the capacitor required. Perhaps one of the many electronic experts on the forum will help. Only half an answer I know, but the best I could do, sorry. John

[ndbprr]

Capacitors are neat things that can cause some serious shocks if mishandled because they store AC current but that is only at the real high capacitance values like used in TV sets. Rather than equip each engine you should be able to put a capacitor accross the output of your powerpack or power source. Then it will catch everything. I'd start at about 100,000 microfarad and double them until the problem goes away. Putting two in parallel won't halve the values like other electronic components and that size won't bite you if touch both ends. They should be very cheap at a place like Radio Shack.

[cacole]

Be aware that capacitors have a voltage rating, and it is recommended that you use one with triple the voltage rating of the applied voltage; i.e., for a 12 volt DC system, the cap should be rated at least 36 volts. Capacitors don't come in this voltage rating (35 is the nearest), so I would use a 50 volt cap in this case. Also, be sure you get a non-polarized capacitor or it could explode! Don't use a polarized electrolytic capacitor! You can tell this by the connections having + and - marks. You want an NPO (Non-Polarized) capacitor. Instead of investing in an electrolytic capacitor, which can get to be expensive and hard to find at the higher ratings, you could try smaller and cheaper mylar or ceramic disk capacitors with at least a 75 volt rating and see what happens. The principle behind a capacitor is that it passes AC voltage and blocks DC voltage, so you are looking for a blocking capacitor between the power pack's terminals to pass (ground out) the AC voltage spikes created by the old motors. In this usage, the voltage rating is more critical than the capacitance, and a NPO ceramic or mylar cap of .22 or higher should be OK.

[Anonymous]

I noticed this with a Lionel set and it helps if the tv is farther away, so maybe try moving it a litle farther away from the layout?????

[Anonymous]

I know almost nothing about electronics, or the terminology thereof in English, so this may sound funny:
In many old locomotives you could see what looked like (and in fact I think was) two simple copper wire coils on black "cores". Those cores were actually black "sticks" (no idea what those were made of), about an inch long in HO. Sometimes those "devices" would be inside a tube made of some insulation material. They were connected (soldered) one to each motor contact, directly. I was told that those coils actually help reduce the interference with radio and TV signals.

Those old locos also had a small ceramic disc capacitor connected directly to the motor contacts.

Hope this helps,
Oliver [:I]

[bcammack]

It's RFI created by the motor brushes on the commutator. Modern homeset slot cars imported from Europe generally have a small ceramic capacitor across the motor tabs as RFI abatement is required by law there.

Essentially, a capacitor blocks DC and passes AC, so a small uF ceramic cap shorts out the AC noise created by the motor brushes arcing on the commutator gaps as soon as it tries to get out of the motor. Figure a cap the size of a mechanical pencil eraser (I'm guessing .047pF would be good) and somewhere around 30 volt rating would be a safe choice (2x operating voltage+fudge factor).