TV interference

[mstechca]

This is ridiculous. I started to make the PCB for my uC programmer. The problem is that sometimes when I use my homemade drill, the TV has interference. As soon as I stop using it, the interference stops. The same applied when the food processor was in use.

My drill is just a basic motor circuit (motor connected to button, connected to power). Is there a possibility that maybe adding a capacitor or another component can prevent this interference from happening while the drill is on? if so, please tell me so that I can continue with my PCB's. I don't want to do them at 2:00am, and I go to bed by 12am as well. I also don't want the TV station to be changed.

 

[_3iMaJ]

You're going to have to explain what you mean by "interference." But I'll explain based on my first guess.

Assuming that it just makes your TV screen look fuzzy, I've had similar problems with appliances like a vacuum cleaner. DC motors create all kinds of noise on the line they are plugged into, and some how (I'm not sure exactly) this feeds back into the TV. Since it actually makes it to the monitor of the TV it has to be fairly high frequency noise (as I think channels start at like 20 MHZ).

So my first guess would be to put a coupling capacitor on the line. Which *should* filter out any of the high frequency nonsense, the problem is you're working with dangerous voltage and current levels so you must be very careful.

But what I would do first (if you have a working knowledge of some advanced techniques, I'll tell you what I'd do). I'd scope both the + terminal and the -terminal on the drill and do an FFT of the signal so I could find out what type of frequencies I was dealing with, and then I would design a simple low pass filter to get rid of all of the extraneous noise.

Good luck, and be careful.

Oh

P.S. You might try plugging your drill into another socket that isn't on the same circuit as the TV, that might even be a simplier fix.

 

[audioguru]

This is ridiculous. ...my homemade drill.

I spotted your problem right away. :lol:

Years ago my homemade fan brought me a visit by the RF cops. Its interference went pretty far. Now, my 40 year old electric drill also has worn-out brushes and is doing the same thing. Bright sparks and lots of ozone.

 

[samcheetah]

by looking at your posts it looks like the RF cops in Canada are really active. dont those guys have other things to do in life :lol:

 

[audioguru]

The Canadian RF cops went looking for me because my sparking fan interfered with thousands of TV's and they got many complaints.
I was young and didn't know any better. They were nice guys and we talked about radios and TV's and stuff.
I appologized to a neighbour who then bought me a new fan. :lol:

 

[Oznog]

A ceramic cap of the appropriate voltage rating is very commonly used to reduce RF noise in DC brush-type motors. I'm assuming this is your type. It should be right on the terminals of the motor.

In the USA we don't really have anything for enforcement at a home level. I think it's because we all have cable TV. Those who still have broadcast are nobody "influential".

 

[audioguru]

In the USA we don't really have anything for enforcement at a home level. I think it's because we all have cable TV. Those who still have broadcast are nobody "influential".

Sorry for the politics, but Canada is democratic. Everyone is "influential".
It was nice on my holiday in Cuba because there were no "influential" Americans there. :lol: