Mains Bandstop FIlter

Hi All,

Im trying to find/ piece together a 250VAC bandstop filter circuit.

I'm trying to filter out a 1050Hz signal being put through the grid by our energy supplier. The filter will be used specifically on a ceiling fan (one filter for each).

The ceiling fans are rated at 250VAC and draws 250, 167 & 125 mA (AC) at each of its three speeds.

Any idea where I can start? I need to be able to use well stocked electronic components and have the circuit come in under $30 (Australian).

Cheers, Daniel

Reply to
daniel_vaughan
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** Looong time since I saw anyone ask for this one.

What I have seen published is parallel tuned circuit set to the tone's frequency - like a 10 mH iron cored inductor with a 2.2 uF, 250 volt AC cap in parallel. The " notch filter " is simply wired in series with the fan motor.

This will produce a fairly high impedance at around 1050 Hz - but may not provide enough attenuation on its own to do the job since the fan motor's impedance will be high at that frequency too.

You could add a series RC ( ie Zobel network with say 2.2 uF and 100 ohms

10W ) or even a similar series tuned circuit ACROSS the motor to increase attenuation if needed.

Jaycar sell a 9mH ferrite cored inductor ( cat: LF1336 ) for not too many dollars intended for speaker x-overs so should easily handle the low current you need.

YOU will have to experiment to get the filter onto the exact frequency.

You do have basic test gear for this - don't you ?

...... Phil

Reply to
Phil Allison

What does "filter out" mean? Detect the presence of? Or remove?

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Reply to
Jim Thompson

I'd use a pi network, or maybe even something like a common-mode choke with a couple of caps so it's parallel-resonant at 1050 Hz.

Good Luck! Rich

Reply to
Rich Grise

That's the stall current?

L-C notch filter

that'a a tough one, a suitable inductor rated to pass 250ma is likely to blow much of that budget

Bye. Jasen

Reply to
jasen

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