Polarity flipping circuit ...

[DeepCut]

Please excuse what is most probably my ignorance but i don't think the 555 or h-bridge solutions are what i need.

I'm trying to do a solid-state version of Jo Newman's 'special commutator'.

I've got a PWM that will pulse the coil at 24 Hz.

I want the polarity of the output of the PWM to reverse at 2 Hz.

So, every 12 pulses the polarity should reverse.

Any help greatly appreciated


Gary.

[DreamThinkBuild]

Hi DeepCut,

Is the attached picture the kind of signal you are trying to generate?

This could be saved as a 32 bit floating point .wav file. If you have a small MP3 player in loop mode or computer audio you could feed the signal out to a power mosfet to drive your circuit.

I attached the code so you can change the settings.

I coded it in Octave which is a open source Matlab like clone.
http://www.gnu.org/software/octave/

For a circuit what I see is a 1Hz square wave signal with a 24Hz square wave. Feed the 1Hz wave into the + of a OpAmp and the 24Hz into the negative. When the 1Hz wave is positive the 24hz wave will be positive. When the 1Hz wave goes negative the 24Hz wave will be negative. So you should get a 12Hz +/- waveform out.

[DeepCut]

Thanks DTB

I've always loved your name now i love you too ;+}

What a novel approach !

Thanks again,

Gary.

[DeepCut]

Although now i think about it, it would still be a positive signal coming out of the MP3 player

OCTAVE looks really, really interesting, a bit like BASIC but specialised.


Gary.

[DreamThinkBuild]

Although now i think about it, it would still be a positive signal coming out of the MP3 player.

Still positive? How negative do you need them?  I have a MP3 player with multiple test signals(sine, square, etc) 30hz, 50hz, 60hz, 120hz files and they look fine on the scope.

Octave is a really nice language for math processing. I've programmed in other languages but so far Octave is the best when working with signals.